Improve testing and error handling

src/api/rpc_api/author.rs

@@ -289,6 +289,9 @@ where
 		&self,
 		mut report: ExtrinsicReport<Self::Hash>,
 	) -> Result<ExtrinsicReport<Self::Hash>> {
+		if report.events.is_some() {
+			return Err(Error::Other("Report already contains events".into()))
+		}
 		let block_hash = report.block_hash.ok_or(Error::BlockHashNotFound)?;
 		let extrinsic_events =
 			self.fetch_events_for_extrinsic(block_hash, report.extrinsic_hash).await?;

testing/async/examples/author_tests.rs

@@ -174,6 +174,13 @@ async fn test_submit_and_watch_extrinsic_until_in_block_without_events(
 	println!("Extrinsic got successfully included in Block!");
 	assert!(report.block_hash.is_some());
 	assert!(report.events.is_none());
+
+	// Now we fetch the events separately
+	let report = api.populate_events(report).await.unwrap();
+	assert!(report.events.is_some());
+
+	// Can populate events only once
+	assert!(api.populate_events(report).await.is_err());
 }
 
 fn assert_associated_events_match_expected(events: Vec<RawEventDetails<Hash>>) {