Move test crates into a "testing" folder and add a ui (trybuild) test and ui-test helpers (#567)

* move test crates into a testing folder and add a ui test and helpers

* undo wee mixup with another PR

* cargo fmt

* clippy

* tidy ui-tests a little

* test different DispatchError types

* refactor dispatch error stuff

* name ui tests

* duff => useless

* align versions and cargo fmt

testing/integration-tests/Cargo.toml

@@ -0,0 +1,33 @@
+[package]
+name = "integration-tests"
+version = "0.21.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+
+license = "GPL-3.0"
+readme = "../README.md"
+repository = "https://github.com/paritytech/subxt"
+documentation = "https://docs.rs/subxt"
+homepage = "https://www.parity.io/"
+description = "Subxt integration tests that rely on the Substrate binary"
+
+[features]
+default = ["subxt/integration-tests"]
+
+[dev-dependencies]
+assert_matches = "1.5.0"
+codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false, features = ["derive", "full", "bit-vec"] }
+frame-metadata = "15.0.0"
+futures = "0.3.13"
+hex = "0.4.3"
+scale-info = { version = "2.0.0", features = ["bit-vec"] }
+sp-core = { version = "6.0.0", default-features = false  }
+sp-keyring = "6.0.0"
+sp-runtime = "6.0.0"
+subxt = { version = "0.21.0", path = "../../subxt" }
+test-runtime = { path = "../test-runtime" }
+tokio = { version = "1.8", features = ["macros", "time"] }
+tracing = "0.1.34"
+tracing-subscriber = "0.3.11"
+wabt = "0.10.0"
+which = "4.0.2"

testing/integration-tests/src/client/mod.rs

@@ -0,0 +1,133 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+    test_node_process,
+    test_node_process_with,
+    utils::node_runtime::system,
+};
+
+use sp_core::storage::{
+    well_known_keys,
+    StorageKey,
+};
+use sp_keyring::AccountKeyring;
+
+#[tokio::test]
+async fn insert_key() {
+    let test_node_process = test_node_process_with(AccountKeyring::Bob).await;
+    let client = test_node_process.client();
+    let public = AccountKeyring::Alice.public().as_array_ref().to_vec();
+    client
+        .rpc()
+        .insert_key(
+            "aura".to_string(),
+            "//Alice".to_string(),
+            public.clone().into(),
+        )
+        .await
+        .unwrap();
+    assert!(client
+        .rpc()
+        .has_key(public.clone().into(), "aura".to_string())
+        .await
+        .unwrap());
+}
+
+#[tokio::test]
+async fn fetch_block_hash() {
+    let node_process = test_node_process().await;
+    node_process.client().rpc().block_hash(None).await.unwrap();
+}
+
+#[tokio::test]
+async fn fetch_block() {
+    let node_process = test_node_process().await;
+    let client = node_process.client();
+    let block_hash = client.rpc().block_hash(None).await.unwrap();
+    client.rpc().block(block_hash).await.unwrap();
+}
+
+#[tokio::test]
+async fn fetch_read_proof() {
+    let node_process = test_node_process().await;
+    let client = node_process.client();
+    let block_hash = client.rpc().block_hash(None).await.unwrap();
+    client
+        .rpc()
+        .read_proof(
+            vec![
+                StorageKey(well_known_keys::HEAP_PAGES.to_vec()),
+                StorageKey(well_known_keys::EXTRINSIC_INDEX.to_vec()),
+            ],
+            block_hash,
+        )
+        .await
+        .unwrap();
+}
+
+#[tokio::test]
+async fn chain_subscribe_blocks() {
+    let node_process = test_node_process().await;
+    let client = node_process.client();
+    let mut blocks = client.rpc().subscribe_blocks().await.unwrap();
+    blocks.next().await.unwrap().unwrap();
+}
+
+#[tokio::test]
+async fn chain_subscribe_finalized_blocks() {
+    let node_process = test_node_process().await;
+    let client = node_process.client();
+    let mut blocks = client.rpc().subscribe_finalized_blocks().await.unwrap();
+    blocks.next().await.unwrap().unwrap();
+}
+
+#[tokio::test]
+async fn fetch_keys() {
+    let node_process = test_node_process().await;
+    let client = node_process.client();
+    let keys = client
+        .storage()
+        .fetch_keys::<system::storage::Account>(4, None, None)
+        .await
+        .unwrap();
+    assert_eq!(keys.len(), 4)
+}
+
+#[tokio::test]
+async fn test_iter() {
+    let node_process = test_node_process().await;
+    let client = node_process.client();
+    let mut iter = client
+        .storage()
+        .iter::<system::storage::Account>(None)
+        .await
+        .unwrap();
+    let mut i = 0;
+    while iter.next().await.unwrap().is_some() {
+        i += 1;
+    }
+    assert_eq!(i, 13);
+}
+
+#[tokio::test]
+async fn fetch_system_info() {
+    let node_process = test_node_process().await;
+    let client = node_process.client();
+    assert_eq!(client.rpc().system_chain().await.unwrap(), "Development");
+    assert_eq!(client.rpc().system_name().await.unwrap(), "Substrate Node");
+    assert!(!client.rpc().system_version().await.unwrap().is_empty());
+}

testing/integration-tests/src/codegen/mod.rs

@@ -0,0 +1,26 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+/// Checks that code generated by `subxt-cli codegen` compiles. Allows inspection of compiler errors
+/// directly, more accurately than via the macro and `cargo expand`.
+///
+/// Generate by:
+///
+/// - run `polkadot --dev --tmp` node locally
+/// - `cargo run --release -p subxt-cli -- codegen | rustfmt > integration-tests/src/codegen/polkadot.rs`
+#[rustfmt::skip]
+#[allow(clippy::all)]
+mod polkadot;

testing/integration-tests/src/events/mod.rs

@@ -0,0 +1,230 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+    node_runtime::{
+        balances,
+        system,
+    },
+    pair_signer,
+    test_context,
+};
+use futures::StreamExt;
+use sp_keyring::AccountKeyring;
+
+// Check that we can subscribe to non-finalized block events.
+#[tokio::test]
+async fn non_finalized_block_subscription() -> Result<(), subxt::BasicError> {
+    tracing_subscriber::fmt::try_init().ok();
+    let ctx = test_context().await;
+
+    let mut event_sub = ctx.api.events().subscribe().await?;
+
+    // Wait for the next set of events, and check that the
+    // associated block hash is not finalized yet.
+    let events = event_sub.next().await.unwrap()?;
+    let event_block_hash = events.block_hash();
+    let current_block_hash = ctx.api.client.rpc().block_hash(None).await?.unwrap();
+
+    assert_eq!(event_block_hash, current_block_hash);
+    Ok(())
+}
+
+// Check that we can subscribe to finalized block events.
+#[tokio::test]
+async fn finalized_block_subscription() -> Result<(), subxt::BasicError> {
+    tracing_subscriber::fmt::try_init().ok();
+    let ctx = test_context().await;
+
+    let mut event_sub = ctx.api.events().subscribe_finalized().await?;
+
+    // Wait for the next set of events, and check that the
+    // associated block hash is the one we just finalized.
+    // (this can be a bit slow as we have to wait for finalization)
+    let events = event_sub.next().await.unwrap()?;
+    let event_block_hash = events.block_hash();
+    let finalized_hash = ctx.api.client.rpc().finalized_head().await?;
+
+    assert_eq!(event_block_hash, finalized_hash);
+    Ok(())
+}
+
+// Check that our subscription actually keeps producing events for
+// a few blocks.
+#[tokio::test]
+async fn subscription_produces_events_each_block() -> Result<(), subxt::BasicError> {
+    tracing_subscriber::fmt::try_init().ok();
+    let ctx = test_context().await;
+
+    let mut event_sub = ctx.api.events().subscribe().await?;
+
+    for i in 0..3 {
+        let events = event_sub
+            .next()
+            .await
+            .expect("events expected each block")?;
+        let success_event = events
+            .find_first::<system::events::ExtrinsicSuccess>()
+            .expect("decode error");
+        // Every now and then I get no bytes back for the first block events;
+        // I assume that this might be the case for the genesis block, so don't
+        // worry if no event found (but we should have no decode errors etc either way).
+        if i > 0 && success_event.is_none() {
+            let n = events.len();
+            panic!("Expected an extrinsic success event on iteration {i} (saw {n} other events)")
+        }
+    }
+
+    Ok(())
+}
+
+// Check that our subscription receives events, and we can filter them based on
+// it's Stream impl, and ultimately see the event we expect.
+#[tokio::test]
+async fn balance_transfer_subscription() -> Result<(), subxt::BasicError> {
+    tracing_subscriber::fmt::try_init().ok();
+    let ctx = test_context().await;
+
+    // Subscribe to balance transfer events, ignoring all else.
+    let event_sub = ctx
+        .api
+        .events()
+        .subscribe()
+        .await?
+        .filter_events::<(balances::events::Transfer,)>();
+
+    // Calling `.next()` on the above borrows it, and the `filter_map`
+    // means it's no longer `Unpin`, so we pin it on the stack:
+    futures::pin_mut!(event_sub);
+
+    // Make a transfer:
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let bob = AccountKeyring::Bob.to_account_id();
+    ctx.api
+        .tx()
+        .balances()
+        .transfer(bob.clone().into(), 10_000)?
+        .sign_and_submit_then_watch_default(&alice)
+        .await?;
+
+    // Wait for the next balance transfer event in our subscription stream
+    // and check that it lines up:
+    let event = event_sub.next().await.unwrap().unwrap().event;
+    assert_eq!(
+        event,
+        balances::events::Transfer {
+            from: alice.account_id().clone(),
+            to: bob.clone(),
+            amount: 10_000
+        }
+    );
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn missing_block_headers_will_be_filled_in() -> Result<(), subxt::BasicError> {
+    // This function is not publically available to use, but contains
+    // the key logic for filling in missing blocks, so we want to test it.
+    // This is used in `subscribe_finalized` to ensure no block headers are
+    // missed.
+    use subxt::events::subscribe_to_block_headers_filling_in_gaps;
+
+    let ctx = test_context().await;
+
+    // Manually subscribe to the next 6 finalized block headers, but deliberately
+    // filter out some in the middle so we get back b _ _ b _ b. This guarantees
+    // that there will be some gaps, even if there aren't any from the subscription.
+    let some_finalized_blocks = ctx
+        .api
+        .client
+        .rpc()
+        .subscribe_finalized_blocks()
+        .await?
+        .enumerate()
+        .take(6)
+        .filter(|(n, _)| {
+            let n = *n;
+            async move { n == 0 || n == 3 || n == 5 }
+        })
+        .map(|(_, h)| h);
+
+    // This should spot any gaps in the middle and fill them back in.
+    let all_finalized_blocks = subscribe_to_block_headers_filling_in_gaps(
+        &ctx.api.client,
+        None,
+        some_finalized_blocks,
+    );
+    futures::pin_mut!(all_finalized_blocks);
+
+    // Iterate the block headers, making sure we get them all in order.
+    let mut last_block_number = None;
+    while let Some(header) = all_finalized_blocks.next().await {
+        let header = header?;
+
+        use sp_runtime::traits::Header;
+        let block_number: u128 = (*header.number()).into();
+
+        if let Some(last) = last_block_number {
+            assert_eq!(last + 1, block_number);
+        }
+        last_block_number = Some(block_number);
+    }
+
+    Ok(())
+}
+
+// This is just a compile-time check that we can subscribe to events in
+// a context that requires the event subscription/filtering to be Send-able.
+// We test a typical use of EventSubscription and FilterEvents. We don't need
+// to run this code; just check that it compiles.
+#[allow(unused)]
+async fn check_events_are_sendable() {
+    // check that EventSubscription can be used across await points.
+    tokio::task::spawn(async {
+        let ctx = test_context().await;
+
+        let mut event_sub = ctx.api.events().subscribe().await?;
+
+        while let Some(ev) = event_sub.next().await {
+            // if `event_sub` doesn't implement Send, we can't hold
+            // it across an await point inside of a tokio::spawn, which
+            // requires Send. This will lead to a compile error.
+        }
+
+        Ok::<_, subxt::BasicError>(())
+    });
+
+    // Check that FilterEvents can be used across await points.
+    tokio::task::spawn(async {
+        let ctx = test_context().await;
+
+        let mut event_sub = ctx
+            .api
+            .events()
+            .subscribe()
+            .await?
+            .filter_events::<(balances::events::Transfer,)>();
+
+        while let Some(ev) = event_sub.next().await {
+            // if `event_sub` doesn't implement Send, we can't hold
+            // it across an await point inside of a tokio::spawn, which
+            // requires Send; This will lead to a compile error.
+        }
+
+        Ok::<_, subxt::BasicError>(())
+    });
+}

testing/integration-tests/src/frame/balances.rs

@@ -0,0 +1,282 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+    node_runtime::{
+        balances,
+        runtime_types,
+        system,
+        DispatchError,
+    },
+    pair_signer,
+    test_context,
+};
+use codec::Decode;
+use sp_core::{
+    sr25519::Pair,
+    Pair as _,
+};
+use sp_keyring::AccountKeyring;
+use sp_runtime::{
+    AccountId32,
+    MultiAddress,
+};
+use subxt::Error;
+
+#[tokio::test]
+async fn tx_basic_transfer() -> Result<(), subxt::Error<DispatchError>> {
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let bob = pair_signer(AccountKeyring::Bob.pair());
+    let bob_address = bob.account_id().clone().into();
+    let cxt = test_context().await;
+    let api = &cxt.api;
+
+    let alice_pre = api
+        .storage()
+        .system()
+        .account(alice.account_id(), None)
+        .await?;
+    let bob_pre = api
+        .storage()
+        .system()
+        .account(bob.account_id(), None)
+        .await?;
+
+    let events = api
+        .tx()
+        .balances()
+        .transfer(bob_address, 10_000)?
+        .sign_and_submit_then_watch_default(&alice)
+        .await?
+        .wait_for_finalized_success()
+        .await?;
+    let event = events
+        .find_first::<balances::events::Transfer>()
+        .expect("Failed to decode balances::events::Transfer")
+        .expect("Failed to find balances::events::Transfer");
+    let _extrinsic_success = events
+        .find_first::<system::events::ExtrinsicSuccess>()
+        .expect("Failed to decode ExtrinisicSuccess")
+        .expect("Failed to find ExtrinisicSuccess");
+
+    let expected_event = balances::events::Transfer {
+        from: alice.account_id().clone(),
+        to: bob.account_id().clone(),
+        amount: 10_000,
+    };
+    assert_eq!(event, expected_event);
+
+    let alice_post = api
+        .storage()
+        .system()
+        .account(alice.account_id(), None)
+        .await?;
+    let bob_post = api
+        .storage()
+        .system()
+        .account(bob.account_id(), None)
+        .await?;
+
+    assert!(alice_pre.data.free - 10_000 >= alice_post.data.free);
+    assert_eq!(bob_pre.data.free + 10_000, bob_post.data.free);
+    Ok(())
+}
+
+#[tokio::test]
+async fn multiple_transfers_work_nonce_incremented(
+) -> Result<(), subxt::Error<DispatchError>> {
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let bob = pair_signer(AccountKeyring::Bob.pair());
+    let bob_address: MultiAddress<AccountId32, u32> = bob.account_id().clone().into();
+    let cxt = test_context().await;
+    let api = &cxt.api;
+
+    let bob_pre = api
+        .storage()
+        .system()
+        .account(bob.account_id(), None)
+        .await?;
+
+    for _ in 0..3 {
+        api
+            .tx()
+            .balances()
+            .transfer(bob_address.clone(), 10_000)?
+            .sign_and_submit_then_watch_default(&alice)
+            .await?
+            .wait_for_in_block() // Don't need to wait for finalization; this is quicker.
+            .await?
+            .wait_for_success()
+            .await?;
+    }
+
+    let bob_post = api
+        .storage()
+        .system()
+        .account(bob.account_id(), None)
+        .await?;
+
+    assert_eq!(bob_pre.data.free + 30_000, bob_post.data.free);
+    Ok(())
+}
+
+#[tokio::test]
+async fn storage_total_issuance() {
+    let cxt = test_context().await;
+    let total_issuance = cxt
+        .api
+        .storage()
+        .balances()
+        .total_issuance(None)
+        .await
+        .unwrap();
+    assert_ne!(total_issuance, 0);
+}
+
+#[tokio::test]
+async fn storage_balance_lock() -> Result<(), subxt::Error<DispatchError>> {
+    let bob = pair_signer(AccountKeyring::Bob.pair());
+    let charlie = AccountKeyring::Charlie.to_account_id();
+    let cxt = test_context().await;
+
+    cxt.api
+        .tx()
+        .staking()
+        .bond(
+            charlie.into(),
+            100_000_000_000_000,
+            runtime_types::pallet_staking::RewardDestination::Stash,
+        )?
+        .sign_and_submit_then_watch_default(&bob)
+        .await?
+        .wait_for_finalized_success()
+        .await?
+        .find_first::<system::events::ExtrinsicSuccess>()?
+        .expect("No ExtrinsicSuccess Event found");
+
+    let locked_account = AccountKeyring::Bob.to_account_id();
+    let locks = cxt
+        .api
+        .storage()
+        .balances()
+        .locks(&locked_account, None)
+        .await?;
+
+    assert_eq!(
+        locks.0,
+        vec![runtime_types::pallet_balances::BalanceLock {
+            id: *b"staking ",
+            amount: 100_000_000_000_000,
+            reasons: runtime_types::pallet_balances::Reasons::All,
+        }]
+    );
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn transfer_error() {
+    tracing_subscriber::fmt::try_init().ok();
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let alice_addr = alice.account_id().clone().into();
+    let hans = pair_signer(Pair::generate().0);
+    let hans_address = hans.account_id().clone().into();
+    let ctx = test_context().await;
+
+    ctx.api
+        .tx()
+        .balances()
+        .transfer(hans_address, 100_000_000_000_000_000)
+        .unwrap()
+        .sign_and_submit_then_watch_default(&alice)
+        .await
+        .unwrap()
+        .wait_for_finalized_success()
+        .await
+        .unwrap();
+
+    let res = ctx
+        .api
+        .tx()
+        .balances()
+        .transfer(alice_addr, 100_000_000_000_000_000)
+        .unwrap()
+        .sign_and_submit_then_watch_default(&hans)
+        .await
+        .unwrap()
+        .wait_for_finalized_success()
+        .await;
+
+    if let Err(Error::Module(err)) = res {
+        assert_eq!(err.pallet, "Balances");
+        assert_eq!(err.error, "InsufficientBalance");
+    } else {
+        panic!("expected a runtime module error");
+    }
+}
+
+#[tokio::test]
+async fn transfer_implicit_subscription() {
+    tracing_subscriber::fmt::try_init().ok();
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let bob = AccountKeyring::Bob.to_account_id();
+    let bob_addr = bob.clone().into();
+    let cxt = test_context().await;
+
+    let event = cxt
+        .api
+        .tx()
+        .balances()
+        .transfer(bob_addr, 10_000)
+        .unwrap()
+        .sign_and_submit_then_watch_default(&alice)
+        .await
+        .unwrap()
+        .wait_for_finalized_success()
+        .await
+        .unwrap()
+        .find_first::<balances::events::Transfer>()
+        .expect("Can decode events")
+        .expect("Can find balance transfer event");
+
+    assert_eq!(
+        event,
+        balances::events::Transfer {
+            from: alice.account_id().clone(),
+            to: bob.clone(),
+            amount: 10_000
+        }
+    );
+}
+
+#[tokio::test]
+async fn constant_existential_deposit() {
+    let cxt = test_context().await;
+    let locked_metadata = cxt.client().metadata();
+    let metadata = locked_metadata.read();
+    let balances_metadata = metadata.pallet("Balances").unwrap();
+    let constant_metadata = balances_metadata.constant("ExistentialDeposit").unwrap();
+    let existential_deposit = u128::decode(&mut &constant_metadata.value[..]).unwrap();
+    assert_eq!(existential_deposit, 100_000_000_000_000);
+    assert_eq!(
+        existential_deposit,
+        cxt.api
+            .constants()
+            .balances()
+            .existential_deposit()
+            .unwrap()
+    );
+}

testing/integration-tests/src/frame/contracts.rs

@@ -0,0 +1,228 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use sp_keyring::AccountKeyring;
+
+use crate::{
+    node_runtime::{
+        self,
+        contracts::{
+            calls::TransactionApi,
+            events,
+            storage,
+        },
+        system,
+        DispatchError,
+    },
+    test_context,
+    NodeRuntimeParams,
+    TestContext,
+};
+use sp_core::sr25519::Pair;
+use sp_runtime::MultiAddress;
+use subxt::{
+    Client,
+    Config,
+    DefaultConfig,
+    Error,
+    PairSigner,
+    TransactionProgress,
+};
+
+struct ContractsTestContext {
+    cxt: TestContext,
+    signer: PairSigner<DefaultConfig, Pair>,
+}
+
+type Hash = <DefaultConfig as Config>::Hash;
+type AccountId = <DefaultConfig as Config>::AccountId;
+
+impl ContractsTestContext {
+    async fn init() -> Self {
+        tracing_subscriber::fmt::try_init().ok();
+        let cxt = test_context().await;
+        let signer = PairSigner::new(AccountKeyring::Alice.pair());
+
+        Self { cxt, signer }
+    }
+
+    fn client(&self) -> &Client<DefaultConfig> {
+        self.cxt.client()
+    }
+
+    fn contracts_tx(&self) -> TransactionApi<DefaultConfig, NodeRuntimeParams> {
+        self.cxt.api.tx().contracts()
+    }
+
+    async fn instantiate_with_code(
+        &self,
+    ) -> Result<(Hash, AccountId), Error<DispatchError>> {
+        tracing::info!("instantiate_with_code:");
+        const CONTRACT: &str = r#"
+                (module
+                    (func (export "call"))
+                    (func (export "deploy"))
+                )
+            "#;
+        let code = wabt::wat2wasm(CONTRACT).expect("invalid wabt");
+
+        let events = self
+            .cxt
+            .api
+            .tx()
+            .contracts()
+            .instantiate_with_code(
+                100_000_000_000_000_000, // endowment
+                500_000_000_000,         // gas_limit
+                None,                    // storage_deposit_limit
+                code,
+                vec![], // data
+                vec![], // salt
+            )?
+            .sign_and_submit_then_watch_default(&self.signer)
+            .await?
+            .wait_for_finalized_success()
+            .await?;
+
+        let code_stored = events
+            .find_first::<events::CodeStored>()?
+            .ok_or_else(|| Error::Other("Failed to find a CodeStored event".into()))?;
+        let instantiated = events
+            .find_first::<events::Instantiated>()?
+            .ok_or_else(|| Error::Other("Failed to find a Instantiated event".into()))?;
+        let _extrinsic_success = events
+            .find_first::<system::events::ExtrinsicSuccess>()?
+            .ok_or_else(|| {
+                Error::Other("Failed to find a ExtrinsicSuccess event".into())
+            })?;
+
+        tracing::info!("  Block hash: {:?}", events.block_hash());
+        tracing::info!("  Code hash: {:?}", code_stored.code_hash);
+        tracing::info!("  Contract address: {:?}", instantiated.contract);
+        Ok((code_stored.code_hash, instantiated.contract))
+    }
+
+    async fn instantiate(
+        &self,
+        code_hash: Hash,
+        data: Vec<u8>,
+        salt: Vec<u8>,
+    ) -> Result<AccountId, Error<DispatchError>> {
+        // call instantiate extrinsic
+        let result = self
+            .contracts_tx()
+            .instantiate(
+                100_000_000_000_000_000, // endowment
+                500_000_000_000,         // gas_limit
+                None,                    // storage_deposit_limit
+                code_hash,
+                data,
+                salt,
+            )?
+            .sign_and_submit_then_watch_default(&self.signer)
+            .await?
+            .wait_for_finalized_success()
+            .await?;
+
+        tracing::info!("Instantiate result: {:?}", result);
+        let instantiated = result
+            .find_first::<events::Instantiated>()?
+            .ok_or_else(|| Error::Other("Failed to find a Instantiated event".into()))?;
+
+        Ok(instantiated.contract)
+    }
+
+    async fn call(
+        &self,
+        contract: AccountId,
+        input_data: Vec<u8>,
+    ) -> Result<
+        TransactionProgress<'_, DefaultConfig, DispatchError, node_runtime::Event>,
+        Error<DispatchError>,
+    > {
+        tracing::info!("call: {:?}", contract);
+        let result = self
+            .contracts_tx()
+            .call(
+                MultiAddress::Id(contract),
+                0,           // value
+                500_000_000, // gas_limit
+                None,        // storage_deposit_limit
+                input_data,
+            )?
+            .sign_and_submit_then_watch_default(&self.signer)
+            .await?;
+
+        tracing::info!("Call result: {:?}", result);
+        Ok(result)
+    }
+}
+
+#[tokio::test]
+async fn tx_instantiate_with_code() {
+    let ctx = ContractsTestContext::init().await;
+    let result = ctx.instantiate_with_code().await;
+
+    assert!(
+        result.is_ok(),
+        "Error calling instantiate_with_code and receiving CodeStored and Instantiated Events: {:?}",
+        result
+    );
+}
+
+#[tokio::test]
+async fn tx_instantiate() {
+    let ctx = ContractsTestContext::init().await;
+    let (code_hash, _) = ctx.instantiate_with_code().await.unwrap();
+
+    let instantiated = ctx.instantiate(code_hash, vec![], vec![1u8]).await;
+
+    assert!(
+        instantiated.is_ok(),
+        "Error instantiating contract: {:?}",
+        instantiated
+    );
+}
+
+#[tokio::test]
+async fn tx_call() {
+    let cxt = ContractsTestContext::init().await;
+    let (_, contract) = cxt.instantiate_with_code().await.unwrap();
+
+    let contract_info = cxt
+        .cxt
+        .api
+        .storage()
+        .contracts()
+        .contract_info_of(&contract, None)
+        .await;
+    assert!(contract_info.is_ok());
+
+    let keys = cxt
+        .client()
+        .storage()
+        .fetch_keys::<storage::ContractInfoOf>(5, None, None)
+        .await
+        .unwrap()
+        .iter()
+        .map(|key| hex::encode(&key.0))
+        .collect::<Vec<_>>();
+    println!("keys post: {:?}", keys);
+
+    let executed = cxt.call(contract, vec![]).await;
+
+    assert!(executed.is_ok(), "Error calling contract: {:?}", executed);
+}

testing/integration-tests/src/frame/mod.rs

@@ -0,0 +1,24 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Test interactions with some built-in FRAME pallets.
+
+mod balances;
+mod contracts;
+mod staking;
+mod sudo;
+mod system;
+mod timestamp;

testing/integration-tests/src/frame/staking.rs

@@ -0,0 +1,262 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+    node_runtime::{
+        runtime_types::pallet_staking::{
+            RewardDestination,
+            ValidatorPrefs,
+        },
+        staking,
+        DispatchError,
+    },
+    pair_signer,
+    test_context,
+};
+use assert_matches::assert_matches;
+use sp_core::{
+    sr25519,
+    Pair,
+};
+use sp_keyring::AccountKeyring;
+use subxt::Error;
+
+/// Helper function to generate a crypto pair from seed
+fn get_from_seed(seed: &str) -> sr25519::Pair {
+    sr25519::Pair::from_string(&format!("//{}", seed), None)
+        .expect("static values are valid; qed")
+}
+
+fn default_validator_prefs() -> ValidatorPrefs {
+    ValidatorPrefs {
+        commission: sp_runtime::Perbill::default(),
+        blocked: false,
+    }
+}
+
+#[tokio::test]
+async fn validate_with_controller_account() {
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let ctx = test_context().await;
+    ctx.api
+        .tx()
+        .staking()
+        .validate(default_validator_prefs())
+        .unwrap()
+        .sign_and_submit_then_watch_default(&alice)
+        .await
+        .unwrap()
+        .wait_for_finalized_success()
+        .await
+        .expect("should be successful");
+}
+
+#[tokio::test]
+async fn validate_not_possible_for_stash_account() -> Result<(), Error<DispatchError>> {
+    let alice_stash = pair_signer(get_from_seed("Alice//stash"));
+    let ctx = test_context().await;
+    let announce_validator = ctx
+        .api
+        .tx()
+        .staking()
+        .validate(default_validator_prefs())?
+        .sign_and_submit_then_watch_default(&alice_stash)
+        .await?
+        .wait_for_finalized_success()
+        .await;
+    assert_matches!(announce_validator, Err(Error::Module(err)) => {
+        assert_eq!(err.pallet, "Staking");
+        assert_eq!(err.error, "NotController");
+    });
+    Ok(())
+}
+
+#[tokio::test]
+async fn nominate_with_controller_account() {
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let bob = pair_signer(AccountKeyring::Bob.pair());
+    let ctx = test_context().await;
+
+    ctx.api
+        .tx()
+        .staking()
+        .nominate(vec![bob.account_id().clone().into()])
+        .unwrap()
+        .sign_and_submit_then_watch_default(&alice)
+        .await
+        .unwrap()
+        .wait_for_finalized_success()
+        .await
+        .expect("should be successful");
+}
+
+#[tokio::test]
+async fn nominate_not_possible_for_stash_account() -> Result<(), Error<DispatchError>> {
+    let alice_stash = pair_signer(get_from_seed("Alice//stash"));
+    let bob = pair_signer(AccountKeyring::Bob.pair());
+    let ctx = test_context().await;
+
+    let nomination = ctx
+        .api
+        .tx()
+        .staking()
+        .nominate(vec![bob.account_id().clone().into()])?
+        .sign_and_submit_then_watch_default(&alice_stash)
+        .await?
+        .wait_for_finalized_success()
+        .await;
+
+    assert_matches!(nomination, Err(Error::Module(err)) => {
+        assert_eq!(err.pallet, "Staking");
+        assert_eq!(err.error, "NotController");
+    });
+    Ok(())
+}
+
+#[tokio::test]
+async fn chill_works_for_controller_only() -> Result<(), Error<DispatchError>> {
+    let alice_stash = pair_signer(get_from_seed("Alice//stash"));
+    let bob_stash = pair_signer(get_from_seed("Bob//stash"));
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let ctx = test_context().await;
+
+    // this will fail the second time, which is why this is one test, not two
+    ctx.api
+        .tx()
+        .staking()
+        .nominate(vec![bob_stash.account_id().clone().into()])?
+        .sign_and_submit_then_watch_default(&alice)
+        .await?
+        .wait_for_finalized_success()
+        .await?;
+
+    let ledger = ctx
+        .api
+        .storage()
+        .staking()
+        .ledger(alice.account_id(), None)
+        .await?
+        .unwrap();
+    assert_eq!(alice_stash.account_id(), &ledger.stash);
+
+    let chill = ctx
+        .api
+        .tx()
+        .staking()
+        .chill()?
+        .sign_and_submit_then_watch_default(&alice_stash)
+        .await?
+        .wait_for_finalized_success()
+        .await;
+
+    assert_matches!(chill, Err(Error::Module(err)) => {
+        assert_eq!(err.pallet, "Staking");
+        assert_eq!(err.error, "NotController");
+    });
+
+    let is_chilled = ctx
+        .api
+        .tx()
+        .staking()
+        .chill()?
+        .sign_and_submit_then_watch_default(&alice)
+        .await?
+        .wait_for_finalized_success()
+        .await?
+        .has::<staking::events::Chilled>()?;
+    assert!(is_chilled);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn tx_bond() -> Result<(), Error<DispatchError>> {
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let ctx = test_context().await;
+
+    let bond = ctx
+        .api
+        .tx()
+        .staking()
+        .bond(
+            AccountKeyring::Bob.to_account_id().into(),
+            100_000_000_000_000,
+            RewardDestination::Stash,
+        )
+        .unwrap()
+        .sign_and_submit_then_watch_default(&alice)
+        .await?
+        .wait_for_finalized_success()
+        .await;
+
+    assert!(bond.is_ok());
+
+    let bond_again = ctx
+        .api
+        .tx()
+        .staking()
+        .bond(
+            AccountKeyring::Bob.to_account_id().into(),
+            100_000_000_000_000,
+            RewardDestination::Stash,
+        )
+        .unwrap()
+        .sign_and_submit_then_watch_default(&alice)
+        .await?
+        .wait_for_finalized_success()
+        .await;
+
+    assert_matches!(bond_again, Err(Error::Module(err)) => {
+        assert_eq!(err.pallet, "Staking");
+        assert_eq!(err.error, "AlreadyBonded");
+    });
+    Ok(())
+}
+
+#[tokio::test]
+async fn storage_history_depth() -> Result<(), Error<DispatchError>> {
+    let ctx = test_context().await;
+    let history_depth = ctx.api.storage().staking().history_depth(None).await?;
+    assert_eq!(history_depth, 84);
+    Ok(())
+}
+
+#[tokio::test]
+async fn storage_current_era() -> Result<(), Error<DispatchError>> {
+    let ctx = test_context().await;
+    let _current_era = ctx
+        .api
+        .storage()
+        .staking()
+        .current_era(None)
+        .await?
+        .expect("current era always exists");
+    Ok(())
+}
+
+#[tokio::test]
+async fn storage_era_reward_points() -> Result<(), Error<DispatchError>> {
+    let cxt = test_context().await;
+    let current_era_result = cxt
+        .api
+        .storage()
+        .staking()
+        .eras_reward_points(&0, None)
+        .await;
+    assert!(current_era_result.is_ok());
+
+    Ok(())
+}

testing/integration-tests/src/frame/sudo.rs

@@ -0,0 +1,81 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+    node_runtime::{
+        runtime_types,
+        sudo,
+        DispatchError,
+    },
+    pair_signer,
+    test_context,
+};
+use sp_keyring::AccountKeyring;
+
+type Call = runtime_types::node_runtime::Call;
+type BalancesCall = runtime_types::pallet_balances::pallet::Call;
+
+#[tokio::test]
+async fn test_sudo() -> Result<(), subxt::Error<DispatchError>> {
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let bob = AccountKeyring::Bob.to_account_id().into();
+    let cxt = test_context().await;
+
+    let call = Call::Balances(BalancesCall::transfer {
+        dest: bob,
+        value: 10_000,
+    });
+
+    let found_event = cxt
+        .api
+        .tx()
+        .sudo()
+        .sudo(call)?
+        .sign_and_submit_then_watch_default(&alice)
+        .await?
+        .wait_for_finalized_success()
+        .await?
+        .has::<sudo::events::Sudid>()?;
+
+    assert!(found_event);
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_sudo_unchecked_weight() -> Result<(), subxt::Error<DispatchError>> {
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let bob = AccountKeyring::Bob.to_account_id().into();
+    let cxt = test_context().await;
+
+    let call = Call::Balances(BalancesCall::transfer {
+        dest: bob,
+        value: 10_000,
+    });
+
+    let found_event = cxt
+        .api
+        .tx()
+        .sudo()
+        .sudo_unchecked_weight(call, 0)?
+        .sign_and_submit_then_watch_default(&alice)
+        .await?
+        .wait_for_finalized_success()
+        .await?
+        .has::<sudo::events::Sudid>()?;
+
+    assert!(found_event);
+    Ok(())
+}

testing/integration-tests/src/frame/system.rs

@@ -0,0 +1,62 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+    node_runtime::{
+        system,
+        DispatchError,
+    },
+    pair_signer,
+    test_context,
+};
+use assert_matches::assert_matches;
+use sp_keyring::AccountKeyring;
+
+#[tokio::test]
+async fn storage_account() -> Result<(), subxt::Error<DispatchError>> {
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+
+    let cxt = test_context().await;
+    let account_info = cxt
+        .api
+        .storage()
+        .system()
+        .account(alice.account_id(), None)
+        .await;
+
+    assert_matches!(account_info, Ok(_));
+    Ok(())
+}
+
+#[tokio::test]
+async fn tx_remark_with_event() -> Result<(), subxt::Error<DispatchError>> {
+    let alice = pair_signer(AccountKeyring::Alice.pair());
+    let cxt = test_context().await;
+
+    let found_event = cxt
+        .api
+        .tx()
+        .system()
+        .remark_with_event(b"remarkable".to_vec())?
+        .sign_and_submit_then_watch_default(&alice)
+        .await?
+        .wait_for_finalized_success()
+        .await?
+        .has::<system::events::Remarked>()?;
+
+    assert!(found_event);
+    Ok(())
+}

testing/integration-tests/src/frame/timestamp.rs

@@ -0,0 +1,26 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::test_context;
+
+#[tokio::test]
+async fn storage_get_current_timestamp() {
+    let cxt = test_context().await;
+
+    let timestamp = cxt.api.storage().timestamp().now(None).await;
+
+    assert!(timestamp.is_ok())
+}

testing/integration-tests/src/lib.rs

@@ -0,0 +1,38 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+#![deny(unused_crate_dependencies)]
+
+#[cfg(test)]
+mod codegen;
+#[cfg(test)]
+mod utils;
+
+#[cfg(test)]
+mod client;
+#[cfg(test)]
+mod events;
+#[cfg(test)]
+mod frame;
+#[cfg(test)]
+mod metadata;
+#[cfg(test)]
+mod storage;
+
+#[cfg(test)]
+use test_runtime::node_runtime;
+#[cfg(test)]
+use utils::*;

testing/integration-tests/src/metadata/mod.rs

@@ -0,0 +1,17 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+mod validation;

testing/integration-tests/src/metadata/validation.rs

@@ -0,0 +1,340 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+    test_context,
+    TestContext,
+};
+use frame_metadata::{
+    ExtrinsicMetadata,
+    PalletCallMetadata,
+    PalletMetadata,
+    PalletStorageMetadata,
+    RuntimeMetadataPrefixed,
+    RuntimeMetadataV14,
+    StorageEntryMetadata,
+    StorageEntryModifier,
+    StorageEntryType,
+};
+use scale_info::{
+    build::{
+        Fields,
+        Variants,
+    },
+    meta_type,
+    Path,
+    Type,
+    TypeInfo,
+};
+use subxt::{
+    ClientBuilder,
+    DefaultConfig,
+    Metadata,
+    SubstrateExtrinsicParams,
+};
+
+use crate::utils::node_runtime;
+
+type RuntimeApi =
+    node_runtime::RuntimeApi<DefaultConfig, SubstrateExtrinsicParams<DefaultConfig>>;
+
+async fn metadata_to_api(metadata: RuntimeMetadataV14, cxt: &TestContext) -> RuntimeApi {
+    let prefixed = RuntimeMetadataPrefixed::from(metadata);
+    let metadata = Metadata::try_from(prefixed).unwrap();
+
+    ClientBuilder::new()
+            .set_url(cxt.node_proc.ws_url().to_string())
+            .set_metadata(metadata)
+            .build()
+            .await
+            .unwrap()
+            .to_runtime_api::<node_runtime::RuntimeApi<
+                DefaultConfig,
+                SubstrateExtrinsicParams<DefaultConfig>,
+            >>()
+}
+
+#[tokio::test]
+async fn full_metadata_check() {
+    let cxt = test_context().await;
+    let api = &cxt.api;
+
+    // Runtime metadata is identical to the metadata used during API generation.
+    assert!(api.validate_metadata().is_ok());
+
+    // Modify the metadata.
+    let mut metadata: RuntimeMetadataV14 = {
+        let locked_client_metadata = api.client.metadata();
+        let client_metadata = locked_client_metadata.read();
+        client_metadata.runtime_metadata().clone()
+    };
+    metadata.pallets[0].name = "NewPallet".to_string();
+
+    let new_api = metadata_to_api(metadata, &cxt).await;
+    assert_eq!(
+        new_api
+            .validate_metadata()
+            .err()
+            .expect("Validation should fail for incompatible metadata"),
+        ::subxt::MetadataError::IncompatibleMetadata
+    );
+}
+
+#[tokio::test]
+async fn constants_check() {
+    let cxt = test_context().await;
+    let api = &cxt.api;
+
+    // Ensure that `ExistentialDeposit` is compatible before altering the metadata.
+    assert!(cxt.api.constants().balances().existential_deposit().is_ok());
+
+    // Modify the metadata.
+    let mut metadata: RuntimeMetadataV14 = {
+        let locked_client_metadata = api.client.metadata();
+        let client_metadata = locked_client_metadata.read();
+        client_metadata.runtime_metadata().clone()
+    };
+
+    let mut existential = metadata
+        .pallets
+        .iter_mut()
+        .find(|pallet| pallet.name == "Balances")
+        .expect("Metadata must contain Balances pallet")
+        .constants
+        .iter_mut()
+        .find(|constant| constant.name == "ExistentialDeposit")
+        .expect("ExistentialDeposit constant must be present");
+    existential.value = vec![0u8; 32];
+
+    let new_api = metadata_to_api(metadata, &cxt).await;
+
+    assert!(new_api.validate_metadata().is_err());
+    assert!(new_api
+        .constants()
+        .balances()
+        .existential_deposit()
+        .is_err());
+
+    // Other constant validation should not be impacted.
+    assert!(new_api.constants().balances().max_locks().is_ok());
+}
+
+fn default_pallet() -> PalletMetadata {
+    PalletMetadata {
+        name: "Test",
+        storage: None,
+        calls: None,
+        event: None,
+        constants: vec![],
+        error: None,
+        index: 0,
+    }
+}
+
+fn pallets_to_metadata(pallets: Vec<PalletMetadata>) -> RuntimeMetadataV14 {
+    RuntimeMetadataV14::new(
+        pallets,
+        ExtrinsicMetadata {
+            ty: meta_type::<()>(),
+            version: 0,
+            signed_extensions: vec![],
+        },
+        meta_type::<()>(),
+    )
+}
+
+#[tokio::test]
+async fn calls_check() {
+    let cxt = test_context().await;
+
+    // Ensure that `Unbond` and `WinthdrawUnbonded` calls are compatible before altering the metadata.
+    assert!(cxt.api.tx().staking().unbond(123_456_789_012_345).is_ok());
+    assert!(cxt.api.tx().staking().withdraw_unbonded(10).is_ok());
+
+    // Reconstruct the `Staking` call as is.
+    struct CallRec;
+    impl TypeInfo for CallRec {
+        type Identity = Self;
+        fn type_info() -> Type {
+            Type::builder()
+                .path(Path::new("Call", "pallet_staking::pallet::pallet"))
+                .variant(
+                    Variants::new()
+                        .variant("unbond", |v| {
+                            v.index(0).fields(Fields::named().field(|f| {
+                                f.compact::<u128>()
+                                    .name("value")
+                                    .type_name("BalanceOf<T>")
+                            }))
+                        })
+                        .variant("withdraw_unbonded", |v| {
+                            v.index(1).fields(Fields::named().field(|f| {
+                                f.ty::<u32>().name("num_slashing_spans").type_name("u32")
+                            }))
+                        }),
+                )
+        }
+    }
+    let pallet = PalletMetadata {
+        name: "Staking",
+        calls: Some(PalletCallMetadata {
+            ty: meta_type::<CallRec>(),
+        }),
+        ..default_pallet()
+    };
+    let metadata = pallets_to_metadata(vec![pallet]);
+    let new_api = metadata_to_api(metadata, &cxt).await;
+    assert!(new_api.tx().staking().unbond(123_456_789_012_345).is_ok());
+    assert!(new_api.tx().staking().withdraw_unbonded(10).is_ok());
+
+    // Change `Unbond` call but leave the rest as is.
+    struct CallRecSecond;
+    impl TypeInfo for CallRecSecond {
+        type Identity = Self;
+        fn type_info() -> Type {
+            Type::builder()
+                .path(Path::new("Call", "pallet_staking::pallet::pallet"))
+                .variant(
+                    Variants::new()
+                        .variant("unbond", |v| {
+                            v.index(0).fields(Fields::named().field(|f| {
+                                // Is of type u32 instead of u128.
+                                f.compact::<u32>().name("value").type_name("BalanceOf<T>")
+                            }))
+                        })
+                        .variant("withdraw_unbonded", |v| {
+                            v.index(1).fields(Fields::named().field(|f| {
+                                f.ty::<u32>().name("num_slashing_spans").type_name("u32")
+                            }))
+                        }),
+                )
+        }
+    }
+    let pallet = PalletMetadata {
+        name: "Staking",
+        calls: Some(PalletCallMetadata {
+            ty: meta_type::<CallRecSecond>(),
+        }),
+        ..default_pallet()
+    };
+    let metadata = pallets_to_metadata(vec![pallet]);
+    let new_api = metadata_to_api(metadata, &cxt).await;
+    // Unbond call should fail, while withdraw_unbonded remains compatible.
+    assert!(new_api.tx().staking().unbond(123_456_789_012_345).is_err());
+    assert!(new_api.tx().staking().withdraw_unbonded(10).is_ok());
+}
+
+#[tokio::test]
+async fn storage_check() {
+    let cxt = test_context().await;
+
+    // Ensure that `ExtrinsicCount` and `EventCount` storages are compatible before altering the metadata.
+    assert!(cxt
+        .api
+        .storage()
+        .system()
+        .extrinsic_count(None)
+        .await
+        .is_ok());
+    assert!(cxt
+        .api
+        .storage()
+        .system()
+        .all_extrinsics_len(None)
+        .await
+        .is_ok());
+
+    // Reconstruct the storage.
+    let storage = PalletStorageMetadata {
+        prefix: "System",
+        entries: vec![
+            StorageEntryMetadata {
+                name: "ExtrinsicCount",
+                modifier: StorageEntryModifier::Optional,
+                ty: StorageEntryType::Plain(meta_type::<u32>()),
+                default: vec![0],
+                docs: vec![],
+            },
+            StorageEntryMetadata {
+                name: "AllExtrinsicsLen",
+                modifier: StorageEntryModifier::Optional,
+                ty: StorageEntryType::Plain(meta_type::<u32>()),
+                default: vec![0],
+                docs: vec![],
+            },
+        ],
+    };
+    let pallet = PalletMetadata {
+        name: "System",
+        storage: Some(storage),
+        ..default_pallet()
+    };
+    let metadata = pallets_to_metadata(vec![pallet]);
+    let new_api = metadata_to_api(metadata, &cxt).await;
+    assert!(new_api
+        .storage()
+        .system()
+        .extrinsic_count(None)
+        .await
+        .is_ok());
+    assert!(new_api
+        .storage()
+        .system()
+        .all_extrinsics_len(None)
+        .await
+        .is_ok());
+
+    // Reconstruct the storage while modifying ExtrinsicCount.
+    let storage = PalletStorageMetadata {
+        prefix: "System",
+        entries: vec![
+            StorageEntryMetadata {
+                name: "ExtrinsicCount",
+                modifier: StorageEntryModifier::Optional,
+                // Previously was u32.
+                ty: StorageEntryType::Plain(meta_type::<u8>()),
+                default: vec![0],
+                docs: vec![],
+            },
+            StorageEntryMetadata {
+                name: "AllExtrinsicsLen",
+                modifier: StorageEntryModifier::Optional,
+                ty: StorageEntryType::Plain(meta_type::<u32>()),
+                default: vec![0],
+                docs: vec![],
+            },
+        ],
+    };
+    let pallet = PalletMetadata {
+        name: "System",
+        storage: Some(storage),
+        ..default_pallet()
+    };
+    let metadata = pallets_to_metadata(vec![pallet]);
+    let new_api = metadata_to_api(metadata, &cxt).await;
+    assert!(new_api
+        .storage()
+        .system()
+        .extrinsic_count(None)
+        .await
+        .is_err());
+    assert!(new_api
+        .storage()
+        .system()
+        .all_extrinsics_len(None)
+        .await
+        .is_ok());
+}

testing/integration-tests/src/storage/mod.rs

@@ -0,0 +1,139 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+    node_runtime::{
+        self,
+        DispatchError,
+    },
+    pair_signer,
+    test_context,
+};
+use sp_keyring::AccountKeyring;
+
+#[tokio::test]
+async fn storage_plain_lookup() -> Result<(), subxt::Error<DispatchError>> {
+    let ctx = test_context().await;
+
+    // Look up a plain value. Wait long enough that we don't get the genesis block data,
+    // because it may have no storage associated with it.
+    tokio::time::sleep(std::time::Duration::from_secs(6)).await;
+    let entry = ctx.api.storage().timestamp().now(None).await?;
+    assert!(entry > 0);
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn storage_map_lookup() -> Result<(), subxt::Error<DispatchError>> {
+    let ctx = test_context().await;
+
+    let signer = pair_signer(AccountKeyring::Alice.pair());
+    let alice = AccountKeyring::Alice.to_account_id();
+
+    // Do some transaction to bump the Alice nonce to 1:
+    ctx.api
+        .tx()
+        .system()
+        .remark(vec![1, 2, 3, 4, 5])?
+        .sign_and_submit_then_watch_default(&signer)
+        .await?
+        .wait_for_finalized_success()
+        .await?;
+
+    // Look up the nonce for the user (we expect it to be 1).
+    let entry = ctx.api.storage().system().account(&alice, None).await?;
+    assert_eq!(entry.nonce, 1);
+
+    Ok(())
+}
+
+// This fails until the fix in https://github.com/paritytech/subxt/pull/458 is introduced.
+// Here we create a key that looks a bit like a StorageNMap key, but should in fact be
+// treated as a StorageKey (ie we should hash both values together with one hasher, rather
+// than hash both values separately, or ignore the second value).
+#[tokio::test]
+async fn storage_n_mapish_key_is_properly_created(
+) -> Result<(), subxt::Error<DispatchError>> {
+    use codec::Encode;
+    use node_runtime::{
+        runtime_types::sp_core::crypto::KeyTypeId,
+        session::storage::KeyOwner,
+    };
+    use subxt::{
+        storage::StorageKeyPrefix,
+        StorageEntry,
+    };
+
+    // This is what the generated code hashes a `session().key_owner(..)` key into:
+    let actual_key_bytes = KeyOwner(&KeyTypeId([1, 2, 3, 4]), &[5u8, 6, 7, 8])
+        .key()
+        .final_key(StorageKeyPrefix::new::<KeyOwner>())
+        .0;
+
+    // Let's manually hash to what we assume it should be and compare:
+    let expected_key_bytes = {
+        // Hash the prefix to the storage entry:
+        let mut bytes = sp_core::twox_128("Session".as_bytes()).to_vec();
+        bytes.extend(&sp_core::twox_128("KeyOwner".as_bytes())[..]);
+        // twox64_concat a *tuple* of the args expected:
+        let suffix = (KeyTypeId([1, 2, 3, 4]), vec![5u8, 6, 7, 8]).encode();
+        bytes.extend(&sp_core::twox_64(&suffix));
+        bytes.extend(&suffix);
+        bytes
+    };
+
+    assert_eq!(actual_key_bytes, expected_key_bytes);
+    Ok(())
+}
+
+#[tokio::test]
+async fn storage_n_map_storage_lookup() -> Result<(), subxt::Error<DispatchError>> {
+    let ctx = test_context().await;
+
+    // Boilerplate; we create a new asset class with ID 99, and then
+    // we "approveTransfer" of some of this asset class. This gives us an
+    // entry in the `Approvals` StorageNMap that we can try to look up.
+    let signer = pair_signer(AccountKeyring::Alice.pair());
+    let alice = AccountKeyring::Alice.to_account_id();
+    let bob = AccountKeyring::Bob.to_account_id();
+    ctx.api
+        .tx()
+        .assets()
+        .create(99, alice.clone().into(), 1)?
+        .sign_and_submit_then_watch_default(&signer)
+        .await?
+        .wait_for_finalized_success()
+        .await?;
+    ctx.api
+        .tx()
+        .assets()
+        .approve_transfer(99, bob.clone().into(), 123)?
+        .sign_and_submit_then_watch_default(&signer)
+        .await?
+        .wait_for_finalized_success()
+        .await?;
+
+    // The actual test; look up this approval in storage:
+    let entry = ctx
+        .api
+        .storage()
+        .assets()
+        .approvals(&99, &alice, &bob, None)
+        .await?;
+    assert_eq!(entry.map(|a| a.amount), Some(123));
+    Ok(())
+}

testing/integration-tests/src/utils/context.rs

@@ -0,0 +1,78 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+pub(crate) use crate::{
+    node_runtime,
+    TestNodeProcess,
+};
+
+use sp_core::sr25519::Pair;
+use sp_keyring::AccountKeyring;
+use subxt::{
+    Client,
+    DefaultConfig,
+    PairSigner,
+    SubstrateExtrinsicParams,
+};
+
+/// substrate node should be installed on the $PATH
+const SUBSTRATE_NODE_PATH: &str = "substrate";
+
+pub type NodeRuntimeParams = SubstrateExtrinsicParams<DefaultConfig>;
+
+pub async fn test_node_process_with(
+    key: AccountKeyring,
+) -> TestNodeProcess<DefaultConfig> {
+    let path = std::env::var("SUBSTRATE_NODE_PATH").unwrap_or_else(|_| {
+        if which::which(SUBSTRATE_NODE_PATH).is_err() {
+            panic!("A substrate binary should be installed on your path for integration tests. \
+            See https://github.com/paritytech/subxt/tree/master#integration-testing")
+        }
+        SUBSTRATE_NODE_PATH.to_string()
+    });
+
+    let proc = TestNodeProcess::<DefaultConfig>::build(path.as_str())
+        .with_authority(key)
+        .spawn::<DefaultConfig>()
+        .await;
+    proc.unwrap()
+}
+
+pub async fn test_node_process() -> TestNodeProcess<DefaultConfig> {
+    test_node_process_with(AccountKeyring::Alice).await
+}
+
+pub struct TestContext {
+    pub node_proc: TestNodeProcess<DefaultConfig>,
+    pub api: node_runtime::RuntimeApi<DefaultConfig, NodeRuntimeParams>,
+}
+
+impl TestContext {
+    pub fn client(&self) -> &Client<DefaultConfig> {
+        &self.api.client
+    }
+}
+
+pub async fn test_context() -> TestContext {
+    tracing_subscriber::fmt::try_init().ok();
+    let node_proc = test_node_process_with(AccountKeyring::Alice).await;
+    let api = node_proc.client().clone().to_runtime_api();
+    TestContext { node_proc, api }
+}
+
+pub fn pair_signer(pair: Pair) -> PairSigner<DefaultConfig, Pair> {
+    PairSigner::new(pair)
+}

testing/integration-tests/src/utils/mod.rs

@@ -0,0 +1,21 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+mod context;
+mod node_proc;
+
+pub use context::*;
+pub use node_proc::TestNodeProcess;

testing/integration-tests/src/utils/node_proc.rs

@@ -0,0 +1,193 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use sp_keyring::AccountKeyring;
+use std::{
+    ffi::{
+        OsStr,
+        OsString,
+    },
+    io::{
+        BufRead,
+        BufReader,
+        Read,
+    },
+    process,
+};
+use subxt::{
+    Client,
+    ClientBuilder,
+    Config,
+};
+
+/// Spawn a local substrate node for testing subxt.
+pub struct TestNodeProcess<R: Config> {
+    proc: process::Child,
+    client: Client<R>,
+    ws_url: String,
+}
+
+impl<R> Drop for TestNodeProcess<R>
+where
+    R: Config,
+{
+    fn drop(&mut self) {
+        let _ = self.kill();
+    }
+}
+
+impl<R> TestNodeProcess<R>
+where
+    R: Config,
+{
+    /// Construct a builder for spawning a test node process.
+    pub fn build<S>(program: S) -> TestNodeProcessBuilder
+    where
+        S: AsRef<OsStr> + Clone,
+    {
+        TestNodeProcessBuilder::new(program)
+    }
+
+    /// Attempt to kill the running substrate process.
+    pub fn kill(&mut self) -> Result<(), String> {
+        tracing::info!("Killing node process {}", self.proc.id());
+        if let Err(err) = self.proc.kill() {
+            let err = format!("Error killing node process {}: {}", self.proc.id(), err);
+            tracing::error!("{}", err);
+            return Err(err)
+        }
+        Ok(())
+    }
+
+    /// Returns the subxt client connected to the running node.
+    pub fn client(&self) -> &Client<R> {
+        &self.client
+    }
+
+    /// Returns the address to which the client is connected.
+    pub fn ws_url(&self) -> &str {
+        &self.ws_url
+    }
+}
+
+/// Construct a test node process.
+pub struct TestNodeProcessBuilder {
+    node_path: OsString,
+    authority: Option<AccountKeyring>,
+}
+
+impl TestNodeProcessBuilder {
+    pub fn new<P>(node_path: P) -> TestNodeProcessBuilder
+    where
+        P: AsRef<OsStr>,
+    {
+        Self {
+            node_path: node_path.as_ref().into(),
+            authority: None,
+        }
+    }
+
+    /// Set the authority dev account for a node in validator mode e.g. --alice.
+    pub fn with_authority(&mut self, account: AccountKeyring) -> &mut Self {
+        self.authority = Some(account);
+        self
+    }
+
+    /// Spawn the substrate node at the given path, and wait for rpc to be initialized.
+    pub async fn spawn<R>(&self) -> Result<TestNodeProcess<R>, String>
+    where
+        R: Config,
+    {
+        let mut cmd = process::Command::new(&self.node_path);
+        cmd.env("RUST_LOG", "info")
+            .arg("--dev")
+            .arg("--tmp")
+            .stdout(process::Stdio::piped())
+            .stderr(process::Stdio::piped())
+            .arg("--port=0")
+            .arg("--rpc-port=0")
+            .arg("--ws-port=0");
+
+        if let Some(authority) = self.authority {
+            let authority = format!("{:?}", authority);
+            let arg = format!("--{}", authority.as_str().to_lowercase());
+            cmd.arg(arg);
+        }
+
+        let mut proc = cmd.spawn().map_err(|e| {
+            format!(
+                "Error spawning substrate node '{}': {}",
+                self.node_path.to_string_lossy(),
+                e
+            )
+        })?;
+
+        // Wait for RPC port to be logged (it's logged to stderr):
+        let stderr = proc.stderr.take().unwrap();
+        let ws_port = find_substrate_port_from_output(stderr);
+        let ws_url = format!("ws://127.0.0.1:{}", ws_port);
+
+        // Connect to the node with a subxt client:
+        let client = ClientBuilder::new().set_url(ws_url.clone()).build().await;
+        match client {
+            Ok(client) => {
+                Ok(TestNodeProcess {
+                    proc,
+                    client,
+                    ws_url,
+                })
+            }
+            Err(err) => {
+                let err = format!("Failed to connect to node rpc at {}: {}", ws_url, err);
+                tracing::error!("{}", err);
+                proc.kill().map_err(|e| {
+                    format!("Error killing substrate process '{}': {}", proc.id(), e)
+                })?;
+                Err(err)
+            }
+        }
+    }
+}
+
+// Consume a stderr reader from a spawned substrate command and
+// locate the port number that is logged out to it.
+fn find_substrate_port_from_output(r: impl Read + Send + 'static) -> u16 {
+    BufReader::new(r)
+        .lines()
+        .find_map(|line| {
+            let line =
+                line.expect("failed to obtain next line from stdout for port discovery");
+
+            // does the line contain our port (we expect this specific output from substrate).
+            let line_end = line
+                .rsplit_once("Listening for new connections on 127.0.0.1:")
+                .or_else(|| {
+                    line.rsplit_once("Running JSON-RPC WS server: addr=127.0.0.1:")
+                })
+                .map(|(_, port_str)| port_str)?;
+
+            // trim non-numeric chars from the end of the port part of the line.
+            let port_str = line_end.trim_end_matches(|b| !('0'..='9').contains(&b));
+
+            // expect to have a number here (the chars after '127.0.0.1:') and parse them into a u16.
+            let port_num = port_str.parse().unwrap_or_else(|_| {
+                panic!("valid port expected for log line, got '{port_str}'")
+            });
+
+            Some(port_num)
+        })
+        .expect("We should find a port before the reader ends")
+}

testing/test-runtime/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "test-runtime"
+version = "0.21.0"
+edition = "2021"
+
+[dependencies]
+subxt = { path = "../../subxt" }
+sp-runtime = "6.0.0"
+codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false, features = ["derive", "full", "bit-vec"] }
+
+[build-dependencies]
+subxt = { path = "../../subxt" }
+sp-core = "6.0.0"
+tokio = { version = "1.8", features = ["macros", "rt-multi-thread"] }
+which = "4.2.2"

testing/test-runtime/README.md

@@ -0,0 +1,10 @@
+# test-runtime
+
+The logic for this crate exists mainly in the `build.rs` file.
+
+At compile time, this crate will:
+- Spin up a local `substrate` binary (set the `SUBSTRATE_NODE_PATH` env var to point to a custom binary, otherwise it'll look for `substrate` on your PATH).
+- Obtain metadata from this node.
+- Export the metadata and a `node_runtime` module which has been annotated using the `subxt` proc macro and is based off the above metadata.
+
+The reason for doing this is that our integration tests (which also spin up a Substrate node) can then use the generated `subxt` types from the exact node being tested against, so that we don't have to worry about metadata getting out of sync with the binary under test.

testing/test-runtime/build.rs

@@ -0,0 +1,171 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use std::{
+    env,
+    fs,
+    net::TcpListener,
+    ops::{
+        Deref,
+        DerefMut,
+    },
+    path::Path,
+    process::Command,
+    thread,
+    time,
+};
+use subxt::rpc::{
+    self,
+    ClientT,
+};
+
+static SUBSTRATE_BIN_ENV_VAR: &str = "SUBSTRATE_NODE_PATH";
+
+#[tokio::main]
+async fn main() {
+    run().await;
+}
+
+async fn run() {
+    // Select substrate binary to run based on env var.
+    let substrate_bin =
+        env::var(SUBSTRATE_BIN_ENV_VAR).unwrap_or_else(|_| "substrate".to_owned());
+
+    // Run binary.
+    let port = next_open_port().expect("Cannot spawn substrate: no available ports");
+    let cmd = Command::new(&substrate_bin)
+        .arg("--dev")
+        .arg("--tmp")
+        .arg(format!("--ws-port={}", port))
+        .spawn();
+    let mut cmd = match cmd {
+        Ok(cmd) => KillOnDrop(cmd),
+        Err(ref e) if e.kind() == std::io::ErrorKind::NotFound => {
+            panic!("A substrate binary should be installed on your path for testing purposes. \
+            See https://github.com/paritytech/subxt/tree/master#integration-testing")
+        }
+        Err(e) => {
+            panic!("Cannot spawn substrate command '{}': {}", substrate_bin, e)
+        }
+    };
+
+    // Download metadata from binary; retry until successful, or a limit is hit.
+    let metadata_bytes: sp_core::Bytes = {
+        const MAX_RETRIES: usize = 6;
+        let mut retries = 0;
+
+        loop {
+            if retries >= MAX_RETRIES {
+                panic!("Cannot connect to substrate node after {} retries", retries);
+            }
+
+            // It might take a while for substrate node that spin up the RPC server.
+            // Thus, the connection might get rejected a few times.
+            let res = match rpc::ws_client(&format!("ws://localhost:{}", port)).await {
+                Ok(c) => c.request("state_getMetadata", None).await,
+                Err(e) => Err(e),
+            };
+
+            match res {
+                Ok(res) => {
+                    let _ = cmd.kill();
+                    break res
+                }
+                _ => {
+                    thread::sleep(time::Duration::from_secs(1 << retries));
+                    retries += 1;
+                }
+            };
+        }
+    };
+
+    // Save metadata to a file:
+    let out_dir = env::var_os("OUT_DIR").unwrap();
+    let metadata_path = Path::new(&out_dir).join("metadata.scale");
+    fs::write(&metadata_path, &metadata_bytes.0).expect("Couldn't write metadata output");
+
+    // Write out our expression to generate the runtime API to a file. Ideally, we'd just write this code
+    // in lib.rs, but we must pass a string literal (and not `concat!(..)`) as an arg to `runtime_metadata_path`,
+    // and so we need to spit it out here and include it verbatim instead.
+    let runtime_api_contents = format!(
+        r#"
+        #[subxt::subxt(
+            runtime_metadata_path = "{}",
+            derive_for_all_types = "Eq, PartialEq"
+        )]
+        pub mod node_runtime {{
+            #[subxt(substitute_type = "sp_arithmetic::per_things::Perbill")]
+            use sp_runtime::Perbill;
+        }}
+    "#,
+        metadata_path
+            .to_str()
+            .expect("Path to metadata should be stringifiable")
+    );
+    let runtime_path = Path::new(&out_dir).join("runtime.rs");
+    fs::write(&runtime_path, runtime_api_contents)
+        .expect("Couldn't write runtime rust output");
+
+    let substrate_path =
+        which::which(substrate_bin).expect("Cannot resolve path to substrate binary");
+
+    // Re-build if the substrate binary we're pointed to changes (mtime):
+    println!(
+        "cargo:rerun-if-changed={}",
+        substrate_path.to_string_lossy()
+    );
+    // Re-build if we point to a different substrate binary:
+    println!("cargo:rerun-if-env-changed={}", SUBSTRATE_BIN_ENV_VAR);
+    // Re-build if this file changes:
+    println!("cargo:rerun-if-changed=build.rs");
+}
+
+/// Returns the next open port, or None if no port found.
+fn next_open_port() -> Option<u16> {
+    match TcpListener::bind(("127.0.0.1", 0)) {
+        Ok(listener) => {
+            if let Ok(address) = listener.local_addr() {
+                Some(address.port())
+            } else {
+                None
+            }
+        }
+        Err(_) => None,
+    }
+}
+
+/// If the substrate process isn't explicitly killed on drop,
+/// it seems that panics that occur while the command is running
+/// will leave it running and block the build step from ever finishing.
+/// Wrapping it in this prevents this from happening.
+struct KillOnDrop(std::process::Child);
+
+impl Deref for KillOnDrop {
+    type Target = std::process::Child;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+impl DerefMut for KillOnDrop {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+impl Drop for KillOnDrop {
+    fn drop(&mut self) {
+        let _ = self.0.kill();
+    }
+}

testing/test-runtime/src/lib.rs

@@ -0,0 +1,22 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+#![allow(clippy::too_many_arguments)]
+
+/// The SCALE encoded metadata obtained from a local run of a substrate node.
+pub static METADATA: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/metadata.scale"));
+
+include!(concat!(env!("OUT_DIR"), "/runtime.rs"));

testing/ui-tests/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "ui-tests"
+version = "0.21.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+
+[dev-dependencies]
+trybuild = "1.0.63"
+scale-info = { version = "2.0.0", features = ["bit-vec"] }
+frame-metadata = "15.0.0"
+codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false, features = ["derive", "full", "bit-vec"] }
+subxt = { path = "../../subxt" }

testing/ui-tests/src/dispatch_errors.rs

@@ -0,0 +1,39 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::utils::{
+    dispatch_error::{
+        ArrayDispatchError,
+        LegacyDispatchError,
+        NamedFieldDispatchError,
+    },
+    generate_metadata_from_pallets_custom_dispatch_error,
+};
+use frame_metadata::RuntimeMetadataPrefixed;
+
+pub fn metadata_array_dispatch_error() -> RuntimeMetadataPrefixed {
+    generate_metadata_from_pallets_custom_dispatch_error::<ArrayDispatchError>(vec![])
+}
+
+pub fn metadata_legacy_dispatch_error() -> RuntimeMetadataPrefixed {
+    generate_metadata_from_pallets_custom_dispatch_error::<LegacyDispatchError>(vec![])
+}
+
+pub fn metadata_named_field_dispatch_error() -> RuntimeMetadataPrefixed {
+    generate_metadata_from_pallets_custom_dispatch_error::<NamedFieldDispatchError>(
+        vec![],
+    )
+}

testing/ui-tests/src/lib.rs

@@ -0,0 +1,51 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+#![cfg(test)]
+
+mod dispatch_errors;
+mod storage;
+mod utils;
+
+use crate::utils::MetadataTestRunner;
+
+// Each of these tests leads to some rust code being compiled and
+// executed to test that compilation is successful (or errors in the
+// way that we'd expect).
+#[test]
+fn ui_tests() {
+    let mut m = MetadataTestRunner::default();
+    let t = trybuild::TestCases::new();
+
+    // Check that storage maps with no keys are handled properly.
+    t.pass(&m.path_to_ui_test_for_metadata(
+        "storage_map_no_keys",
+        storage::metadata_storage_map_no_keys(),
+    ));
+
+    // Test that the codegen can handle the different types of DispatchError.
+    t.pass(&m.path_to_ui_test_for_metadata(
+        "named_field_dispatch_error",
+        dispatch_errors::metadata_named_field_dispatch_error(),
+    ));
+    t.pass(&m.path_to_ui_test_for_metadata(
+        "legacy_dispatch_error",
+        dispatch_errors::metadata_legacy_dispatch_error(),
+    ));
+    t.pass(&m.path_to_ui_test_for_metadata(
+        "array_dispatch_error",
+        dispatch_errors::metadata_array_dispatch_error(),
+    ));
+}

testing/ui-tests/src/storage.rs

@@ -0,0 +1,42 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use frame_metadata::{
+    RuntimeMetadataPrefixed,
+    StorageEntryMetadata,
+    StorageEntryModifier,
+    StorageEntryType,
+};
+use scale_info::meta_type;
+
+use crate::utils::generate_metadata_from_storage_entries;
+
+/// Generate metadata which contains a `Map` storage entry with no hashers/values.
+/// This is a bit of an odd case, but it was raised in https://github.com/paritytech/subxt/issues/552,
+/// and this test will fail before the fix and should pass once the fix is applied.
+pub fn metadata_storage_map_no_keys() -> RuntimeMetadataPrefixed {
+    generate_metadata_from_storage_entries(vec![StorageEntryMetadata {
+        name: "MapWithNoKeys",
+        modifier: StorageEntryModifier::Optional,
+        ty: StorageEntryType::Map {
+            hashers: vec![],
+            key: meta_type::<()>(),
+            value: meta_type::<u32>(),
+        },
+        default: vec![0],
+        docs: vec![],
+    }])
+}

testing/ui-tests/src/utils/dispatch_error.rs

@@ -0,0 +1,120 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use scale_info::{
+    build::{
+        FieldsBuilder,
+        NamedFields,
+        UnnamedFields,
+        Variants,
+    },
+    Path,
+    Type,
+    TypeInfo,
+};
+
+/// See the `ModuleErrorType` in `subxt_codegen` for more info on the different DispatchError
+/// types that we've encountered. We need the path to match `sp_runtime::DispatchError`, otherwise
+/// we could just implement roughly the correct types and derive TypeInfo on them.
+
+/// This type has TypeInfo compatible with the `NamedField` version of the DispatchError.
+/// This is the oldest version that subxt supports:
+/// `DispatchError::Module { index: u8, error: u8 }`
+pub enum NamedFieldDispatchError {}
+impl TypeInfo for NamedFieldDispatchError {
+    type Identity = Self;
+    fn type_info() -> Type {
+        Type::builder()
+            .path(Path::new("DispatchError", "sp_runtime"))
+            .variant(Variants::new().variant("Module", |builder| {
+                builder
+                    .fields(
+                        FieldsBuilder::<NamedFields>::default()
+                            .field(|b| b.name("error").ty::<u8>())
+                            .field(|b| b.name("index").ty::<u8>()),
+                    )
+                    .index(0)
+            }))
+    }
+}
+
+/// This type has TypeInfo compatible with the `LegacyError` version of the DispatchError.
+/// This is the version wasn't around for long:
+/// `DispatchError::Module ( sp_runtime::ModuleError { index: u8, error: u8 } )`
+pub enum LegacyDispatchError {}
+impl TypeInfo for LegacyDispatchError {
+    type Identity = Self;
+    fn type_info() -> Type {
+        struct ModuleError;
+        impl TypeInfo for ModuleError {
+            type Identity = Self;
+            fn type_info() -> Type {
+                Type::builder()
+                    .path(Path::new("ModuleError", "sp_runtime"))
+                    .composite(
+                        FieldsBuilder::<NamedFields>::default()
+                            .field(|b| b.name("index").ty::<u8>())
+                            .field(|b| b.name("error").ty::<u8>()),
+                    )
+            }
+        }
+
+        Type::builder()
+            .path(Path::new("DispatchError", "sp_runtime"))
+            .variant(Variants::new().variant("Module", |builder| {
+                builder
+                    .fields(
+                        FieldsBuilder::<UnnamedFields>::default()
+                            .field(|b| b.ty::<ModuleError>()),
+                    )
+                    .index(0)
+            }))
+    }
+}
+
+/// This type has TypeInfo compatible with the `ArrayError` version of the DispatchError.
+/// This is the current version:
+/// `DispatchError::Module ( sp_runtime::ModuleError { index: u8, error: [u8; 4] } )`
+pub enum ArrayDispatchError {}
+impl TypeInfo for ArrayDispatchError {
+    type Identity = Self;
+    fn type_info() -> Type {
+        struct ModuleError;
+        impl TypeInfo for ModuleError {
+            type Identity = Self;
+            fn type_info() -> Type {
+                Type::builder()
+                    .path(Path::new("ModuleError", "sp_runtime"))
+                    .composite(
+                        FieldsBuilder::<NamedFields>::default()
+                            .field(|b| b.name("index").ty::<u8>())
+                            .field(|b| b.name("error").ty::<[u8; 4]>()),
+                    )
+            }
+        }
+
+        Type::builder()
+            .path(Path::new("DispatchError", "sp_runtime"))
+            .variant(Variants::new().variant("Module", |builder| {
+                builder
+                    .fields(
+                        FieldsBuilder::<UnnamedFields>::default()
+                            .field(|b| b.ty::<ModuleError>()),
+                    )
+                    .index(0)
+            }))
+    }
+}

testing/ui-tests/src/utils/metadata_test_runner.rs

@@ -0,0 +1,85 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use codec::Encode;
+use frame_metadata::RuntimeMetadataPrefixed;
+
+static TEST_DIR_PREFIX: &str = "subxt_generated_ui_tests_";
+
+#[derive(Default)]
+pub struct MetadataTestRunner {
+    index: usize,
+}
+
+impl MetadataTestRunner {
+    pub fn path_to_ui_test_for_metadata(
+        &mut self,
+        name: impl AsRef<str>,
+        metadata: RuntimeMetadataPrefixed,
+    ) -> String {
+        let test_name = name.as_ref();
+
+        // increment test index to avoid overlaps.
+        let index = self.index;
+        self.index += 1;
+
+        let mut tmp_dir = std::env::temp_dir();
+        tmp_dir.push(format!("{TEST_DIR_PREFIX}{index}"));
+
+        let tmp_metadata_path = {
+            let mut t = tmp_dir.clone();
+            t.push("metadata.scale");
+            t.to_string_lossy().into_owned()
+        };
+        let tmp_rust_path = {
+            let mut t = tmp_dir.clone();
+            t.push(format!("{test_name}.rs"));
+            t.to_string_lossy().into_owned()
+        };
+
+        let encoded_metadata = metadata.encode();
+        let rust_file = format!(
+            r#"
+            use subxt;
+
+            #[subxt::subxt(runtime_metadata_path = "{tmp_metadata_path}")]
+            pub mod polkadot {{}}
+
+            fn main() {{}}
+        "#
+        );
+
+        std::fs::create_dir_all(&tmp_dir).expect("could not create tmp ui test dir");
+        // Write metadata to tmp folder:
+        std::fs::write(&tmp_metadata_path, &encoded_metadata).unwrap();
+        // Write test file to tmp folder (it'll be moved by trybuild):
+        std::fs::write(&tmp_rust_path, &rust_file).unwrap();
+
+        tmp_rust_path
+    }
+}
+
+// `trybuild` runs all tests once it's dropped. So, we defer all cleanup until we
+// are dropped too, to make sure that cleanup happens after tests are ran.
+impl Drop for MetadataTestRunner {
+    fn drop(&mut self) {
+        for i in 0..self.index {
+            let mut tmp_dir = std::env::temp_dir();
+            tmp_dir.push(format!("{TEST_DIR_PREFIX}{i}"));
+            std::fs::remove_dir_all(tmp_dir).expect("cannot cleanup temp files");
+        }
+    }
+}

testing/ui-tests/src/utils/mod.rs

@@ -0,0 +1,104 @@
+// Copyright 2019-2022 Parity Technologies (UK) Ltd.
+// This file is part of subxt.
+//
+// subxt is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// subxt is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+pub mod dispatch_error;
+mod metadata_test_runner;
+
+use frame_metadata::{
+    v14::RuntimeMetadataV14,
+    ExtrinsicMetadata,
+    PalletMetadata,
+    PalletStorageMetadata,
+    RuntimeMetadataPrefixed,
+    StorageEntryMetadata,
+};
+use scale_info::{
+    meta_type,
+    IntoPortable,
+    TypeInfo,
+};
+
+pub use metadata_test_runner::MetadataTestRunner;
+
+/// Given some pallet metadata, generate a [`RuntimeMetadataPrefixed`] struct.
+/// We default to a useless extrinsic type, and register a fake `DispatchError`
+/// type matching the generic type param provided.
+pub fn generate_metadata_from_pallets_custom_dispatch_error<
+    DispatchError: TypeInfo + 'static,
+>(
+    pallets: Vec<PalletMetadata>,
+) -> RuntimeMetadataPrefixed {
+    // We don't care about the extrinsic type.
+    let extrinsic = ExtrinsicMetadata {
+        ty: meta_type::<()>(),
+        version: 0,
+        signed_extensions: vec![],
+    };
+
+    // Construct metadata manually from our types (See `RuntimeMetadataV14::new()`).
+    // Add any extra types we need to the registry.
+    let mut registry = scale_info::Registry::new();
+    let pallets = registry.map_into_portable(pallets);
+    let extrinsic = extrinsic.into_portable(&mut registry);
+    let ty = registry.register_type(&meta_type::<()>());
+
+    // Metadata needs to contain this DispatchError, since codegen looks for it.
+    registry.register_type(&meta_type::<DispatchError>());
+
+    let metadata = RuntimeMetadataV14 {
+        types: registry.into(),
+        pallets,
+        extrinsic,
+        ty,
+    };
+
+    RuntimeMetadataPrefixed::from(metadata)
+}
+
+/// Given some pallet metadata, generate a [`RuntimeMetadataPrefixed`] struct.
+/// We default to a useless extrinsic type, and register a fake `DispatchError`
+/// type so that codegen is happy with the metadata generated.
+pub fn generate_metadata_from_pallets(
+    pallets: Vec<PalletMetadata>,
+) -> RuntimeMetadataPrefixed {
+    generate_metadata_from_pallets_custom_dispatch_error::<
+        dispatch_error::ArrayDispatchError,
+    >(pallets)
+}
+
+/// Given some storage entries, generate a [`RuntimeMetadataPrefixed`] struct.
+/// We default to a useless extrinsic type, mock a pallet out, and register a
+/// fake `DispatchError` type so that codegen is happy with the metadata generated.
+pub fn generate_metadata_from_storage_entries(
+    storage_entries: Vec<StorageEntryMetadata>,
+) -> RuntimeMetadataPrefixed {
+    let storage = PalletStorageMetadata {
+        prefix: "System",
+        entries: storage_entries,
+    };
+
+    let pallet = PalletMetadata {
+        index: 0,
+        name: "System",
+        storage: Some(storage),
+        constants: vec![],
+        calls: None,
+        event: None,
+        error: None,
+    };
+
+    generate_metadata_from_pallets(vec![pallet])
+}