offchain-worker: Do not intialize the entire System again

substrate/frame/executive/src/lib.rs

@@ -953,7 +953,11 @@ where
 		// OffchainWorker RuntimeApi should skip initialization.
 		let digests = header.digest().clone();
 
-		<frame_system::Pallet<System>>::initialize(header.number(), header.parent_hash(), &digests);
+		// Let's deposit all the logs we are not yet aware of. These are the logs set by the `node`.
+		let existing_digest = frame_system::Pallet::<System>::digest();
+		for digest in digests.logs().iter().filter(|d| !existing_digest.logs.contains(d)) {
+			frame_system::Pallet::<System>::deposit_log(digest.clone());
+		}
 
 		// Frame system only inserts the parent hash into the block hashes as normally we don't know
 		// the hash for the header before. However, here we are aware of the hash and we can add it

substrate/frame/executive/src/tests.rs

@@ -1113,7 +1113,14 @@ fn all_weights_are_recorded_correctly() {
 fn offchain_worker_works_as_expected() {
 	new_test_ext(1).execute_with(|| {
 		let parent_hash = sp_core::H256::from([69u8; 32]);
+
+		// Emulate block production before running the offchain worker.
+		System::initialize(&1, &parent_hash, &Digest::default());
+		System::finalize();
+
 		let mut digest = Digest::default();
+		// As `Seal` is added by the node after the block was build, it was not part of
+		// `System::initialize` above.
 		digest.push(DigestItem::Seal([1, 2, 3, 4], vec![5, 6, 7, 8]));
 
 		let header = Header::new(1, H256::default(), H256::default(), parent_hash, digest.clone());

substrate/test-utils/runtime/src/lib.rs

@@ -742,6 +742,7 @@ impl_runtime_apis! {
 				}.into(),
 			);
 			sp_io::offchain::submit_transaction(ext.encode()).unwrap();
+			Executive::offchain_worker(header);
 		}
 	}