Add JSON protocol support for groups.

lib/src/runner/reporter/json.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library test.runner.reporter.json;
 
 import 'dart:async';
 import 'dart:convert';
 
+import '../../backend/group.dart';
 import '../../backend/live_test.dart';
+import '../../backend/metadata.dart';
 import '../../frontend/expect.dart';
 import '../../utils.dart';
 import '../engine.dart';
+import '../load_suite.dart';
 import '../reporter.dart';
 import '../version.dart';
 
 /// A reporter that prints machine-readable JSON-formatted test results.
 class JsonReporter implements Reporter {
   /// Whether to use verbose stack traces.
   final bool _verboseTrace;
 
   /// The engine used to run the tests.
   final Engine _engine;
 
   /// A stopwatch that tracks the duration of the full run.
   final _stopwatch = new Stopwatch();
 
   /// Whether we've started [_stopwatch].
   ///
   /// We can't just use `_stopwatch.isRunning` because the stopwatch is stopped
   /// when the reporter is paused.
   var _stopwatchStarted = false;
 
   /// Whether the reporter is paused.
   var _paused = false;
 
   /// The set of all subscriptions to various streams.
   final _subscriptions = new Set<StreamSubscription>();
 
   /// An expando that associates unique IDs with [LiveTest]s.
-  final _ids = new Map<LiveTest, int>();
+  final _liveTestIDs = new Map<LiveTest, int>();
+
+  /// An expando that associates unique IDs with [Group]s.
+  final _groupIDs = new Map<Group, int>();
 
   /// The next ID to associate with a [LiveTest].
   var _nextID = 0;
 
   /// Watches the tests run by [engine] and prints their results as JSON.
   ///
   /// If [verboseTrace] is `true`, this will print core library frames.
   static JsonReporter watch(Engine engine, {bool verboseTrace: false}) {
     return new JsonReporter._(engine, verboseTrace: verboseTrace);
   }
@@ skipping 41 matching lines @@
     _subscriptions.clear();
   }
 
   /// A callback called when the engine begins running [liveTest].
   void _onTestStarted(LiveTest liveTest) {
     if (!_stopwatchStarted) {
       _stopwatchStarted = true;
       _stopwatch.start();
     }
 
+    // Don't emit groups for load suites. They're always empty and they provide
+    // unnecessary clutter.
+    var groupIDs = liveTest.suite is LoadSuite
+        ? []
+        : _idsForGroups(liveTest.groups);
+
     var id = _nextID++;
-    _ids[liveTest] = id;
+    _liveTestIDs[liveTest] = id;
     _emit("testStart", {
       "test": {
         "id": id,
         "name": liveTest.test.name, 
-        "metadata": {
-          "skip": liveTest.test.metadata.skip,
-          "skipReason": liveTest.test.metadata.skipReason
-        }
+        "groupIDs": groupIDs,
+        "metadata": _serializeMetadata(liveTest.test.metadata)
       }
     });
 
     /// Convert the future to a stream so that the subscription can be paused or
     /// canceled.
     _subscriptions.add(liveTest.onComplete.asStream().listen((_) =>
         _onComplete(liveTest)));
 
     _subscriptions.add(liveTest.onError.listen((error) =>
         _onError(liveTest, error.error, error.stackTrace)));
 
     _subscriptions.add(liveTest.onPrint.listen((line) {
       _emit("print", {
         "testID": id,
         "message": line
       });
     }));
   }
 
+  /// Returns a list of the IDs for all the groups in [groups].
+  ///
+  /// If a group doesn't have an ID yet, this assigns one and emits a new event
+  /// for that group.
+  List<int> _idsForGroups(Iterable<Group> groups) {
+    var parentID;
+    return groups.map((group) {
+      if (_groupIDs.containsKey(group)) {
+        parentID = _groupIDs[group];
+        return parentID;
+      }
+
+      var id = _nextID++;
+      _groupIDs[group] = id;
+
+      _emit("group", {
+        "group": {
+          "id": id,
+          "parentID": parentID,
+          "name": group.name,
+          "metadata": _serializeMetadata(group.metadata)
+        }
+      });
+      parentID = id;
+      return id;
+    }).toList();
+  }
+
+  /// Serializes [metadata] into a JSON-protocol-compatible map.
+  Map _serializeMetadata(Metadata metadata) =>
+      {"skip": metadata.skip, "skipReason": metadata.skipReason};
+
   /// A callback called when [liveTest] finishes running.
   void _onComplete(LiveTest liveTest) {
     _emit("testDone", {
-      "testID": _ids[liveTest],
+      "testID": _liveTestIDs[liveTest],
       "result": liveTest.state.result.toString(),
       "hidden": !_engine.liveTests.contains(liveTest)
     });
   }
 
   /// A callback called when [liveTest] throws [error].
   void _onError(LiveTest liveTest, error, StackTrace stackTrace) {
     _emit("error", {
-      "testID": _ids[liveTest],
+      "testID": _liveTestIDs[liveTest],
       "error": error.toString(),
       "stackTrace": terseChain(stackTrace, verbose: _verboseTrace).toString(),
       "isFailure": error is TestFailure
     });
   }
 
   /// A callback called when the engine is finished running tests.
   ///
   /// [success] will be `true` if all tests passed, `false` if some tests
   /// failed, and `null` if the engine was closed prematurely.
   void _onDone(bool success) {
     cancel();
     _stopwatch.stop();
 
     _emit("done", {"success": success});
   }
 
   /// Emits an event with the given type and attributes.
   void _emit(String type, Map attributes) {
     attributes["type"] = type;
     attributes["time"] = _stopwatch.elapsed.inMilliseconds;
     print(JSON.encode(attributes));
   }
 }