Generate Unit Tests for Benchmarks (#5527)

* Update to latest staking

* generate tests for benchmarking

* add tests, fix warnings

* starting on democracy

* impl_benchmark_tests

* Way more readable

* add test feature flag (does this work?)

* Fix `successful_origin` impl

* democracry benchmark tests

* Fix example benchmarks, add tests

* identity benchmark tests

* Update im-online benchmark tests

* try to add session benchmarking tests (problem with mock)

* staking and timestamp

* add test for treasury, issue with dynamic contains

* utility

* Vesting

* test instead of check

* hide until we figure out what is wrong

* add docs

* close code

* Create custom mock for session-pallet-benchmarking

* Use refcell pattern

* make un-pub

* test-linux-stable includes `runtime-benchmarks` feature

* Revert "test-linux-stable includes `runtime-benchmarks` feature"

This reverts commit a2dab38abd18ac3eb8a6220e4a00e687740bd38c.

* run tests in `--release`

* undo balance change

* build wasm

substrate/frame/system/src/lib.rs

@@ -620,9 +620,12 @@ impl<
 
 	#[cfg(feature = "runtime-benchmarks")]
 	fn successful_origin() -> O {
-		let caller: AccountId = Default::default();
-		// Who::add(&caller);
-		O::from(RawOrigin::Signed(caller))
+		let members = Who::sorted_members();
+		let first_member = match members.get(0) {
+			Some(account) => account.clone(),
+			None => Default::default(),
+		};
+		O::from(RawOrigin::Signed(first_member.clone()))
 	}
 }