Metadata V16: Implement support for Pallet View Functions (#1981)

* Support Pallet View Functions in Subxt

* fmt

* clippy

* Move a little view function logic to subxt_core

* clippy

* Add back check that prob isnt needed

* avoid vec macro in core

* Add view funciton test and apply various fixes to get it working

* Add test for dynamic view fn call and fix issues

* clippy

* fix test-runtime

* fmt

* remove export

* avoid vec for nostd core

* use const instead of fn for view fn call name

* Update to support latest unstable metadata

* Update metadata stripping tests for new v16 version

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

@@ -7,6 +7,7 @@ mod client;
 mod codegen;
 mod frame;
 mod metadata_validation;
+mod pallet_view_functions;
 mod runtime_api;
 mod storage;
 mod transactions;

testing/integration-tests/src/full_client/pallet_view_functions.rs

@@ -0,0 +1,60 @@
+use crate::{subxt_test, test_context};
+use test_runtime::node_runtime_unstable;
+
+#[subxt_test]
+async fn call_view_function() -> Result<(), subxt::Error> {
+    let ctx = test_context().await;
+    let api = ctx.client();
+
+    use node_runtime_unstable::proxy::view_functions::check_permissions::{Call, ProxyType};
+
+    // This is one of only two view functions that currently exists at the time of writing.
+    let call = Call::System(node_runtime_unstable::system::Call::remark {
+        remark: b"hi".to_vec(),
+    });
+    let proxy_type = ProxyType::Any;
+    let view_function_call = node_runtime_unstable::view_functions()
+        .proxy()
+        .check_permissions(call, proxy_type);
+
+    // Submit the call and get back a result.
+    let _is_call_allowed = api
+        .view_functions()
+        .at_latest()
+        .await?
+        .call(view_function_call)
+        .await?;
+
+    Ok(())
+}
+
+#[subxt_test]
+async fn call_view_function_dynamically() -> Result<(), subxt::Error> {
+    let ctx = test_context().await;
+    let api = ctx.client();
+    let metadata = api.metadata();
+
+    let query_id = metadata
+        .pallet_by_name("Proxy")
+        .unwrap()
+        .view_function_by_name("check_permissions")
+        .unwrap()
+        .query_id();
+
+    use scale_value::value;
+
+    let view_function_call = subxt::dynamic::view_function_call(
+        *query_id,
+        vec![value!(System(remark(b"hi".to_vec()))), value!(Any())],
+    );
+
+    // Submit the call and get back a result.
+    let _is_call_allowed = api
+        .view_functions()
+        .at_latest()
+        .await?
+        .call(view_function_call)
+        .await?;
+
+    Ok(())
+}