Make TestOffchainExt panic on unknown requests (#3710)

* Make `TestOffchainExt` panic on unknown requests

* Fix test

substrate/core/executor/src/wasm_executor.rs

@@ -1842,7 +1842,7 @@ mod tests {
 				body: vec![1, 2, 3, 4],
 				headers: vec![("X-Auth".to_owned(), "test".to_owned())],
 				sent: true,
-				response: vec![1, 2, 3],
+				response: Some(vec![1, 2, 3]),
 				response_headers: vec![("X-Auth".to_owned(), "hello".to_owned())],
 				..Default::default()
 			},

substrate/core/offchain/src/testing.rs

@@ -48,7 +48,7 @@ pub struct PendingRequest {
 	/// Has the request been sent already.
 	pub sent: bool,
 	/// Response body
-	pub response: Vec<u8>,
+	pub response: Option<Vec<u8>>,
 	/// Number of bytes already read from the response body.
 	pub read: usize,
 	/// Response headers
@@ -89,7 +89,7 @@ impl State {
 					*req,
 					expected,
 				);
-				req.response = response.into();
+				req.response = Some(response.into());
 				req.response_headers = response_headers.into_iter().collect();
 			}
 		}
@@ -97,7 +97,7 @@ impl State {
 
 	fn fulfill_expected(&mut self, id: u16) {
 		if let Some(mut req) = self.expected_requests.remove(&RequestId(id)) {
-			let response = std::mem::replace(&mut req.response, vec![]);
+			let response = req.response.take().expect("Response checked while added.");
 			let headers = std::mem::replace(&mut req.response_headers, vec![]);
 			self.fulfill_pending_request(id, req, response, headers);
 		}
@@ -110,6 +110,9 @@ impl State {
 	/// Expected request has to be fulfilled before this struct is dropped,
 	/// the `response` and `response_headers` fields will be used to return results to the callers.
 	pub fn expect_request(&mut self, id: u16, expected: PendingRequest) {
+		if expected.response.is_none() {
+			panic!("Expected request needs to have a response.");
+		}
 		self.expected_requests.insert(RequestId(id), expected);
 	}
 }
@@ -254,7 +257,8 @@ impl offchain::Externalities for TestOffchainExt {
 		let state = self.0.read();
 
 		ids.iter().map(|id| match state.requests.get(id) {
-			Some(req) if req.response.is_empty() => RequestStatus::DeadlineReached,
+			Some(req) if req.response.is_none() =>
+				panic!("No `response` provided for request with id: {:?}", id),
 			None => RequestStatus::Invalid,
 			_ => RequestStatus::Finished(200),
 		}).collect()
@@ -281,13 +285,17 @@ impl offchain::Externalities for TestOffchainExt {
 	) -> Result<usize, HttpError> {
 		let mut state = self.0.write();
 		if let Some(req) = state.requests.get_mut(&request_id) {
-			if req.read >= req.response.len() {
+			let response = req.response
+				.as_mut()
+				.expect(&format!("No response provided for request: {:?}", request_id));
+
+			if req.read >= response.len() {
 				// Remove the pending request as per spec.
 				state.requests.remove(&request_id);
 				Ok(0)
 			} else {
-				let read = std::cmp::min(buffer.len(), req.response[req.read..].len());
-				buffer[0..read].copy_from_slice(&req.response[req.read..read]);
+				let read = std::cmp::min(buffer.len(), response[req.read..].len());
+				buffer[0..read].copy_from_slice(&response[req.read..read]);
 				req.read += read;
 				Ok(read)
 			}