Fix mocks on js types

Change-Id: I4b07fd0fc5d3771d93f250b5ba51261ea5bef001
Reviewed-on: https://dart-review.googlesource.com/35480
Commit-Queue: Vijay Menon <vsm@google.com>
Reviewed-by: Jacob Richman <jacobr@google.com>
Reviewed-by: Jenny Messerly <jmesserly@google.com>

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/types.dart

@@ -82,6 +82,8 @@ class Dynamic extends TypeRep {
   check_T(object) => object;
 }
 
+bool _isJsObject(obj) => JS('bool', '# === #', getReifiedType(obj), jsobject);
+
 class LazyJSType extends TypeRep {
   final Function() _rawJSType;
   final String _dartName;
@@ -90,29 +92,36 @@ class LazyJSType extends TypeRep {
 
   toString() => typeName(_rawJSType());
 
-  rawJSTypeForCheck() {
+  _raw() {
     var raw = _rawJSType();
+    if (raw == null) {
+      _warn('Cannot find native JavaScript type ($_dartName) for type check');
+    }
+    return raw;
+  }
+
+  rawJSTypeForCheck() {
+    var raw = _raw();
     if (raw != null) return raw;
-    _warn('Cannot find native JavaScript type ($_dartName) for type check');
-    return JS('', '#.Object', global_);
+    // Treat as anonymous: return true for any JS object.
+    return jsobject;
   }
 
-  @JSExportName('is')
-  bool is_T(obj) {
-    return JS('bool', '# instanceof #', obj, rawJSTypeForCheck());
+  bool isRawType(obj) {
+    var raw = _raw();
+    if (raw != null) return JS('bool', '# instanceof #', obj, raw);
+    // Treat as anonymous: return true for any JS object.
+    return _isJsObject(obj);
   }
 
+  @JSExportName('is')
+  bool is_T(obj) => isRawType(obj) || instanceOf(obj, this);
+
   @JSExportName('as')
-  as_T(obj) =>
-      JS('bool', '# instanceof #', obj, rawJSTypeForCheck()) || obj == null
-          ? obj
-          : castError(obj, this, false);
+  as_T(obj) => obj == null || is_T(obj) ? obj : castError(obj, this, false);
 
   @JSExportName('_check')
-  check_T(obj) =>
-      JS('bool', '# instanceof #', obj, rawJSTypeForCheck()) || obj == null
-          ? obj
-          : castError(obj, this, true);
+  check_T(obj) => obj == null || is_T(obj) ? obj : castError(obj, this, true);
 }
 
 /// An anonymous JS type
@@ -124,20 +133,13 @@ class AnonymousJSType extends TypeRep {
   toString() => _dartName;
 
   @JSExportName('is')
-  bool is_T(obj) => JS('bool', '# === # || #', getReifiedType(obj), jsobject,
-      instanceOf(obj, this));
+  bool is_T(obj) => _isJsObject(obj) || instanceOf(obj, this);
 
   @JSExportName('as')
-  as_T(obj) =>
-      JS('bool', '# == null || # === #', obj, getReifiedType(obj), jsobject)
-          ? obj
-          : cast(obj, this, false);
+  as_T(obj) => obj == null || _isJsObject(obj) ? obj : cast(obj, this, false);
 
   @JSExportName('_check')
-  check_T(obj) =>
-      JS('bool', '# == null || # === #', obj, getReifiedType(obj), jsobject)
-          ? obj
-          : cast(obj, this, true);
+  check_T(obj) => obj == null || _isJsObject(obj) ? obj : cast(obj, this, true);
 }
 
 void _warn(arg) {
@@ -963,9 +965,6 @@ bool _isSubtype(t1, t2, isCovariant) => JS('', '''(() => {
     // All JS types are subtypes of anonymous JS types.
     return $t1 === $jsobject;
   }
-  if ($t2 instanceof $LazyJSType) {
-    return $_isSubtype($t1, $t2.rawJSTypeForCheck(), isCovariant);
-  }
 
   // Function subtyping.
 
@@ -1036,6 +1035,12 @@ isClassSubType(t1, t2, isCovariant) => JS('', '''(() => {
   // I.e., given T1, ..., Tn where at least one Ti != dynamic we disallow:
   // - S !<: S<T1, ..., Tn>
   // - S<dynamic, ..., dynamic> !<: S<T1, ..., Tn>
+  
+  // If we have lazy JS types, unwrap them.  This will effectively
+  // reduce to a prototype check below.
+  if ($t1 instanceof $LazyJSType) $t1 = $t1.rawJSTypeForCheck();
+  if ($t2 instanceof $LazyJSType) $t2 = $t2.rawJSTypeForCheck();
+
   if ($t1 == $t2) return true;
 
   if ($t1 == $Object) return false;

tests/lib_2/html/js_mock_test.dart

@@ -0,0 +1,66 @@
+// Copyright (c) 2018, 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.
+
+@JS()
+library mock;
+
+import 'package:js/js.dart';
+import 'package:expect/minitest.dart';
+
+@JS('Node')
+class Node {}
+
+@JS('HTMLDocument')
+class Document extends Node {
+  external Element get body;
+}
+
+@JS()
+external get foo;
+
+@JS()
+external Document get document;
+
+@JS('Element')
+class Element extends Node {
+  external String get tagName;
+}
+
+class MockDocument implements Document {
+  final Element body = new MockElement();
+}
+
+class MockElement implements Element {
+  final tagName = 'MockBody';
+}
+
+void main() {
+  test('js', () {
+    var f = foo;
+    expect(f, isNull);
+
+    var doc = document;
+    expect(doc is Document, isTrue);
+    // Fails in dart2js
+    // expect(doc is! Element, isTrue);
+    expect(doc is Node, isTrue);
+
+    expect(doc is! MockDocument, isTrue);
+    expect(doc is! MockElement, isTrue);
+  });
+
+  test('mock', () {
+    var doc = new MockDocument();
+    expect(doc is Document, isTrue);
+    // Fails in dart2js
+    // expect(doc is! Element, isTrue);
+    expect(doc is Node, isTrue);
+
+    var body = doc.body;
+    // Fails in dart2js
+    // expect(body is! Document, isTrue);
+    expect(body is Element, isTrue);
+    expect(body is Node, isTrue);
+  });
+}

tests/lib_2/html/js_typed_interop_lazy_test.dart

@@ -41,6 +41,18 @@ abstract class Foo<T> {
   T get obj;
 }
 
+class Mock1LazyClass implements LazyClass {
+  noSuchMethod(Invocation i) => i.memberName == #a ? 42 : null;
+}
+
+class Mock2LazyClass implements LazyClass {
+  get a => 42;
+}
+
+class Other {
+  noSuchMethod(Invocation i) {}
+}
+
 // This class would cause compile time issues if JS classes are not properly lazy.
 class FooImpl extends Foo<LazyClass> {
   LazyClass get obj => new LazyClass(100);
@@ -83,6 +95,11 @@ main() {
     });
 
     test('create instance', () {
+      var anon = new AnonClass(a: 42);
+      // Until LazyClass is defined, fall back to Anon behavior.
+      expect(anon is LazyClass, isTrue); //# 01: ok
+      expect(new Object() is! LazyClass, isTrue);
+
       document.body.append(new ScriptElement()
         ..type = 'text/javascript'
         ..innerHtml = r"""
@@ -98,7 +115,6 @@ baz.LazyClass = function LazyClass(a) {
       expect(l is AnonClass, isTrue);
       expect((l as AnonClass) == l, isTrue);
       expect((l as AnonClass2) == l, isTrue);
-      var anon = new AnonClass(a: 42);
       expect(anon is! LazyClass, isTrue); //# 01: ok
       expect(anon is AnonClass, isTrue);
       expect(anon is AnonClass2, isTrue);
@@ -139,5 +155,20 @@ baz.LazyClass = function LazyClass(a) {
       expect(() => genericClassDynamic.add(42), throws); //# 01: ok
       genericClassDynamic.add(null);
     });
+
+    test('mocks', () {
+      var mock1 = new Mock1LazyClass();
+      expect(mock1 is LazyClass, isTrue);
+      expect(mock1 as LazyClass, equals(mock1));
+      expect(mock1.a, equals(42));
+
+      var mock2 = new Mock2LazyClass();
+      expect(mock2 is LazyClass, isTrue);
+      expect(mock2 as LazyClass, equals(mock2));
+      expect(mock2.a, equals(42));
+
+      Object other = new Other();
+      expect(other is LazyClass, isFalse);
+    });
   });
 }