Add a JSON reporter.

lib/src/runner.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;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:async/async.dart';
 
 import 'backend/test_platform.dart';
 import 'runner/application_exception.dart';
 import 'runner/configuration.dart';
 import 'runner/engine.dart';
 import 'runner/load_exception.dart';
 import 'runner/load_suite.dart';
 import 'runner/loader.dart';
 import 'runner/reporter.dart';
 import 'runner/reporter/compact.dart';
 import 'runner/reporter/expanded.dart';
+import 'runner/reporter/json.dart';
 import 'runner/runner_suite.dart';
 import 'util/io.dart';
 import 'utils.dart';
 
 /// A class that loads and runs tests based on a [Configuration].
 ///
 /// This maintains a [Loader] and an [Engine] and passes test suites from one to
 /// the other, as well as printing out tests with a [CompactReporter] or an
 /// [ExpandedReporter].
 class Runner {
@@ skipping 14 matching lines @@
 
   /// The memoizer for ensuring [close] only runs once.
   final _closeMemo = new AsyncMemoizer();
   bool get _closed => _closeMemo.hasRun;
 
   /// Creates a new runner based on [configuration].
   factory Runner(Configuration config) {
     var loader = new Loader(config);
     var engine = new Engine(concurrency: config.concurrency);
 
-    var watch = config.reporter == "compact"
-        ? CompactReporter.watch
-        : ExpandedReporter.watch;
+    var reporter;
+    switch (config.reporter) {
+      case "compact":
+      case "expanded":
+        var watch = config.reporter == "compact"
+            ? CompactReporter.watch
+            : ExpandedReporter.watch;
 
-    var reporter = watch(
-        engine,
-        color: config.color,
-        verboseTrace: config.verboseTrace,
-        printPath: config.paths.length > 1 ||
-            new Directory(config.paths.single).existsSync(),
-        printPlatform: config.platforms.length > 1);
+        reporter = watch(
+            engine,
+            color: config.color,
+            verboseTrace: config.verboseTrace,
+            printPath: config.paths.length > 1 ||
+                new Directory(config.paths.single).existsSync(),
+            printPlatform: config.platforms.length > 1);
+        break;
+
+      case "json":
+        reporter = JsonReporter.watch(engine,
+            verboseTrace: config.verboseTrace);
+        break;
+    }
 
     return new Runner._(config, loader, engine, reporter);
   }
 
   Runner._(this._config, this._loader, this._engine, this._reporter);
 
   /// Starts the runner.
   ///
   /// This starts running tests and printing their progress. It returns whether
   /// or not they ran successfully.
@@ skipping 169 matching lines @@
 
       await inCompletionOrder([
         suite.environment.displayPause(),
         cancelableNext(stdinLines)
       ]).first;
     } finally {
       _reporter.resume();
     }
   }
 }