Enhance dart:js interop in a backwards compatible manner.

tests/html/js_array_test.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 jsArrayTest;
+
+import 'dart:html';
+import 'dart:js';
+
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+
+_injectJs() {
+  document.body.append(new ScriptElement()
+    ..type = 'text/javascript'
+    ..innerHtml = r"""
+function callJsMethod(jsObj, jsMethodName, args) {
+  return jsObj[jsMethodName].apply(jsObj, args);
+}
+
+function jsEnumerateIndices(obj) {
+  var ret = [];
+  for(var i in obj) {
+    ret.push(i);
+  }
+  return ret;
+}
+
+function setValue(obj, index, value) {
+  return obj[index] = value;
+}
+
+function getValue(obj, index) {
+  return obj[index];
+}
+
+function checkIsArray(obj) {
+  return Array.isArray(obj);
+}
+
+function concatValues(obj) {
+  return obj.concat("a", "b", ["c", "d"], 42, {foo: 10});
+}
+
+function concatOntoArray(obj) {
+  return [1,2,3].concat(obj, "foo");
+}
+
+function repeatedConcatOntoArray(obj) {
+  return [1,2,3].concat(obj, obj);
+}
+
+function everyGreaterThanZero(obj) {
+  return obj.every(function(currentValue, index, array) {
+    return currentValue > 0;
+  });
+}
+
+function everyGreaterThanZeroCheckThisArg(obj) {
+  var j = 0;
+  return obj.every(function(currentValue, index, array) {
+    if (j != index) {
+      throw "Unxpected index";
+    }
+    j++;
+    if (array !== obj) {
+      throw "Array argument doesn't match obj";
+    }
+    return currentValue > 0;
+  });
+}
+
+function filterGreater42(obj) {
+  return obj.filter(function(currentValue, index, array) {
+    return currentValue > 42;
+  });
+}
+
+function forEachCollectResult(array, callback) {
+  var result = [];
+  array.forEach(function(currentValue) {
+    result.push(currentValue * 2);
+  });
+  return result;
+}
+
+function someEqual42(array, callback) {
+  return array.some(function(currentValue) {
+    return currentValue == 42;
+  });
+}
+
+function sortNumbersBackwards(array) {
+  return array.sort(function(a, b) {
+    return b - a;
+  });
+}
+
+function spliceDummyItems(array) {
+  return array.splice(1, 2, "quick" ,"brown", "fox");
+}
+
+function spliceTestStringArgs(array) {
+  return array.splice("1.2", "2.01", "quick" ,"brown", "fox");
+}
+
+function splicePastEnd(array) {
+  return array.splice(1, 5332, "quick" ,"brown", "fox");
+}
+
+function callJsToString(array) {
+  return array.toString();
+}
+
+function mapAddIndexToEachElement(array) {
+  return array.map(function(currentValue, index) {
+    return currentValue + index;
+  });
+}
+
+function reduceSumDoubledElements(array) {
+  return array.reduce(function(previousValue, currentValue) {
+        return previousValue + currentValue*2;
+      },
+      0);
+}
+
+// TODO(jacobr): add a test that distinguishes reduce from reduceRight.
+function reduceRightSumDoubledElements(array) {
+  return array.reduceRight(function(previousValue, currentValue) {
+        return previousValue + currentValue*2;
+      },
+      0);
+}
+
+function identical(o1, o2) {
+  return o1 === o2;
+}
+
+function getOwnPropertyDescriptorJson(array, property) {
+  return JSON.stringify(Object.getOwnPropertyDescriptor(array, property));
+}
+
+function setLength(array, len) {
+  return array.length = len;
+}
+
+function jsonStringify(o) {
+  return JSON.stringify(o);
+}
+
+// Calling a method from Dart List on an arbitrary target object.
+function callListMethodOnTarget(dartArray, target, methodName, args) {
+  return dartArray[methodName].apply(target, args);
+}
+
+""");
+}
+
+class Foo {}
+
+callJsMethod(List array, String methodName, List args) =>
+    context.callMethod("callJsMethod", [array, methodName, args]);
+
+callIndexOf(List array, value) => callJsMethod(array, "indexOf", [value]);
+callLastIndexOf(List array, value) =>
+    callJsMethod(array, "lastIndexOf", [value]);
+
+callPop(List array) => callJsMethod(array, "pop", []);
+callPush(List array, element) => callJsMethod(array, "push", [element]);
+callShift(List array) => callJsMethod(array, "shift", []);
+callReverse(List array) => callJsMethod(array, "reverse", []);
+callSetLength(List array, length) =>
+    context.callMethod("setLength", [array, length]);
+
+callListMethodOnObject(JsObject object, String methodName, List args) => context
+    .callMethod("callListMethodOnTarget", [[], object, methodName, args]);
+
+jsonStringify(JsObject object) => context.callMethod("jsonStringify", [object]);
+
+main() {
+  _injectJs();
+  useHtmlConfiguration();
+
+  group('indexOf', () {
+    var div = new DivElement();
+    var list = [3, 42, "foo", 42, div];
+    test('found', () {
+      expect(callIndexOf(list, 3), equals(0));
+      expect(callIndexOf(list, 42), equals(1));
+      expect(callIndexOf(list, "foo"), equals(2));
+      expect(callIndexOf(list, div), equals(4));
+    });
+
+    test('missing', () {
+      expect(callIndexOf(list, 31), equals(-1));
+      expect(callIndexOf(list, "42"), equals(-1));
+      expect(callIndexOf(list, null), equals(-1));
+    });
+  });
+
+  group('set length', () {
+    test('larger', () {
+      var list = ["a", "b", "c", "d"];
+      expect(callSetLength(list, 10), equals(10));
+      expect(list.length, equals(10));
+      expect(list.last, equals(null));
+      expect(list[3], equals("d"));
+    });
+
+    test('smaller', () {
+      var list = ["a", "b", "c", "d"];
+      expect(callSetLength(list, 2), equals(2));
+      expect(list.first, equals("a"));
+      expect(list.last, equals("b"));
+      expect(list.length, equals(2));
+      expect(callSetLength(list, 0), equals(0));
+      expect(list.length, equals(0));
+      expect(callSetLength(list, 2), equals(2));
+      expect(list.first, equals(null));
+    });
+
+    test('invalid', () {
+      var list = ["a", "b", "c", "d"];
+      expect(() => callSetLength(list, 2.3), throws);
+      expect(list.length, equals(4));
+      expect(() => callSetLength(list, -1), throws);
+      expect(list.length, equals(4));
+      // Make sure we are coercing to a JS number.
+      expect(callSetLength(list, "2"), equals("2"));
+      expect(list.length, equals(2));
+    });
+  });
+
+  group('join', () {
+    var list = [3, 42, "foo"];
+    var listWithDartClasses = [3, new Foo(), 42, "foo", new Object()];
+    test('default', () {
+      expect(callJsMethod(list, "join", []), equals("3,42,foo"));
+      expect(callJsMethod(listWithDartClasses, "join", []),
+          equals("3,Instance of 'Foo',42,foo,Instance of 'Object'"));
+    });
+
+    test('custom separator', () {
+      expect(callJsMethod(list, "join", ["##"]), equals("3##42##foo"));
+    });
+  });
+
+  group('lastIndexOf', () {
+    var list = [3, 42, "foo", 42];
+    test('found', () {
+      expect(callLastIndexOf(list, 3), equals(0));
+      expect(callLastIndexOf(list, 42), equals(3));
+      expect(callLastIndexOf(list, "foo"), equals(2));
+    });
+
+    test('missing', () {
+      expect(callLastIndexOf(list, 31), equals(-1));
+      expect(callLastIndexOf(list, "42"), equals(-1));
+      expect(callLastIndexOf(list, null), equals(-1));
+    });
+  });
+
+  group('pop', () {
+    test('all', () {
+      var foo = new Foo();
+      var div = new DivElement();
+      var list = [3, 42, "foo", foo, div];
+      expect(callPop(list), equals(div));
+      expect(list.length, equals(4));
+      expect(callPop(list), equals(foo));
+      expect(list.length, equals(3));
+      expect(callPop(list), equals("foo"));
+      expect(list.length, equals(2));
+      expect(callPop(list), equals(42));
+      expect(list.length, equals(1));
+      expect(callPop(list), equals(3));
+      expect(list.length, equals(0));
+      expect(callPop(list), equals(null));
+      expect(list.length, equals(0));
+    });
+  });
+
+  group('push', () {
+    test('strings', () {
+      var list = [];
+      var div = new DivElement();
+      expect(callPush(list, "foo"), equals(1));
+      expect(callPush(list, "bar"), equals(2));
+      // Calling push with 0 elements should do nothing.
+      expect(callJsMethod(list, "push", []), equals(2));
+      expect(callPush(list, "baz"), equals(3));
+      expect(callPush(list, div), equals(4));
+      expect(callJsMethod(list, "push", ["a", "b"]), equals(6));
+      expect(list, equals(["foo", "bar", "baz", div, "a", "b"]));
+    });
+  });
+
+  group('shift', () {
+    test('all', () {
+      var foo = new Foo();
+      var div = new DivElement();
+      var list = [3, 42, "foo", foo, div];
+      expect(callShift(list), equals(3));
+      expect(list.length, equals(4));
+      expect(callShift(list), equals(42));
+      expect(list.length, equals(3));
+      expect(callShift(list), equals("foo"));
+      expect(list.length, equals(2));
+      expect(callShift(list), equals(foo));
+      expect(list.length, equals(1));
+      expect(callShift(list), equals(div));
+      expect(list.length, equals(0));
+      expect(callShift(list), equals(null));
+      expect(list.length, equals(0));
+    });
+  });
+
+  group('reverse', () {
+    test('simple', () {
+      var foo = new Foo();
+      var div = new DivElement();
+      var list = [div, 42, foo];
+      callReverse(list);
+      expect(list, equals([foo, 42, div]));
+      list = [3, 42];
+      callReverse(list);
+      expect(list, equals([42, 3]));
+    });
+  });
+
+  group('slice', () {
+    test('copy', () {
+      var foo = new Foo();
+      var div = new DivElement();
+      var list = [3, 42, "foo", foo, div];
+      var copy = callJsMethod(list, "slice", []);
+      expect(identical(list, copy), isFalse);
+      expect(copy.length, equals(list.length));
+      for (var i = 0; i < list.length; i++) {
+        expect(list[i], equals(copy[i]));
+      }
+      expect(identical(list[3], copy[3]), isTrue);
+      expect(identical(list[4], copy[4]), isTrue);
+
+      copy.add("dummy");
+      expect(list.length + 1, equals(copy.length));
+    });
+
+    test('specify start', () {
+      var list = [3, 42, "foo"];
+      var copy = callJsMethod(list, "slice", [1]);
+      expect(copy.first, equals(42));
+    });
+
+    test('specify start and end', () {
+      var list = [3, 42, 92, "foo"];
+      var copy = callJsMethod(list, "slice", [1, 3]);
+      expect(copy.first, equals(42));
+      expect(copy.last, equals(92));
+    });
+
+    test('from end', () {
+      var list = [3, 42, 92, "foo"];
+      expect(callJsMethod(list, "slice", [-2]), equals([92, "foo"]));
+
+      // Past the end of the front of the array.
+      expect(callJsMethod(list, "slice", [-2, 3]), equals([92]));
+
+      // Past the end of the front of the array.
+      expect(callJsMethod(list, "slice", [-10, 2]), equals([3, 42]));
+    });
+  });
+
+  group("js snippet tests", () {
+    test("enumerate indices", () {
+      var list = ["a", "b", "c", "d"];
+      var indices = context.callMethod('jsEnumerateIndices', [list]);
+      expect(indices.length, equals(4));
+      for (int i = 0; i < 4; i++) {
+        expect(indices[i], equals('$i'));
+      }
+    });
+
+    test("set element", () {
+      var list = ["a", "b", "c", "d"];
+      context.callMethod('setValue', [list, 0, 42]);
+      expect(list[0], equals(42));
+      context.callMethod('setValue', [list, 1, 84]);
+      expect(list[1], equals(84));
+      context.callMethod(
+          'setValue', [list, 6, 100]); // Off the end of the list.
+      expect(list.length, equals(7));
+      expect(list[4], equals(null));
+      expect(list[6], equals(100));
+
+      // These tests have to be commented out because we don't persist
+      // JS proxies for Dart objects like we could/should.
+      // context.callMethod('setValue', [list, -1, "foo"]); // Not a valid array index
+      // expect(context.callMethod('getValue', [list, -1]), equals("foo"));
+      // expect(context.callMethod('getValue', [list, "-1"]), equals("foo"));
+    });
+
+    test("get element", () {
+      var list = ["a", "b", "c", "d"];
+      expect(context.callMethod('getValue', [list, 0]), equals("a"));
+      expect(context.callMethod('getValue', [list, 1]), equals("b"));
+      expect(context.callMethod('getValue', [list, 6]), equals(null));
+      expect(context.callMethod('getValue', [list, -1]), equals(null));
+
+      expect(context.callMethod('getValue', [list, "0"]), equals("a"));
+      expect(context.callMethod('getValue', [list, "1"]), equals("b"));
+    });
+
+    test("is array", () {
+      var list = ["a", "b"];
+      expect(context.callMethod("checkIsArray", [list]), isTrue);
+    });
+
+    test("property descriptors", () {
+      // This test matters to make behavior consistent with JS native arrays
+      // and to make devtools integration work well.
+      var list = ["a", "b"];
+      expect(context.callMethod("getOwnPropertyDescriptorJson", [list, 0]),
+          equals('{"value":"a",'
+              '"writable":true,'
+              '"enumerable":true,'
+              '"configurable":true}'));
+
+      expect(
+          context.callMethod("getOwnPropertyDescriptorJson", [list, "length"]),
+          equals('{"value":2,'
+              '"writable":true,'
+              '"enumerable":false,'
+              '"configurable":false}'));
+    });
+
+    test("concat js arrays", () {
+      var list = ["1", "2"];
+      // Tests that calling the concat method from JS will flatten out JS arrays
+      // We concat the array with "a", "b", ["c", "d"], 42, {foo: 10}
+      // which should generate ["1", "2", "a", "b", ["c", "d"], 42, {foo: 10}]
+      var ret = context.callMethod("concatValues", [list]);
+      expect(list.length, equals(2));
+      expect(ret.length, equals(8));
+      expect(ret[0], equals("1"));
+      expect(ret[3], equals("b"));
+      expect(ret[5], equals("d"));
+      expect(ret[6], equals(42));
+      expect(ret[7]['foo'], equals(10));
+    });
+
+    test("concat onto arrays", () {
+      // This test only passes if we have monkey patched the core Array object
+      // prototype to handle Dart Lists.
+      var list = ["a", "b"];
+      var ret = context.callMethod("concatOntoArray", [list]);
+      expect(list.length, equals(2));
+      expect(ret, equals([1, 2, 3, "a", "b", "foo"]));
+    });
+
+    test("dart arrays on dart arrays", () {
+      // This test only passes if we have monkey patched the core Array object
+      // prototype to handle Dart Lists.
+      var list = ["a", "b"];
+      var ret = callJsMethod(list, "concat", [["c", "d"], "e", ["f", "g"]]);
+      expect(list.length, equals(2));
+      expect(ret, equals(["a", "b", "c", "d", "e", "f", "g"]));
+    });
+
+    test("every greater than zero", () {
+      expect(context.callMethod("everyGreaterThanZero", [[1, 5]]), isTrue);
+      expect(context.callMethod("everyGreaterThanZeroCheckThisArg", [[1, 5]]),
+          isTrue);
+      expect(context.callMethod("everyGreaterThanZero", [[1, 0]]), isFalse);
+      expect(context.callMethod("everyGreaterThanZero", [[]]), isTrue);
+    });
+
+    test("filter greater than 42", () {
+      expect(context.callMethod("filterGreater42", [[1, 5]]), equals([]));
+      expect(context.callMethod("filterGreater42", [[43, 5, 49]]),
+          equals([43, 49]));
+      expect(context.callMethod("filterGreater42", [["43", "5", "49"]]),
+          equals(["43", "49"]));
+    });
+
+    test("for each collect result", () {
+      expect(context.callMethod("forEachCollectResult", [[1, 5, 7]]),
+          equals([2, 10, 14]));
+    });
+
+    test("some", () {
+      expect(context.callMethod("someEqual42", [[1, 5, 9]]), isFalse);
+      expect(context.callMethod("someEqual42", [[1, 42, 9]]), isTrue);
+    });
+
+    test("sort backwards", () {
+      var arr = [1, 5, 9];
+      var ret = context.callMethod("sortNumbersBackwards", [arr]);
+      expect(identical(arr, ret), isTrue);
+      expect(ret, equals([9, 5, 1]));
+    });
+
+    test("splice dummy items", () {
+      var list = [1, 2, 3, 4];
+      var removed = context.callMethod("spliceDummyItems", [list]);
+      expect(removed.length, equals(2));
+      expect(removed[0], equals(2));
+      expect(removed[1], equals(3));
+      expect(list.first, equals(1));
+      expect(list[1], equals("quick"));
+      expect(list[2], equals("brown"));
+      expect(list[3], equals("fox"));
+      expect(list.last, equals(4));
+    });
+
+    test("splice string args", () {
+      var list = [1, 2, 3, 4];
+      var removed = context.callMethod("spliceTestStringArgs", [list]);
+      expect(removed.length, equals(2));
+      expect(removed[0], equals(2));
+      expect(removed[1], equals(3));
+      expect(list.first, equals(1));
+      expect(list[1], equals("quick"));
+      expect(list[2], equals("brown"));
+      expect(list[3], equals("fox"));
+      expect(list.last, equals(4));
+    });
+
+    test("splice pastEndOfArray", () {
+      var list = [1, 2, 3, 4];
+      var removed = context.callMethod("splicePastEnd", [list]);
+      expect(removed.length, equals(3));
+      expect(list.first, equals(1));
+      expect(list.length, equals(4));
+      expect(list[1], equals("quick"));
+      expect(list[2], equals("brown"));
+      expect(list[3], equals("fox"));
+    });
+
+    test("splice both bounds past end of array", () {
+      var list = [1];
+      var removed = context.callMethod("splicePastEnd", [list]);
+      expect(removed.length, equals(0));
+      expect(list.first, equals(1));
+      expect(list.length, equals(4));
+      expect(list[1], equals("quick"));
+      expect(list[2], equals("brown"));
+      expect(list[3], equals("fox"));
+    });
+
+    test("call List method on JavaScript object", () {
+      var jsObject = new JsObject.jsify({});
+      callListMethodOnObject(jsObject, 'push', ["a"]);
+      callListMethodOnObject(jsObject, 'push', ["b"]);
+      callListMethodOnObject(jsObject, 'push', ["c", "d"]);
+      callListMethodOnObject(jsObject, 'push', []);
+
+      expect(jsonStringify(jsObject),
+          equals('{"0":"a","1":"b","2":"c","3":"d","length":4}'));
+
+      expect(callListMethodOnObject(jsObject, 'pop', []), equals("d"));
+      expect(callListMethodOnObject(jsObject, 'join', ["#"]), equals("a#b#c"));
+
+      var jsArray = new JsObject.jsify([]);
+      callListMethodOnObject(jsArray, 'push', ["a"]);
+      callListMethodOnObject(jsArray, 'push', ["b"]);
+      callListMethodOnObject(jsArray, 'push', ["c", "d"]);
+      callListMethodOnObject(jsArray, 'push', []);
+
+      expect(jsonStringify(jsArray), equals('["a","b","c","d"]'));
+    });
+  });
+
+  // This test group is disabled until we figure out an efficient way to
+  // distinguish between "array" Dart List types and non-array Dart list types.
+  /*
+  group('Non-array Lists', () {
+    test('opaque proxy', () {
+      // Dartium could easily support making LinkedList and all other classes
+      // implementing List behave like a JavaScript array but that would
+      // be challenging to implement in dart2js until browsers support ES6.
+      var list = ["a", "b", "c", "d"];
+      var listView = new UnmodifiableListView(list.getRange(1,3));
+      expect(listView is List, isTrue);
+      expect(listView.length, equals(2));
+      expect(context.callMethod("checkIsArray", [listView]), isFalse);
+      expect(context.callMethod("checkIsArray", [listView.toList()]), isTrue);
+      expect(context.callMethod("getOwnPropertyDescriptorJson",
+          [listView, "length"]), equals("null"));
+    });
+  });
+  */
+}