Support JSON output for pub build.

sdk/lib/_internal/pub/test/build/outputs_results_to_json_test.dart

Index: sdk/lib/_internal/pub/test/build/outputs_results_to_json_test.dart
diff --git a/sdk/lib/_internal/pub/test/build/outputs_results_to_json_test.dart b/sdk/lib/_internal/pub/test/build/outputs_results_to_json_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..3be420c61c5880d4ae1a39435d60aafa0e4dac44
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/build/outputs_results_to_json_test.dart
@@ -0,0 +1,52 @@
+// Copyright (c) 2014, 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.
+
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+
+main() {
+  initConfig();
+
+  integration("outputs results to JSON in a successful build", () {
+    // Dart2js can take a long time to compile dart code, so we increase the
+    // timeout to cope with that.
+    currentSchedule.timeout *= 3;
+
+    d.dir(appPath, [
+      d.appPubspec(),
+      d.dir('web', [
+        d.file('main.dart', 'void main() => print("hello");')
+      ])
+    ]).create();
+
+    schedulePub(args: ["build", "--format", "json"],
+        outputJson: {
+          'buildResult': 'success',
+          'outputDirectory': 'build',
+          'numFiles': 3,
+          'log': [
+            {
+              'level': 'Info',
+              'transformer': {
+                'name': 'Dart2JS',
+                'primaryInput': {'package': 'myapp', 'path': 'web/main.dart'}
+              },
+              'assetId': {'package': 'myapp', 'path': 'web/main.dart'},
+              'message': 'Compiling myapp|web/main.dart...'
+            },
+            {
+              'level': 'Info',
+              'transformer': {
+                'name': 'Dart2JS',
+                'primaryInput': {'package': 'myapp', 'path': 'web/main.dart'}
+              },
+              'assetId': {'package': 'myapp', 'path': 'web/main.dart'},
+              'message': contains(r'to compile myapp|web/main.dart.')
+            }
+          ]
+        });
+  });
+}