Followup test for checking propagated documentation (#514)

* codegen: Composite fields docs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Propagate docs for Event type

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Propagate docs for calls module

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Update polkadot.rs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen: Propagate documentation for `TypeDefGenKind::Enum` kind

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Update polkadot.rs

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen/tests: Recursively obtain raw metadata documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen/tests: Generate runtime interface from node metadata

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen/tests: Obtain documentation from generated runtime API

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen/tests: Match raw documentation with the generated one

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Revert not longer needed "codegen: Composite fields docs"

This reverts commit 5460bbafc6262ac4f53e11d4ef11e44e1ce8296f.

* codegen/tests: Improve test regex documentation

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Add integration-tests feature flag

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Guard integration tests under feature flag

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* test-runtime: Place build.rs under feature flag

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Pass `integration-tests` feature to `test-runtime`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* CI: Use `integration-tests` feature to run all tests

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Rely on `#[cfg(feature = "integration-tests")]` for integration

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt/metadata: Manually construct test metadata

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* artifacts: Move scale binary blob to dedicated folder

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Update path to metadata blob

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* metadata: Rely on artifact metadata blob for benches

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* metadata: Remove `test-runtime` dependency

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* examples: Modify runtime path for `custom_type_derives`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Remove tests folder

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* test-runtime: Remove `integration-tests` feature flag

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* integration-tests: Add an integration test crate for subxt

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Remove `test-runtime` dependency

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* subxt: Add comment for feature flags

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* integration-tests: Trim dependencies

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* integration-tests: Move dependencies under dev

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Revert "CI: Use `integration-tests` feature to run all tests"

This reverts commit 8e5f38ba8c633ac40420fadf58700ac402f762d4.

* codegen: Move documentation test to integration crate

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* codegen_documentation: Add license + fmt

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update `polkadot.rs`

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Move test under `testing` folder

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

* Update testing/integration-tests/src/codegen/codegen_documentation.rs

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

Co-authored-by: Tarik Gul <47201679+TarikGul@users.noreply.github.com>

codegen/src/api/calls.rs

@@ -154,7 +154,11 @@ pub fn generate_calls(
         })
         .unzip();
 
+    let call_ty = type_gen.resolve_type(call.ty.id());
+    let docs = call_ty.docs();
+
     quote! {
+        #( #[doc = #docs ] )*
         pub mod calls {
             use super::root_mod;
             use super::#types_mod_ident;

codegen/src/api/events.rs

@@ -81,8 +81,11 @@ pub fn generate_events(
         }
     });
     let event_type = type_gen.resolve_type_path(event.ty.id(), &[]);
+    let event_ty = type_gen.resolve_type(event.ty.id());
+    let docs = event_ty.docs();
 
     quote! {
+        #( #[doc = #docs ] )*
         pub type Event = #event_type;
         pub mod events {
             use super::#types_mod_ident;

codegen/src/types/type_def.rs

@@ -46,6 +46,8 @@ pub struct TypeDefGen {
     derives: Derives,
     /// The kind of type to be generated.
     ty_kind: TypeDefGenKind,
+    /// Type documentation.
+    ty_docs: TokenStream,
 }
 
 impl TypeDefGen {
@@ -119,10 +121,14 @@ impl TypeDefGen {
             _ => TypeDefGenKind::BuiltIn,
         };
 
+        let docs = ty.docs();
+        let ty_docs = quote! { #( #[doc = #docs ] )* };
+
         Self {
             type_params,
             derives,
             ty_kind,
+            ty_docs,
         }
     }
 }
@@ -152,8 +158,10 @@ impl quote::ToTokens for TypeDefGen {
                 let enum_ident = format_ident!("{}", type_name);
                 let type_params = &self.type_params;
                 let derives = &self.derives;
+                let docs = &self.ty_docs;
                 let ty_toks = quote! {
                     #derives
+                    #docs
                     pub enum #enum_ident #type_params {
                         #( #variants, )*
                     }

integration-tests/Cargo.toml

@@ -1,33 +0,0 @@
-[package]
-name = "subxt-integration"
-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"

integration-tests/src/lib.rs

@@ -1,38 +0,0 @@
-// 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::*;

integration-tests/src/metadata/validation.rs

@@ -1,340 +0,0 @@
-// 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/Cargo.toml

@@ -20,11 +20,14 @@ codec = { package = "parity-scale-codec", version = "3.0.0", default-features =
 frame-metadata = "15.0.0"
 futures = "0.3.13"
 hex = "0.4.3"
+regex = "1.5.0"
 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"
+syn = "1.0.0"
 subxt = { version = "0.21.0", path = "../../subxt" }
+subxt-codegen = { version = "0.21.0", path = "../../codegen" }
 test-runtime = { path = "../test-runtime" }
 tokio = { version = "1.8", features = ["macros", "time"] }
 tracing = "0.1.34"

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

@@ -0,0 +1,119 @@
+// 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 regex::Regex;
+use subxt_codegen::{
+    DerivesRegistry,
+    RuntimeGenerator,
+};
+
+fn metadata_docs() -> Vec<String> {
+    // Load the runtime metadata downloaded from a node via `test-runtime`.
+    let bytes = test_runtime::METADATA;
+    let meta: frame_metadata::RuntimeMetadataPrefixed =
+        codec::Decode::decode(&mut &*bytes).expect("Cannot decode scale metadata");
+    let metadata = match meta.1 {
+        frame_metadata::RuntimeMetadata::V14(v14) => v14,
+        _ => panic!("Unsupported metadata version {:?}", meta.1),
+    };
+
+    // Inspect the metadata types and collect the documentation.
+    let mut docs = Vec::new();
+    for ty in metadata.types.types() {
+        docs.extend_from_slice(ty.ty().docs());
+    }
+
+    for pallet in metadata.pallets {
+        if let Some(storage) = pallet.storage {
+            for entry in storage.entries {
+                docs.extend(entry.docs);
+            }
+        }
+        // Note: Calls, Events and Errors are deduced directly to
+        // PortableTypes which are handled above.
+        for constant in pallet.constants {
+            docs.extend(constant.docs);
+        }
+    }
+    // Note: Extrinsics do not have associated documentation, but is implied by
+    // associated Type.
+
+    docs
+}
+
+fn generate_runtime_interface() -> String {
+    // Load the runtime metadata downloaded from a node via `test-runtime`.
+    let bytes = test_runtime::METADATA;
+    let metadata: frame_metadata::RuntimeMetadataPrefixed =
+        codec::Decode::decode(&mut &*bytes).expect("Cannot decode scale metadata");
+
+    // Generate a runtime interface from the provided metadata.
+    let generator = RuntimeGenerator::new(metadata);
+    let item_mod = syn::parse_quote!(
+        pub mod api {}
+    );
+    let derives = DerivesRegistry::default();
+    generator.generate_runtime(item_mod, derives).to_string()
+}
+
+fn interface_docs() -> Vec<String> {
+    // Generate the runtime interface from the node's metadata.
+    // Note: the API is generated on a single line.
+    let runtime_api = generate_runtime_interface();
+
+    // Documentation lines have the following format:
+    //    # [ doc = "Upward message is invalid XCM."]
+    // Given the API is generated on a single line, the regex matching
+    // must be lazy hence the `?` in the matched group `(.*?)`.
+    //
+    // The greedy `non-?` matching would lead to one single match
+    // from the beginning of the first documentation tag, containing everything up to
+    // the last documentation tag
+    // `# [ doc = "msg"] # [ doc = "msg2"] ... api ... # [ doc = "msgN" ]`
+    //
+    // The `(.*?)` stands for match any character zero or more times lazily.
+    let re = Regex::new(r#"\# \[doc = "(.*?)"\]"#).unwrap();
+    re.captures_iter(&runtime_api)
+        .filter_map(|capture| {
+            // Get the matched group (ie index 1).
+            capture.get(1).as_ref().map(|doc| {
+                // Generated documentation will escape special characters.
+                // Replace escaped characters with unescaped variants for
+                // exact matching on the raw metadata documentation.
+                doc.as_str()
+                    .replace("\\n", "\n")
+                    .replace("\\t", "\t")
+                    .replace("\\\"", "\"")
+            })
+        })
+        .collect()
+}
+
+#[test]
+fn check_documentation() {
+    // Inspect metadata recursively and obtain all associated documentation.
+    let raw_docs = metadata_docs();
+    // Obtain documentation from the generated API.
+    let runtime_docs = interface_docs();
+
+    for raw in raw_docs.iter() {
+        assert!(
+            runtime_docs.contains(raw),
+            "Documentation not present in runtime API: {}",
+            raw
+        );
+    }
+}

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

@@ -24,3 +24,5 @@
 #[rustfmt::skip]
 #[allow(clippy::all)]
 mod polkadot;
+
+mod codegen_documentation;