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/session/src/mock.rs

@@ -150,6 +150,16 @@ pub fn reset_before_session_end_called() {
 	BEFORE_SESSION_END_CALLED.with(|b| *b.borrow_mut() = false);
 }
 
+pub fn new_test_ext() -> sp_io::TestExternalities {
+	let mut t = frame_system::GenesisConfig::default().build_storage::<Test>().unwrap();
+	GenesisConfig::<Test> {
+		keys: NEXT_VALIDATORS.with(|l|
+			l.borrow().iter().cloned().map(|i| (i, i, UintAuthorityId(i).into())).collect()
+		),
+	}.assimilate_storage(&mut t).unwrap();
+	sp_io::TestExternalities::new(t)
+}
+
 #[derive(Clone, Eq, PartialEq)]
 pub struct Test;