Handle subprocess crashes during testing

packages/flutter_tools/lib/src/test/loader.dart

@@ -82,42 +82,59 @@ void main() {
 }
 ''');
 
+  Completer completer = new Completer();
+
   Process process = await _startProcess(listenerFile.path,
       packageRoot: p.absolute(config.packageRoot));
 
-  JSONSocket socket = new JSONSocket(await info.socket);
-
-  await tempDir.delete(recursive: true);
-
-  void shutdown() {
-    process.kill();
-    info.server.close(force: true);
+  Future cleanupTempDirectory() async {
+    if (tempDir == null)
+      return;
+    Directory dirToDelete = tempDir;
+    tempDir = null;
+    await dirToDelete.delete(recursive: true);
   }
 
-  var completer = new Completer();
-
-  StreamSubscription subscription;
-  subscription = socket.stream.listen((response) {
-    if (response["type"] == "print") {
-      print(response["line"]);
-    } else if (response["type"] == "loadException") {
-      shutdown();
-      completer.completeError(
-          new LoadException(path, response["message"]),
-          new Trace.current());
-    } else if (response["type"] == "error") {
-      shutdown();
-      var asyncError = RemoteException.deserialize(response["error"]);
+  process.exitCode.then((int exitCode) async {
+    info.server.close(force: true);
+    await cleanupTempDirectory();
+    if (!completer.isCompleted) {
+      String error = await process.stderr.transform(UTF8.decoder).first;
       completer.completeError(
-          new LoadException(path, asyncError.error),
-          asyncError.stackTrace);
-    } else {
-      assert(response["type"] == "success");
-      subscription.cancel();
-      completer.complete(response["tests"]);
+        new LoadException(path, error), new Trace.current());
     }
   });
 
+  Future<JSONSocket> socket = (() async {
+    return new JSONSocket(await info.socket);
+  })();
+
+  socket.then((JSONSocket socket) async {
+    await cleanupTempDirectory();
+
+    StreamSubscription subscription;
+    subscription = socket.stream.listen((response) {
+      if (response["type"] == "print") {
+        print(response["line"]);
+      } else if (response["type"] == "loadException") {
+        process.kill();
+        completer.completeError(
+            new LoadException(path, response["message"]),
+            new Trace.current());
+      } else if (response["type"] == "error") {
+        process.kill();
+        AsyncError asyncError = RemoteException.deserialize(response["error"]);
+        completer.completeError(
+            new LoadException(path, asyncError.error),
+            asyncError.stackTrace);
+      } else {
+        assert(response["type"] == "success");
+        subscription.cancel();
+        completer.complete(response["tests"]);
+      }
+    });
+  });
+
   return new RunnerSuite(const VMEnvironment(),
       (await completer.future).map((test) {
         var testMetadata = new Metadata.deserialize(test['metadata']);
@@ -127,5 +144,5 @@ void main() {
       path: path,
       platform: TestPlatform.vm,
       os: currentOS,
-      onClose: shutdown);
+      onClose: process.kill);
 }

packages/flutter_tools/lib/src/test/remote_test.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:test/src/backend/live_test.dart';
 import 'package:test/src/backend/live_test_controller.dart';
 import 'package:test/src/backend/metadata.dart';
@@ -16,23 +18,24 @@ class RemoteTest implements Test {
   final String name;
   final Metadata metadata;
 
-  final JSONSocket _socket;
+  final Future<JSONSocket> _socket;
   final int _index;
 
   RemoteTest(this.name, this.metadata, this._socket, this._index);
 
   LiveTest load(Suite suite) {
-    var controller;
-    var subscription;
+    LiveTestController controller;
+    StreamSubscription subscription;
 
-    controller = new LiveTestController(suite, this, () {
+    controller = new LiveTestController(suite, this, () async {
       controller.setState(const State(Status.running, Result.success));
 
-      _socket.send({'command': 'run', 'index': _index});
+      JSONSocket socket = await _socket;
+      socket.send({'command': 'run', 'index': _index});
 
-      subscription = _socket.stream.listen((message) {
+      subscription = socket.stream.listen((message) {
         if (message['type'] == 'error') {
-          var asyncError = RemoteException.deserialize(message['error']);
+          AsyncError asyncError = RemoteException.deserialize(message['error']);
           controller.addError(asyncError.error, asyncError.stackTrace);
         } else if (message['type'] == 'state-change') {
           controller.setState(
@@ -48,8 +51,9 @@ class RemoteTest implements Test {
           controller.completer.complete();
         }
       });
-    }, () {
-      _socket.send({'command': 'close'});
+    }, () async {
+      JSONSocket socket = await _socket;
+      socket.send({'command': 'close'});
       if (subscription != null) {
         subscription.cancel();
         subscription = null;