Impl integrity test for runtime (#6356)

* impl integrity test for runtime

* Update frame/support/src/traits.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update frame/support/procedural/src/construct_runtime/mod.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* use thread local

* update doc

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
Co-authored-by: Gavin Wood <gavin@parity.io>

substrate/frame/support/test/tests/construct_runtime.rs

@@ -15,16 +15,24 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//! General tests for construct_runtime macro, test for:
+//! * error declareed with decl_error works
+//! * integrity test is generated
+
 #![recursion_limit="128"]
 
 use sp_runtime::{generic, traits::{BlakeTwo256, Block as _, Verify}, DispatchError};
 use sp_core::{H256, sr25519};
-
+use sp_std::cell::RefCell;
 
 mod system;
 
 pub trait Currency {}
 
+thread_local! {
+    pub static INTEGRITY_TEST_EXEC: RefCell<u32> = RefCell::new(0);
+}
+
 mod module1 {
 	use super::*;
 
@@ -65,6 +73,10 @@ mod module2 {
 			pub fn fail(_origin) -> frame_support::dispatch::DispatchResult {
 				Err(Error::<T>::Something.into())
 			}
+
+			fn integrity_test() {
+				INTEGRITY_TEST_EXEC.with(|i| *i.borrow_mut() += 1);
+			}
 		}
 	}
 
@@ -139,3 +151,9 @@ fn check_module2_error_type() {
 		Err(DispatchError::Module { index: 2, error: 0, message: Some("Something") }),
 	);
 }
+
+#[test]
+fn integrity_test_works() {
+	__construct_runtime_integrity_test::runtime_integrity_tests();
+	assert_eq!(INTEGRITY_TEST_EXEC.with(|i| *i.borrow()), 1);
+}