fixes #168, dart:js implementation with a test

test/browser/js_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 jsTest;
+
+import 'dart:js';
+
+// TODO(jmesserly): get this from a package.
+import 'dom.dart';
+
+// TODO(jmesserly): use the real package:test. It's not possible yet because
+// it depends on async/await which we don't support.
+//
+// import 'package:test/test.dart';

[vsm, 2015/06/24 23:16:15]

Do the tests here run yet? 

Are these tests the same as those under test/html/js_test in the main repo?

[Jennifer Messerly, 2015/06/25 20:11:27]

basically, yes & yes

I may have removed some commented out tests from the original. I tried to keep
everything that made sense.

+
+class Foo {
+  final JsObject _proxy;
+
+  Foo(num a) : this._proxy = new JsObject(context['Foo'], [a]);
+
+  JsObject toJs() => _proxy;
+
+  num get a => _proxy['a'];
+  num bar() => _proxy.callMethod('bar');
+}
+
+class Color {
+  static final RED = new Color._("red");
+  static final BLUE = new Color._("blue");
+  String _value;
+  Color._(this._value);
+  String toJs() => this._value;
+}
+
+class TestDartObject {}
+
+class Callable {
+  call() => 'called';
+}
+
+main() {
+  group('identity', () {
+
+    test('context instances should be identical', () {
+      var c1 = context;
+      var c2 = context;
+      expect(identical(c1, c2), true);
+    });
+
+    // TODO(jacobr): switch from equals to identical when dartium supports
+    // maintaining proxy equality.
+    test('identical JS functions should have equal proxies', () {
+      var f1 = context['Object'];
+      var f2 = context['Object'];
+      expect(f1, equals(f2));
+    });
+
+    // TODO(justinfagnani): old tests duplicate checks above, remove
+    // on test next cleanup pass
+    test('test proxy equality', () {
+      var foo1 = new JsObject(context['Foo'], [1]);
+      var foo2 = new JsObject(context['Foo'], [2]);
+      context['foo1'] = foo1;
+      context['foo2'] = foo2;
+      expect(foo1, isNot(context['foo2']));
+      expect(foo2, context['foo2']);
+      context.deleteProperty('foo1');
+      context.deleteProperty('foo2');
+    });
+
+    test('retrieve same dart Object', () {
+      final obj = new Object();
+      context['obj'] = obj;
+      expect(context['obj'], same(obj));
+      context.deleteProperty('obj');
+    });
+
+    group('caching', () {
+      test('JS->Dart', () {
+        // Test that we are not pulling cached proxy from the prototype
+        // when asking for a proxy for the object.
+        final proto = context['someProto'];
+        expect(proto['role'], 'proto');
+        final obj = context['someObject'];
+        expect(obj['role'], 'object');
+      });
+    });
+
+  });
+
+  group('context', () {
+
+    test('read global field', () {
+      expect(context['x'], 42);
+      expect(context['y'], null);
+    });
+
+    test('read global field with underscore', () {
+      expect(context['_x'], 123);
+      expect(context['y'], null);
+    });
+
+    test('write global field', () {
+      context['y'] = 42;
+      expect(context['y'], 42);
+    });
+
+  });
+
+  group('new JsObject()', () {
+
+    test('new Foo()', () {
+      var foo = new JsObject(context['Foo'], [42]);
+      expect(foo['a'], 42);
+      expect(foo.callMethod('bar'), 42);
+      expect(() => foo.callMethod('baz'), throwsA(isNoSuchMethodError));
+    });
+
+    test('new container.Foo()', () {
+      final Foo2 = context['container']['Foo'];
+      final foo = new JsObject(Foo2, [42]);
+      expect(foo['a'], 42);
+      expect(Foo2['b'], 38);
+    });
+
+    test('new Array()', () {
+      var a = new JsObject(context['Array']);
+      expect(a, (a) => a is JsArray);
+
+      // Test that the object still behaves via the base JsObject interface.
+      // JsArray specific tests are below.
+      expect(a['length'], 0);
+
+      a.callMethod('push', ["value 1"]);
+      expect(a['length'], 1);
+      expect(a[0], "value 1");
+
+      a.callMethod('pop');
+      expect(a['length'], 0);
+    });
+
+    test('new Date()', () {
+      final a = new JsObject(context['Date']);
+      expect(a.callMethod('getTime'), isNotNull);
+    });
+
+    test('new Date(12345678)', () {
+      final a = new JsObject(context['Date'], [12345678]);
+      expect(a.callMethod('getTime'), 12345678);
+    });
+
+    test('new Date("December 17, 1995 03:24:00 GMT")', () {
+      final a = new JsObject(context['Date'],
+          ["December 17, 1995 03:24:00 GMT"]);
+      expect(a.callMethod('getTime'), 819170640000);
+    });
+
+    test('new Date(1995,11,17)', () {
+      // Note: JS Date counts months from 0 while Dart counts from 1.
+      final a = new JsObject(context['Date'], [1995, 11, 17]);
+      final b = new DateTime(1995, 12, 17);
+      expect(a.callMethod('getTime'), b.millisecondsSinceEpoch);
+    });
+
+    test('new Date(1995,11,17,3,24,0)', () {
+      // Note: JS Date counts months from 0 while Dart counts from 1.
+      final a = new JsObject(context['Date'],
+          [1995, 11, 17, 3, 24, 0]);
+      final b = new DateTime(1995, 12, 17, 3, 24, 0);
+      expect(a.callMethod('getTime'), b.millisecondsSinceEpoch);
+    });
+
+    test('new Object()', () {
+      final a = new JsObject(context['Object']);
+      expect(a, isNotNull);
+
+      a['attr'] = "value";
+      expect(a['attr'], "value");
+    });
+
+    test(r'new RegExp("^\w+$")', () {
+      final a = new JsObject(context['RegExp'], [r'^\w+$']);
+      expect(a, isNotNull);
+      expect(a.callMethod('test', ['true']), true);
+      expect(a.callMethod('test', [' false']), false);
+    });
+
+    test('js instantiation via map notation : new Array()', () {
+      final a = new JsObject(context['Array']);
+      expect(a, isNotNull);
+      expect(a['length'], 0);
+
+      a.callMethod('push', ["value 1"]);
+      expect(a['length'], 1);
+      expect(a[0], "value 1");
+
+      a.callMethod('pop');
+      expect(a['length'], 0);
+    });
+
+    test('js instantiation via map notation : new Date()', () {
+      final a = new JsObject(context['Date']);
+      expect(a.callMethod('getTime'), isNotNull);
+    });
+
+    test('>10 parameters', () {
+      final o = new JsObject(context['Baz'], [1,2,3,4,5,6,7,8,9,10,11]);
+      for (var i = 1; i <= 11; i++) {
+        expect(o["f$i"], i);
+      }
+      expect(o['constructor'], context['Baz']);
+    });
+  });
+
+  group('JsFunction and callMethod', () {
+
+    test('new JsObject can return a JsFunction', () {
+      var f = new JsObject(context['Function']);
+      expect(f, (a) => a is JsFunction);
+    });
+
+    test('JsFunction.apply on a function defined in JS', () {
+      expect(context['razzle'].apply([]), 42);
+    });
+
+    test('JsFunction.apply on a function that uses "this"', () {
+      var object = new Object();
+      expect(context['returnThis'].apply([], thisArg: object), same(object));
+    });
+
+    test('JsObject.callMethod on a function defined in JS', () {
+      expect(context.callMethod('razzle'), 42);
+      expect(() => context.callMethod('dazzle'), throwsA(isNoSuchMethodError));
+    });
+
+    test('callMethod with many arguments', () {
+      expect(context.callMethod('varArgs', [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]),
+        55);
+    });
+
+    test('access a property of a function', () {
+      expect(context.callMethod('Bar'), "ret_value");
+      expect(context['Bar']['foo'], "property_value");
+    });
+
+  });
+
+  group('JsArray', () {
+
+    test('new JsArray()', () {
+      var array = new JsArray();
+      var arrayType = context['Array'];
+      expect(array.instanceof(arrayType), true);
+      expect(array, []);
+      // basic check that it behaves like a List
+      array.addAll([1, 2, 3]);
+      expect(array, [1, 2, 3]);
+    });
+
+    test('new JsArray.from()', () {
+      var array = new JsArray.from([1, 2, 3]);
+      var arrayType = context['Array'];
+      expect(array.instanceof(arrayType), true);
+      expect(array, [1, 2, 3]);
+    });
+
+    test('get Array from JS', () {
+      context['a'] = new JsObject(context['Array'], [1, 2, 3]);
+      expect(context.callMethod('isPropertyInstanceOf',
+          ['a', context['Array']]), true);
+      var a = context['a'];
+      expect(a, (a) => a is JsArray);
+      expect(a, [1, 2, 3]);
+      context.deleteProperty('a');
+    });
+
+    test('pass Array to JS', () {
+      context['a'] = [1, 2, 3];
+      expect(context.callMethod('isPropertyInstanceOf',
+          ['a', context['Array']]), false);
+      var a = context['a'];
+      expect(a, (a) => a is List);
+      expect(a, isNot((a) => a is JsArray));
+      expect(a, [1, 2, 3]);
+      context.deleteProperty('a');
+    });
+
+    test('[]', () {
+      var array = new JsArray.from([1, 2]);
+      expect(array[0], 1);
+      expect(array[1], 2);
+      expect(() => array[-1], throwsA(isRangeError));
+      expect(() => array[2], throwsA(isRangeError));
+    });
+
+   test('[]=', () {
+      var array = new JsArray.from([1, 2]);
+      array[0] = 'd';
+      array[1] = 'e';
+      expect(array, ['d', 'e']);
+      expect(() => array[-1] = 3, throwsA(isRangeError));
+      expect(() => array[2] = 3, throwsA(isRangeError));
+    });
+
+    test('length', () {
+      var array = new JsArray.from([1, 2, 3]);
+      expect(array.length, 3);
+      array.add(4);
+      expect(array.length, 4);
+      array.length = 2;
+      expect(array, [1, 2]);
+      array.length = 3;
+      expect(array, [1, 2, null]);
+    });
+ 
+     test('add', () {
+      var array = new JsArray();
+      array.add('a');
+      expect(array, ['a']);
+      array.add('b');
+      expect(array, ['a', 'b']);
+    });
+
+    test('addAll', () {
+      var array = new JsArray();
+      array.addAll(['a', 'b']);
+      expect(array, ['a', 'b']);
+      // make sure addAll can handle Iterables
+      array.addAll(new Set.from(['c']));
+      expect(array, ['a', 'b', 'c']);
+    });
+
+    test('insert', () {
+      var array = new JsArray.from([]);
+      array.insert(0, 'b');
+      expect(array, ['b']);
+      array.insert(0, 'a');
+      expect(array, ['a', 'b']);
+      array.insert(2, 'c');
+      expect(array, ['a', 'b', 'c']);
+      expect(() => array.insert(4, 'e'), throwsA(isRangeError));
+      expect(() => array.insert(-1, 'e'), throwsA(isRangeError));
+    });
+
+    test('removeAt', () {
+      var array = new JsArray.from(['a', 'b', 'c']);
+      expect(array.removeAt(1), 'b');
+      expect(array, ['a', 'c']);
+      expect(() => array.removeAt(2), throwsA(isRangeError));
+      expect(() => array.removeAt(-1), throwsA(isRangeError));
+    });
+
+    test('removeLast', () {
+      var array = new JsArray.from(['a', 'b', 'c']);
+      expect(array.removeLast(), 'c');
+      expect(array, ['a', 'b']);
+      array.length = 0;
+      expect(() => array.removeLast(), throwsA(isRangeError));
+    });
+
+    test('removeRange', () {
+      var array = new JsArray.from(['a', 'b', 'c', 'd']);
+      array.removeRange(1, 3);
+      expect(array, ['a', 'd']);
+      expect(() => array.removeRange(-1, 2), throwsA(isRangeError));
+      expect(() => array.removeRange(0, 3), throwsA(isRangeError));
+      expect(() => array.removeRange(2, 1), throwsA(isRangeError));
+    });
+
+    test('setRange', () {
+      var array = new JsArray.from(['a', 'b', 'c', 'd']);
+      array.setRange(1, 3, ['e', 'f']);
+      expect(array, ['a', 'e', 'f', 'd']);
+      array.setRange(3, 4, ['g', 'h', 'i'], 1);
+      expect(array, ['a', 'e', 'f', 'h']);
+    });
+
+    test('sort', () {
+      var array = new JsArray.from(['c', 'a', 'b']);
+      array.sort();
+      expect(array, ['a', 'b', 'c']);
+    });
+
+    test('sort with a Comparator', () {
+      var array = new JsArray.from(['c', 'a', 'b']);
+      array.sort((a, b) => -(a.compareTo(b)));
+      expect(array, ['c', 'b', 'a']);
+    });
+
+  });
+
+  group('JsObject.fromBrowserObject()', () {
+
+    test('Nodes are proxied', () {
+      var node = new JsObject.fromBrowserObject(document.createElement('div'));
+      context.callMethod('addTestProperty', [node]);
+      expect(node is JsObject, true);
+      expect(node.instanceof(context['HTMLDivElement']), true);
+      expect(node['testProperty'], 'test');
+    });
+
+    test('primitives and null throw ArgumentError', () {
+      for (var v in ['a', 1, 2.0, true, null]) {
+        expect(() => new JsObject.fromBrowserObject(v),
+            throwsA((a) => a is ArgumentError));
+      }
+    });
+
+  });
+
+  group('Dart functions', () {
+    test('invoke Dart callback from JS', () {
+      expect(() => context.callMethod('invokeCallback'), throws);
+
+      context['callback'] = () => 42;
+      expect(context.callMethod('invokeCallback'), 42);
+
+      context.deleteProperty('callback');
+    });
+
+    test('callback as parameter', () {
+      expect(context.callMethod('getTypeOf', [context['razzle']]),
+          "function");
+    });
+
+    test('invoke Dart callback from JS with this', () {
+      // A JavaScript constructor implemented in Dart using 'this'
+      final constructor = new JsFunction.withThis(($this, arg1) {
+        $this['a'] = 42;
+      });
+      var o = new JsObject(constructor, ["b"]);
+      expect(o['a'], 42);
+    });
+
+    test('invoke Dart callback from JS with 11 parameters', () {
+      context['callbackWith11params'] = (p1, p2, p3, p4, p5, p6, p7,
+          p8, p9, p10, p11) => '$p1$p2$p3$p4$p5$p6$p7$p8$p9$p10$p11';
+      expect(context.callMethod('invokeCallbackWith11params'),
+          '1234567891011');
+    });
+
+    test('return a JS proxy to JavaScript', () {
+      var result = context.callMethod('testJsMap',
+          [() => new JsObject.jsify({'value': 42})]);
+      expect(result, 42);
+    });
+
+    test('emulated functions should be callable in JS', () {
+      context['callable'] = new Callable();
+      var result = context.callMethod('callable');
+      expect(result, 'called');
+      context.deleteProperty('callable');
+    }, skip: "https://github.com/dart-lang/dev_compiler/issues/244");
+
+  });
+
+  group('JsObject.jsify()', () {
+
+    test('convert a List', () {
+      final list = [1, 2, 3, 4, 5, 6, 7, 8];
+      var array = new JsObject.jsify(list);
+      expect(context.callMethod('isArray', [array]), true);
+      expect(array['length'], list.length);
+      for (var i = 0; i < list.length ; i++) {
+        expect(array[i], list[i]);
+      }
+    });
+
+    test('convert an Iterable', () {
+      final set = new Set.from([1, 2, 3, 4, 5, 6, 7, 8]);
+      var array = new JsObject.jsify(set);
+      expect(context.callMethod('isArray', [array]), true);
+      expect(array['length'], set.length);
+      for (var i = 0; i < array['length'] ; i++) {
+        expect(set.contains(array[i]), true);
+      }
+    });
+
+    test('convert a Map', () {
+      var map = {'a': 1, 'b': 2, 'c': 3};
+      var jsMap = new JsObject.jsify(map);
+      expect(!context.callMethod('isArray', [jsMap]), true);
+      for (final key in map.keys) {
+        expect(context.callMethod('checkMap', [jsMap, key, map[key]]), true);
+      }
+    });
+
+    test('deep convert a complex object', () {
+      final object = {
+        'a': [1, [2, 3]],
+        'b': {
+          'c': 3,
+          'd': new JsObject(context['Foo'], [42])
+        },
+        'e': null
+      };
+      var jsObject = new JsObject.jsify(object);
+      expect(jsObject['a'][0], object['a'][0]);
+      expect(jsObject['a'][1][0], object['a'][1][0]);
+      expect(jsObject['a'][1][1], object['a'][1][1]);
+      expect(jsObject['b']['c'], object['b']['c']);
+      expect(jsObject['b']['d'], object['b']['d']);
+      expect(jsObject['b']['d'].callMethod('bar'), 42);
+      expect(jsObject['e'], null);
+    });
+
+    test('throws if object is not a Map or Iterable', () {
+      expect(() => new JsObject.jsify('a'),
+          throwsA((a) => a is ArgumentError));
+    });
+  });
+
+  group('JsObject methods', () {
+
+    test('hashCode and ==', () {
+      final o1 = context['Object'];
+      final o2 = context['Object'];
+      expect(o1 == o2, true);
+      expect(o1.hashCode == o2.hashCode, true);
+      final d = context['document'];
+      expect(o1 == d, false);
+    });
+
+    test('toString', () {
+      var foo = new JsObject(context['Foo'], [42]);
+      expect(foo.toString(), "I'm a Foo a=42");
+      var container = context['container'];
+      expect(container.toString(), "[object Object]");
+    });
+
+    test('toString returns a String even if the JS object does not', () {
+      var foo = new JsObject(context['Liar']);
+      expect(foo.callMethod('toString'), 1);
+      expect(foo.toString(), '1');
+    });
+
+    test('instanceof', () {
+      var foo = new JsObject(context['Foo'], [1]);
+      expect(foo.instanceof(context['Foo']), true);
+      expect(foo.instanceof(context['Object']), true);
+      expect(foo.instanceof(context['String']), false);
+    });
+
+    test('deleteProperty', () {
+      var object = new JsObject.jsify({});
+      object['a'] = 1;
+      expect(context['Object'].callMethod('keys', [object])['length'], 1);
+      expect(context['Object'].callMethod('keys', [object])[0], "a");
+      object.deleteProperty("a");
+      expect(context['Object'].callMethod('keys', [object])['length'], 0);
+    });
+
+    test('hasProperty', () {
+      var object = new JsObject.jsify({});
+      object['a'] = 1;
+      expect(object.hasProperty('a'), true);
+      expect(object.hasProperty('b'), false);
+    });
+
+    test('[] and []=', () {
+      final myArray = context['myArray'];
+      expect(myArray['length'], 1);
+      expect(myArray[0], "value1");
+      myArray[0] = "value2";
+      expect(myArray['length'], 1);
+      expect(myArray[0], "value2");
+
+      final foo = new JsObject(context['Foo'], [1]);
+      foo["getAge"] = () => 10;
+      expect(foo.callMethod('getAge'), 10);
+    });
+
+  });
+
+  group('transferrables', () {
+
+    group('JS->Dart', () {
+
+      test('DateTime', () {
+        var date = context.callMethod('getNewDate');
+        expect(date is DateTime, true);
+      });
+
+      test('window', () {
+        expect(context['window'] is Window, true);
+      });
+
+      test('foreign browser objects should be proxied', () {
+        var iframe = document.createElement('iframe');
+        document.body.appendChild(iframe);
+        var proxy = new JsObject.fromBrowserObject(iframe);
+
+        // Window
+        var contentWindow = proxy['contentWindow'];
+        expect(contentWindow, isNot((a) => a is Window));
+        expect(contentWindow, (a) => a is JsObject);
+
+        // Node
+        var foreignDoc = contentWindow['document'];
+        expect(foreignDoc, isNot((a) => a is Node));
+        expect(foreignDoc, (a) => a is JsObject);
+
+        // Event
+        var clicked = false;
+        foreignDoc['onclick'] = (e) {
+          expect(e, isNot((a) => a is Event));
+          expect(e, (a) => a is JsObject);
+          clicked = true;
+        };
+
+        context.callMethod('fireClickEvent', [contentWindow]);
+        expect(clicked, true);
+      });
+
+      test('document', () {
+        expect(context['document'] is Document, true);
+      });
+
+      test('Blob', () {
+        var blob = context.callMethod('getNewBlob');
+        expect(blob is Blob, true);
+        expect(blob.type, 'text/html');
+      });
+
+      test('unattached DivElement', () {
+        var node = context.callMethod('getNewDivElement');
+        expect(node is DivElement, true);
+      });
+
+      test('Event', () {
+        var event = context.callMethod('getNewEvent');
+        expect(event is Event, true);
+      });
+
+      test('ImageData', () {
+        var node = context.callMethod('getNewImageData');
+        expect(node is ImageData, true);
+      });
+
+    });
+
+    group('Dart->JS', () {
+
+      test('Date', () {
+        context['o'] = new DateTime(1995, 12, 17);
+        var dateType = context['Date'];
+        expect(context.callMethod('isPropertyInstanceOf', ['o', dateType]),
+            true);
+        context.deleteProperty('o');
+      });
+
+      test('window', () {
+        context['o'] = window;
+        var windowType = context['Window'];
+        expect(context.callMethod('isPropertyInstanceOf', ['o', windowType]),
+            true);
+        context.deleteProperty('o');
+      });
+
+      test('document', () {
+        context['o'] = document;
+        var documentType = context['Document'];
+        expect(context.callMethod('isPropertyInstanceOf', ['o', documentType]),
+            true);
+        context.deleteProperty('o');
+      });
+
+      test('Blob', () {
+        var fileParts = ['<a id="a"><b id="b">hey!</b></a>'];
+        context['o'] = new Blob(fileParts, type: 'text/html');
+        var blobType = context['Blob'];
+        expect(context.callMethod('isPropertyInstanceOf', ['o', blobType]),
+            true);
+        context.deleteProperty('o');
+      });
+
+      test('unattached DivElement', () {
+        context['o'] = document.createElement('div');
+        var divType = context['HTMLDivElement'];
+        expect(context.callMethod('isPropertyInstanceOf', ['o', divType]),
+            true);
+        context.deleteProperty('o');
+      });
+
+      test('Event', () {
+        context['o'] = new CustomEvent('test');
+        var eventType = context['Event'];
+        expect(context.callMethod('isPropertyInstanceOf', ['o', eventType]),
+            true);
+        context.deleteProperty('o');
+      });
+
+      // this test fails in IE9 for very weird, but unknown, reasons
+      // the expression context['ImageData'] fails if useHtmlConfiguration()
+      // is called, or if the other tests in this file are enabled
+      test('ImageData', () {
+        CanvasElement canvas = document.createElement('canvas');
+        var ctx = canvas.getContext('2d') as CanvasRenderingContext2D;
+        context['o'] = ctx.createImageData(1, 1);
+        var imageDataType = context['ImageData'];
+        expect(context.callMethod('isPropertyInstanceOf', ['o', imageDataType]),
+            true);
+        context.deleteProperty('o');
+      });
+
+    });
+  });
+
+}
+
+final console = (window as dynamic).console;

[vsm, 2015/06/24 23:16:15]

Move the code below to a separate 'unittest' file?

[Jennifer Messerly, 2015/06/25 20:11:27]

sure. I hope it doesn't stick around long, though.

+
+void group(String name, void body()) {
+  console.group(name);
+  body();
+  console.groupEnd(name);
+}
+
+void test(String name, void body(), {String skip}) {
+  if (skip != null) {
+    console.warn('SKIP $name: $skip');
+    return;
+  }
+  console.log(name);
+  try {
+    body();
+  } catch(e) {
+    console.error(e);
+  }
+}
+
+void expect(Object actual, matcher) {
+  if (matcher is! Matcher) matcher = equals(matcher);
+  if (!matcher(actual)) {
+    throw 'Expect failed to match $actual with $matcher';
+  }
+}
+
+Matcher equals(Object expected) {
+  return (actual) {
+    if (expected is List && actual is List) {
+      int len = expected.length;
+      if (len != actual.length) return false;
+      for (int i = 0; i < len; i++) {
+        if (!equals(expected[i])(actual[i])) return false;
+      }
+      return true;
+    } else {
+      return expected == actual;
+    }
+  };
+}
+
+Matcher same(Object expected) => (actual) => identical(expected, actual);
+Matcher isNot(matcher) {
+  if (matcher is! Matcher) matcher = equals(matcher);
+  return (actual) => !matcher(actual);
+}
+
+bool isNull(actual) => actual == null;
+final Matcher isNotNull = isNot(isNull);
+bool isRangeError(actual) => actual is RangeError;
+bool isNoSuchMethodError(actual) => actual is NoSuchMethodError;
+
+Matcher throwsA(matcher) {
+  if (matcher is! Matcher) matcher = equals(matcher);
+  return (actual) {
+    try {
+      actual();
+      return false;
+    } catch(e) {
+      return matcher(e);
+    }
+  };
+}
+
+final Matcher throws = throwsA((a) => true);
+
+typedef Matcher(actual);