Add proper commit_all to TestExternalities (#7808)

* Add proper `commit_all` to `TestExternalities`

This pr adds a propoer `commit_all` function to `TestExternalities` to
commit all changes from the overlay to the internal backend. Besides
that it fixes some bugs with handling empty dbs when calculating a delta
storage root. It also changes the way data is added to the in memory
backend.

* Update primitives/state-machine/src/testing.rs

Co-authored-by: cheme <emericchevalier.pro@gmail.com>

* Don't allow self proxies (#7803)

* Allow council to slash treasury tip (#7753)

* wk2051 | D4 |Allow council to slash treasury tip | p1

* Update frame/tips/src/lib.rs

Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>

* wk2051 | D5 |Allow council to slash treasury tip | p2

* wk2051 | D5 |Allow council to slash treasury tip | p3

* wk2051 | D5 |Allow council to slash treasury tip | p4

* wk2051 | D5 |Allow council to slash treasury tip | p5

* random change

* cargo run --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_tips --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/tips/src/weights.rs --template=./.maintain/frame-weight-template.hbs

* fix typo

* Update frame/tips/src/lib.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update frame/tips/src/lib.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update frame/tips/src/lib.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update frame/tips/src/lib.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Update frame/tips/src/tests.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* wk2052 | D1 | Allow council to slash treasury tip | p6

Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>
Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: Parity Benchmarking Bot <admin@parity.io>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Review feedback

* Review feedback

* Update docs

* More docs

* Make it private

* Use `None`

* Use apply transaction

* Update primitives/state-machine/src/testing.rs

Co-authored-by: cheme <emericchevalier.pro@gmail.com>
Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>
Co-authored-by: RK <r.raajey@gmail.com>
Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>
Co-authored-by: Parity Benchmarking Bot <admin@parity.io>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>

substrate/primitives/state-machine/src/testing.rs

@@ -153,8 +153,11 @@ impl<H: Hasher, N: ChangesTrieBlockNumber> TestExternalities<H, N>
 		&mut self.changes_trie_storage
 	}
 
-	/// Return a new backend with all pending value.
-	pub fn commit_all(&self) -> InMemoryBackend<H> {
+	/// Return a new backend with all pending changes.
+	///
+	/// In contrast to [`commit_all`](Self::commit_all) this will not panic if there are open
+	/// transactions.
+	fn as_backend(&self) -> InMemoryBackend<H> {
 		let top: Vec<_> = self.overlay.changes()
 			.map(|(k, v)| (k.clone(), v.value().cloned()))
 			.collect();
@@ -172,6 +175,23 @@ impl<H: Hasher, N: ChangesTrieBlockNumber> TestExternalities<H, N>
 		self.backend.update(transaction)
 	}
 
+	/// Commit all pending changes to the underlying backend.
+	///
+	/// # Panic
+	///
+	/// This will panic if there are still open transactions.
+	pub fn commit_all(&mut self) -> Result<(), String> {
+		let changes = self.overlay.drain_storage_changes::<_, _, N>(
+			&self.backend,
+			None,
+			Default::default(),
+			&mut Default::default(),
+		)?;
+
+		self.backend.apply_transaction(changes.transaction_storage_root, changes.transaction);
+		Ok(())
+	}
+
 	/// Execute the given closure while `self` is set as externalities.
 	///
 	/// Returns the result of the given closure.
@@ -209,7 +229,7 @@ impl<H: Hasher, N: ChangesTrieBlockNumber> PartialEq for TestExternalities<H, N>
 	/// This doesn't test if they are in the same state, only if they contains the
 	/// same data at this state
 	fn eq(&self, other: &TestExternalities<H, N>) -> bool {
-		self.commit_all().eq(&other.commit_all())
+		self.as_backend().eq(&other.as_backend())
 	}
 }
 
@@ -258,7 +278,7 @@ impl<H, N> sp_externalities::ExtensionStore for TestExternalities<H, N> where
 #[cfg(test)]
 mod tests {
 	use super::*;
-	use sp_core::{H256, traits::Externalities};
+	use sp_core::{H256, traits::Externalities, storage::ChildInfo};
 	use sp_runtime::traits::BlakeTwo256;
 	use hex_literal::hex;
 
@@ -289,4 +309,45 @@ mod tests {
 		fn assert_send<T: Send>() {}
 		assert_send::<TestExternalities::<BlakeTwo256, u64>>();
 	}
+
+	#[test]
+	fn commit_all_and_kill_child_storage() {
+		let mut ext = TestExternalities::<BlakeTwo256, u64>::default();
+		let child_info = ChildInfo::new_default(&b"test_child"[..]);
+
+		{
+			let mut ext = ext.ext();
+			ext.place_child_storage(&child_info, b"doe".to_vec(), Some(b"reindeer".to_vec()));
+			ext.place_child_storage(&child_info, b"dog".to_vec(), Some(b"puppy".to_vec()));
+			ext.place_child_storage(&child_info, b"dog2".to_vec(), Some(b"puppy2".to_vec()));
+		}
+
+		ext.commit_all().unwrap();
+
+		{
+			let mut ext = ext.ext();
+
+			assert!(!ext.kill_child_storage(&child_info, Some(2)), "Should not delete all keys");
+
+			assert!(ext.child_storage(&child_info, &b"doe"[..]).is_none());
+			assert!(ext.child_storage(&child_info, &b"dog"[..]).is_none());
+			assert!(ext.child_storage(&child_info, &b"dog2"[..]).is_some());
+		}
+	}
+
+	#[test]
+	fn as_backend_generates_same_backend_as_commit_all() {
+		let mut ext = TestExternalities::<BlakeTwo256, u64>::default();
+		{
+			let mut ext = ext.ext();
+			ext.set_storage(b"doe".to_vec(), b"reindeer".to_vec());
+			ext.set_storage(b"dog".to_vec(), b"puppy".to_vec());
+			ext.set_storage(b"dogglesworth".to_vec(), b"cat".to_vec());
+		}
+
+		let backend = ext.as_backend();
+
+		ext.commit_all().unwrap();
+		assert!(ext.backend.eq(&backend), "Both backend should be equal.");
+	}
 }