Add an "onPlatform" parameter to test() and group().

lib/test.dart

 // Copyright (c) 2013, 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;
 
 import 'dart:async';
 
 import 'package:path/path.dart' as p;
 
@@ skipping 32 matching lines @@
   if (declarer != null) return declarer;
   if (_globalDeclarer != null) return _globalDeclarer;
 
   // Since there's no Zone-scoped declarer, the test file is being run directly.
   // In order to run the tests, we set up our own Declarer via
   // [_globalDeclarer], and schedule a microtask to run the tests once they're
   // finished being defined.
   _globalDeclarer = new Declarer();
   scheduleMicrotask(() {
     var suite =
-      new Suite(_globalDeclarer.tests,
-            path: p.prettyUri(Uri.base),
-            platform: "VM")
-      .filter(TestPlatform.vm, os: currentOSGuess);
+        new Suite(_globalDeclarer.tests,
+              path: p.prettyUri(Uri.base),
+              platform: "VM")
+        .forPlatform(TestPlatform.vm, os: currentOSGuess);
     // TODO(nweiz): Set the exit code on the VM when issue 6943 is fixed.
     new NoIoCompactReporter([suite], color: true).run();
   });
   return _globalDeclarer;
 }
 
 // TODO(nweiz): This and other top-level functions should throw exceptions if
 // they're called after the declarer has finished declaring.
 /// Creates a new test case with the given description and body.
 ///
 /// The description will be added to the descriptions of any surrounding
 /// [group]s. If [testOn] is passed, it's parsed as a [platform selector][]; the
 /// test will only be run on matching platforms.
 ///
 /// [platform selector]: https://github.com/dart-lang/test/#platform-selector-syntax
 ///
 /// If [timeout] is passed, it's used to modify or replace the default timeout
 /// of 30 seconds. Timeout modifications take precedence in suite-group-test
 /// order, so [timeout] will also modify any timeouts set on the group or suite.
 ///
 /// If [skip] is a String or `true`, the test is skipped. If it's a String, it
 /// should explain why the test is skipped; this reason will be printed instead
 /// of running the test.
+///
+/// [onPlatform] allows tests to be configured on a platform-by-platform
+/// basis. It's a map from strings that are parsed as [PlatformSelector]s to
+/// annotation classes: [Timeout], [Skip], or lists of those. These
+/// annotations apply only on the given platforms. For example:
+///
+///     test("potentially slow test", () {
+///       // ...
+///     }, onPlatform: {
+///       // This test is especially slow on Windows.
+///       "windows": new Timeout.factor(2),
+///       "browser": [
+///         new Skip("TODO: add browser support"),
+///         // This will be slow on browsers once it works on them.
+///         new Timeout.factor(2)
+///       ]
+///     });
+///
+/// If multiple platforms match, the annotations apply in order as through
+/// they were in nested groups.
 void test(String description, body(), {String testOn, Timeout timeout,
-        skip}) =>
+        skip, Map<String, dynamic> onPlatform}) =>
     _declarer.test(description, body,
-        testOn: testOn, timeout: timeout, skip: skip);
+        testOn: testOn, timeout: timeout, skip: skip, onPlatform: onPlatform);
 
 /// Creates a group of tests.
 ///
 /// A group's description is included in the descriptions of any tests or
 /// sub-groups it contains. [setUp] and [tearDown] are also scoped to the
 /// containing group.
 ///
 /// If [testOn] is passed, it's parsed as a [platform selector][]; the test will
 /// only be run on matching platforms.
 ///
 /// [platform selector]: https://github.com/dart-lang/test/#platform-selector-syntax
 ///
 /// If [timeout] is passed, it's used to modify or replace the default timeout
 /// of 30 seconds. Timeout modifications take precedence in suite-group-test
 /// order, so [timeout] will also modify any timeouts set on the suite, and will
 /// be modified by any timeouts set on individual tests.
 ///
 /// If [skip] is a String or `true`, the group is skipped. If it's a String, it
 /// should explain why the group is skipped; this reason will be printed instead
 /// of running the group's tests.
+///
+/// [onPlatform] allows groups to be configured on a platform-by-platform
+/// basis. It's a map from strings that are parsed as [PlatformSelector]s to
+/// annotation classes: [Timeout], [Skip], or lists of those. These
+/// annotations apply only on the given platforms. For example:
+///
+///     group("potentially slow tests", () {
+///       // ...
+///     }, onPlatform: {
+///       // These tests are especially slow on Windows.
+///       "windows": new Timeout.factor(2),
+///       "browser": [
+///         new Skip("TODO: add browser support"),
+///         // They'll be slow on browsers once it works on them.
+///         new Timeout.factor(2)
+///       ]
+///     });
+///
+/// If multiple platforms match, the annotations apply in order as through
+/// they were in nested groups.
 void group(String description, void body(), {String testOn, Timeout timeout,
-        skip}) =>
+        skip, Map<String, dynamic> onPlatform}) =>
     _declarer.group(description, body,
         testOn: testOn, timeout: timeout, skip: skip);
 
 /// Registers a function to be run before tests.
 ///
 /// This function will be called before each test is run. [callback] may be
 /// asynchronous; if so, it must return a [Future].
 ///
 /// If this is called within a test group, it applies only to tests in that
 /// group. [callback] will be run after any set-up callbacks in parent groups or
@@ skipping 12 matching lines @@
 
 /// Handle an error that occurs outside of any test.
 void handleExternalError(error, String message, [stackTrace]) {
   // TODO(nweiz): handle this better.
   registerException(error, stackTrace);
 }
 
 /// Registers an exception that was caught for the current test.
 void registerException(error, [StackTrace stackTrace]) =>
     Invoker.current.handleError(error, stackTrace);