Reorganize equivalence test helpers

tests/compiler/dart2js/equivalence/check_functions.dart

Index: tests/compiler/dart2js/equivalence/check_functions.dart
diff --git a/tests/compiler/dart2js/equivalence/check_functions.dart b/tests/compiler/dart2js/equivalence/check_functions.dart
new file mode 100644
index 0000000000000000000000000000000000000000..4f82bde0ff62a82929215ac5616a924934a7047a
--- /dev/null
+++ b/tests/compiler/dart2js/equivalence/check_functions.dart
@@ -0,0 +1,612 @@
+// Copyright (c) 2017, 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.
+
+/// Equivalence test functions for data objects.
+
+library dart2js.equivalence.functions;
+
+import 'package:expect/expect.dart';
+import 'package:compiler/src/common/resolution.dart';
+import 'package:compiler/src/common_elements.dart';
+import 'package:compiler/src/compiler.dart';
+import 'package:compiler/src/elements/types.dart';
+import 'package:compiler/src/elements/elements.dart';
+import 'package:compiler/src/elements/entities.dart';
+import 'package:compiler/src/enqueue.dart';
+import 'package:compiler/src/js_backend/backend_usage.dart';
+import 'package:compiler/src/js_backend/native_data.dart';
+import 'package:compiler/src/js_backend/interceptor_data.dart';
+import 'package:compiler/src/serialization/equivalence.dart';
+import 'package:compiler/src/universe/class_set.dart';
+import 'package:compiler/src/universe/world_builder.dart';
+import 'package:compiler/src/world.dart';
+import 'check_helpers.dart';
+
+void checkClosedWorlds(ClosedWorld closedWorld1, ClosedWorld closedWorld2,
+    {TestStrategy strategy: const TestStrategy(),
+    bool allowExtra: false,
+    bool verbose: false}) {
+  if (verbose) {
+    print(closedWorld1.dump());
+    print(closedWorld2.dump());
+  }
+  checkClassHierarchyNodes(
+      closedWorld1,
+      closedWorld2,
+      closedWorld1
+          .getClassHierarchyNode(closedWorld1.commonElements.objectClass),
+      closedWorld2
+          .getClassHierarchyNode(closedWorld2.commonElements.objectClass),
+      strategy.elementEquivalence,
+      verbose: verbose);
+
+  checkNativeData(closedWorld1.nativeData, closedWorld2.nativeData,
+      strategy: strategy, allowExtra: allowExtra, verbose: verbose);
+  checkInterceptorData(closedWorld1.interceptorData,
+      closedWorld2.interceptorData, strategy.elementEquivalence,
+      verbose: verbose);
+}
+
+void checkNativeData(NativeDataImpl data1, NativeDataImpl data2,
+    {TestStrategy strategy: const TestStrategy(),
+    bool allowExtra: false,
+    bool verbose: false}) {
+  checkMapEquivalence(data1, data2, 'nativeMemberName', data1.nativeMemberName,
+      data2.nativeMemberName, strategy.elementEquivalence, equality,
+      allowExtra: allowExtra);
+
+  checkMapEquivalence(
+      data1,
+      data2,
+      'nativeMethodBehavior',
+      data1.nativeMethodBehavior,
+      data2.nativeMethodBehavior,
+      strategy.elementEquivalence,
+      (a, b) => testNativeBehavior(a, b, strategy: strategy),
+      allowExtra: allowExtra);
+
+  checkMapEquivalence(
+      data1,
+      data2,
+      'nativeFieldLoadBehavior',
+      data1.nativeFieldLoadBehavior,
+      data2.nativeFieldLoadBehavior,
+      strategy.elementEquivalence,
+      (a, b) => testNativeBehavior(a, b, strategy: strategy),
+      allowExtra: allowExtra);
+
+  checkMapEquivalence(
+      data1,
+      data2,
+      'nativeFieldStoreBehavior',
+      data1.nativeFieldStoreBehavior,
+      data2.nativeFieldStoreBehavior,
+      strategy.elementEquivalence,
+      (a, b) => testNativeBehavior(a, b, strategy: strategy),
+      allowExtra: allowExtra);
+
+  checkMapEquivalence(
+      data1,
+      data2,
+      'jsInteropLibraryNames',
+      data1.jsInteropLibraryNames,
+      data2.jsInteropLibraryNames,
+      strategy.elementEquivalence,
+      equality);
+
+  checkSetEquivalence(
+      data1,
+      data2,
+      'anonymousJsInteropClasses',
+      data1.anonymousJsInteropClasses,
+      data2.anonymousJsInteropClasses,
+      strategy.elementEquivalence);
+
+  checkMapEquivalence(
+      data1,
+      data2,
+      'jsInteropClassNames',
+      data1.jsInteropClassNames,
+      data2.jsInteropClassNames,
+      strategy.elementEquivalence,
+      equality);
+
+  checkMapEquivalence(
+      data1,
+      data2,
+      'jsInteropMemberNames',
+      data1.jsInteropMemberNames,
+      data2.jsInteropMemberNames,
+      strategy.elementEquivalence,
+      equality);
+}
+
+void checkInterceptorData(InterceptorDataImpl data1, InterceptorDataImpl data2,
+    bool elementEquivalence(Entity a, Entity b),
+    {bool verbose: false}) {
+  checkMapEquivalence(
+      data1,
+      data2,
+      'interceptedElements',
+      data1.interceptedElementsForTesting,
+      data2.interceptedElementsForTesting,
+      equality,
+      (a, b) => areSetsEquivalent(a, b, elementEquivalence));
+
+  checkSetEquivalence(data1, data2, 'interceptedClasses',
+      data1.interceptedClasses, data2.interceptedClasses, elementEquivalence);
+
+  checkSetEquivalence(
+      data1,
+      data2,
+      'classesMixedIntoInterceptedClasses',
+      data1.classesMixedIntoInterceptedClassesForTesting,
+      data2.classesMixedIntoInterceptedClassesForTesting,
+      elementEquivalence);
+}
+
+void checkClassHierarchyNodes(
+    ClosedWorld closedWorld1,
+    ClosedWorld closedWorld2,
+    ClassHierarchyNode node1,
+    ClassHierarchyNode node2,
+    bool elementEquivalence(Entity a, Entity b),
+    {bool verbose: false}) {
+  if (verbose) {
+    print('Checking $node1 vs $node2');
+  }
+  ClassEntity cls1 = node1.cls;
+  ClassEntity cls2 = node2.cls;
+  Expect.isTrue(elementEquivalence(cls1, cls2),
+      "Element identity mismatch for ${cls1} vs ${cls2}.");
+  Expect.equals(
+      node1.isDirectlyInstantiated,
+      node2.isDirectlyInstantiated,
+      "Value mismatch for 'isDirectlyInstantiated' "
+      "for ${cls1} vs ${cls2}.");
+  Expect.equals(
+      node1.isIndirectlyInstantiated,
+      node2.isIndirectlyInstantiated,
+      "Value mismatch for 'isIndirectlyInstantiated' "
+      "for ${node1.cls} vs ${node2.cls}.");
+  // TODO(johnniwinther): Enforce a canonical and stable order on direct
+  // subclasses.
+  for (ClassHierarchyNode child in node1.directSubclasses) {
+    bool found = false;
+    for (ClassHierarchyNode other in node2.directSubclasses) {
+      ClassEntity child1 = child.cls;
+      ClassEntity child2 = other.cls;
+      if (elementEquivalence(child1, child2)) {
+        checkClassHierarchyNodes(
+            closedWorld1, closedWorld2, child, other, elementEquivalence,
+            verbose: verbose);
+        found = true;
+        break;
+      }
+    }
+    if (!found) {
+      if (child.isInstantiated) {
+        print('Missing subclass ${child.cls} of ${node1.cls} '
+            'in ${node2.directSubclasses}');
+        print(closedWorld1.dump(
+            verbose ? closedWorld1.commonElements.objectClass : node1.cls));
+        print(closedWorld2.dump(
+            verbose ? closedWorld2.commonElements.objectClass : node2.cls));
+      }
+      Expect.isFalse(
+          child.isInstantiated,
+          'Missing subclass ${child.cls} of ${node1.cls} in '
+          '${node2.directSubclasses}');
+    }
+  }
+  checkMixinUses(
+      closedWorld1, closedWorld2, node1.cls, node2.cls, elementEquivalence,
+      verbose: verbose);
+}
+
+void checkMixinUses(
+    ClosedWorld closedWorld1,
+    ClosedWorld closedWorld2,
+    ClassEntity class1,
+    ClassEntity class2,
+    bool elementEquivalence(Entity a, Entity b),
+    {bool verbose: false}) {
+  checkSets(closedWorld1.mixinUsesOf(class1), closedWorld2.mixinUsesOf(class2),
+      "Mixin uses of $class1 vs $class2", elementEquivalence,
+      verbose: verbose);
+}
+
+/// Check member property equivalence between all members common to [compiler1]
+/// and [compiler2].
+void checkLoadedLibraryMembers(
+    Compiler compiler1,
+    Compiler compiler2,
+    bool hasProperty(Element member1),
+    void checkMemberProperties(Compiler compiler1, Element member1,
+        Compiler compiler2, Element member2,
+        {bool verbose}),
+    {bool verbose: false}) {
+  void checkMembers(Element member1, Element member2) {
+    if (member1.isClass && member2.isClass) {
+      ClassElement class1 = member1;
+      ClassElement class2 = member2;
+      if (!class1.isResolved) return;
+
+      if (hasProperty(member1)) {
+        if (areElementsEquivalent(member1, member2)) {
+          checkMemberProperties(compiler1, member1, compiler2, member2,
+              verbose: verbose);
+        }
+      }
+
+      class1.forEachLocalMember((m1) {
+        checkMembers(m1, class2.localLookup(m1.name));
+      });
+      ClassElement superclass1 = class1.superclass;
+      ClassElement superclass2 = class2.superclass;
+      while (superclass1 != null && superclass1.isUnnamedMixinApplication) {
+        for (ConstructorElement c1 in superclass1.constructors) {
+          checkMembers(c1, superclass2.lookupConstructor(c1.name));
+        }
+        superclass1 = superclass1.superclass;
+        superclass2 = superclass2.superclass;
+      }
+      return;
+    }
+
+    if (!hasProperty(member1)) {
+      return;
+    }
+
+    if (member2 == null) {
+      throw 'Missing member for ${member1}';
+    }
+
+    if (areElementsEquivalent(member1, member2)) {
+      checkMemberProperties(compiler1, member1, compiler2, member2,
+          verbose: verbose);
+    }
+  }
+
+  for (LibraryElement library1 in compiler1.libraryLoader.libraries) {
+    LibraryElement library2 =
+        compiler2.libraryLoader.lookupLibrary(library1.canonicalUri);
+    if (library2 != null) {
+      library1.forEachLocalMember((Element member1) {
+        checkMembers(member1, library2.localLookup(member1.name));
+      });
+    }
+  }
+}
+
+/// Check equivalence of all resolution impacts.
+void checkAllImpacts(Compiler compiler1, Compiler compiler2,
+    {bool verbose: false}) {
+  checkLoadedLibraryMembers(compiler1, compiler2, (Element member1) {
+    return compiler1.resolution.hasResolutionImpact(member1);
+  }, checkImpacts, verbose: verbose);
+}
+
+/// Check equivalence of resolution impact for [member1] and [member2].
+void checkImpacts(
+    Compiler compiler1, Element member1, Compiler compiler2, Element member2,
+    {bool verbose: false}) {
+  ResolutionImpact impact1 = compiler1.resolution.getResolutionImpact(member1);
+  ResolutionImpact impact2 = compiler2.resolution.getResolutionImpact(member2);
+
+  if (impact1 == null && impact2 == null) return;
+
+  if (verbose) {
+    print('Checking impacts for $member1 vs $member2');
+  }
+
+  if (impact1 == null) {
+    throw 'Missing impact for $member1. $member2 has $impact2';
+  }
+  if (impact2 == null) {
+    throw 'Missing impact for $member2. $member1 has $impact1';
+  }
+
+  testResolutionImpactEquivalence(impact1, impact2,
+      strategy: const CheckStrategy());
+}
+
+void checkAllResolvedAsts(Compiler compiler1, Compiler compiler2,
+    {bool verbose: false}) {
+  checkLoadedLibraryMembers(compiler1, compiler2, (Element member1) {
+    return member1 is ExecutableElement &&
+        compiler1.resolution.hasResolvedAst(member1);
+  }, checkResolvedAsts, verbose: verbose);
+}
+
+/// Check equivalence of [impact1] and [impact2].
+void checkResolvedAsts(
+    Compiler compiler1, Element member1, Compiler compiler2, Element member2,
+    {bool verbose: false}) {
+  if (!compiler2.serialization.isDeserialized(member2)) {
+    return;
+  }
+  ResolvedAst resolvedAst1 = compiler1.resolution.getResolvedAst(member1);
+  ResolvedAst resolvedAst2 = compiler2.serialization.getResolvedAst(member2);
+
+  if (resolvedAst1 == null || resolvedAst2 == null) return;
+
+  if (verbose) {
+    print('Checking resolved asts for $member1 vs $member2');
+  }
+
+  testResolvedAstEquivalence(resolvedAst1, resolvedAst2, const CheckStrategy());
+}
+
+void checkNativeClasses(
+    Compiler compiler1, Compiler compiler2, TestStrategy strategy) {
+  Iterable<ClassEntity> nativeClasses1 = compiler1
+      .backend.nativeResolutionEnqueuerForTesting.nativeClassesForTesting;
+  Iterable<ClassEntity> nativeClasses2 = compiler2
+      .backend.nativeResolutionEnqueuerForTesting.nativeClassesForTesting;
+
+  checkSetEquivalence(compiler1, compiler2, 'nativeClasses', nativeClasses1,
+      nativeClasses2, strategy.elementEquivalence);
+
+  Iterable<ClassEntity> registeredClasses1 = compiler1
+      .backend.nativeResolutionEnqueuerForTesting.registeredClassesForTesting;
+  Iterable<ClassEntity> registeredClasses2 = compiler2
+      .backend.nativeResolutionEnqueuerForTesting.registeredClassesForTesting;
+
+  checkSetEquivalence(compiler1, compiler2, 'registeredClasses',
+      registeredClasses1, registeredClasses2, strategy.elementEquivalence);
+}
+
+void checkNativeBasicData(NativeBasicDataImpl data1, NativeBasicDataImpl data2,
+    TestStrategy strategy) {
+  checkMapEquivalence(
+      data1,
+      data2,
+      'nativeClassTagInfo',
+      data1.nativeClassTagInfo,
+      data2.nativeClassTagInfo,
+      strategy.elementEquivalence,
+      (a, b) => a == b);
+  // TODO(johnniwinther): Check the remaining properties.
+}
+
+void checkBackendUsage(
+    BackendUsageImpl usage1, BackendUsageImpl usage2, TestStrategy strategy) {
+  checkSetEquivalence(
+      usage1,
+      usage2,
+      'globalClassDependencies',
+      usage1.globalClassDependencies,
+      usage2.globalClassDependencies,
+      strategy.elementEquivalence);
+  checkSetEquivalence(
+      usage1,
+      usage2,
+      'globalFunctionDependencies',
+      usage1.globalFunctionDependencies,
+      usage2.globalFunctionDependencies,
+      strategy.elementEquivalence);
+  checkSetEquivalence(
+      usage1,
+      usage2,
+      'helperClassesUsed',
+      usage1.helperClassesUsed,
+      usage2.helperClassesUsed,
+      strategy.elementEquivalence);
+  checkSetEquivalence(
+      usage1,
+      usage2,
+      'helperFunctionsUsed',
+      usage1.helperFunctionsUsed,
+      usage2.helperFunctionsUsed,
+      strategy.elementEquivalence);
+  check(
+      usage1,
+      usage2,
+      'needToInitializeIsolateAffinityTag',
+      usage1.needToInitializeIsolateAffinityTag,
+      usage2.needToInitializeIsolateAffinityTag);
+  check(
+      usage1,
+      usage2,
+      'needToInitializeDispatchProperty',
+      usage1.needToInitializeDispatchProperty,
+      usage2.needToInitializeDispatchProperty);
+  check(usage1, usage2, 'requiresPreamble', usage1.requiresPreamble,
+      usage2.requiresPreamble);
+  check(usage1, usage2, 'isInvokeOnUsed', usage1.isInvokeOnUsed,
+      usage2.isInvokeOnUsed);
+  check(usage1, usage2, 'isRuntimeTypeUsed', usage1.isRuntimeTypeUsed,
+      usage2.isRuntimeTypeUsed);
+  check(usage1, usage2, 'isIsolateInUse', usage1.isIsolateInUse,
+      usage2.isIsolateInUse);
+  check(usage1, usage2, 'isFunctionApplyUsed', usage1.isFunctionApplyUsed,
+      usage2.isFunctionApplyUsed);
+  check(usage1, usage2, 'isNoSuchMethodUsed', usage1.isNoSuchMethodUsed,
+      usage2.isNoSuchMethodUsed);
+}
+
+checkElementEnvironment(
+    ElementEnvironment env1, ElementEnvironment env2, TestStrategy strategy) {
+  checkMembers(MemberEntity member1, MemberEntity member2) {
+    Expect.equals(env1.isDeferredLoadLibraryGetter(member1),
+        env2.isDeferredLoadLibraryGetter(member2));
+
+    checkListEquivalence(
+        member1,
+        member2,
+        'metadata',
+        env1.getMemberMetadata(member1),
+        env2.getMemberMetadata(member2),
+        strategy.testConstantValues);
+  }
+
+  checkSetEquivalence(env1, env2, 'libraries', env1.libraries, env2.libraries,
+      strategy.elementEquivalence,
+      onSameElement: (LibraryEntity lib1, LibraryEntity lib2) {
+    Expect.identical(lib1, env1.lookupLibrary(lib1.canonicalUri));
+    Expect.identical(lib2, env2.lookupLibrary(lib2.canonicalUri));
+
+    List<ClassEntity> classes2 = <ClassEntity>[];
+    env1.forEachClass(lib1, (ClassEntity cls1) {
+      Expect.identical(cls1, env1.lookupClass(lib1, cls1.name));
+
+      String className = cls1.name;
+      ClassEntity cls2 = env2.lookupClass(lib2, className);
+      Expect.isNotNull(cls2, 'Missing class $className in $lib2');
+      Expect.identical(cls2, env2.lookupClass(lib2, cls2.name));
+
+      check(lib1, lib2, 'class:${className}', cls1, cls2,
+          strategy.elementEquivalence);
+
+      Expect.equals(env1.isGenericClass(cls1), env2.isGenericClass(cls2));
+
+      check(
+          cls1,
+          cls2,
+          'superclass',
+          env1.getSuperClass(cls1, skipUnnamedMixinApplications: false),
+          env2.getSuperClass(cls2, skipUnnamedMixinApplications: false),
+          strategy.elementEquivalence);
+      check(
+          cls1,
+          cls2,
+          'superclass',
+          env1.getSuperClass(cls1, skipUnnamedMixinApplications: true),
+          env2.getSuperClass(cls2, skipUnnamedMixinApplications: true),
+          strategy.elementEquivalence);
+
+      List<InterfaceType> supertypes1 = <InterfaceType>[];
+      env1.forEachSupertype(cls1, supertypes1.add);
+      List<InterfaceType> supertypes2 = <InterfaceType>[];
+      env2.forEachSupertype(cls2, supertypes1.add);
+      strategy.testTypeLists(
+          cls1, cls2, 'supertypes', supertypes1, supertypes2);
+
+      List<ClassEntity> mixins1 = <ClassEntity>[];
+      env1.forEachMixin(cls1, mixins1.add);
+      List<ClassEntity> mixins2 = <ClassEntity>[];
+      env2.forEachMixin(cls2, mixins2.add);
+      strategy.testLists(
+          cls1, cls2, 'mixins', mixins1, mixins2, strategy.elementEquivalence);
+
+      Map<MemberEntity, ClassEntity> members1 = <MemberEntity, ClassEntity>{};
+      Map<MemberEntity, ClassEntity> members2 = <MemberEntity, ClassEntity>{};
+      env1.forEachClassMember(cls1,
+          (ClassEntity declarer1, MemberEntity member1) {
+        if (cls1 == declarer1) {
+          Expect.identical(
+              member1,
+              env1.lookupClassMember(cls1, member1.name,
+                  setter: member1.isSetter));
+        }
+        members1[member1] = declarer1;
+      });
+      env2.forEachClassMember(cls2,
+          (ClassEntity declarer2, MemberEntity member2) {
+        if (cls2 == declarer2) {
+          Expect.identical(
+              member2,
+              env2.lookupClassMember(cls2, member2.name,
+                  setter: member2.isSetter));
+        }
+        members2[member2] = declarer2;
+      });
+      checkMapEquivalence(cls1, cls2, 'members', members1, members2, (a, b) {
+        bool result = strategy.elementEquivalence(a, b);
+        if (result) checkMembers(a, b);
+        return result;
+      }, strategy.elementEquivalence);
+
+      classes2.add(cls2);
+    });
+    env2.forEachClass(lib2, (ClassEntity cls2) {
+      Expect.isTrue(classes2.contains(cls2), "Extra class $cls2 in $lib2");
+    });
+  });
+  // TODO(johnniwinther): Test the remaining properties of [ElementEnvironment].
+}
+
+bool areInstantiationInfosEquivalent(
+    InstantiationInfo info1,
+    InstantiationInfo info2,
+    bool elementEquivalence(Entity a, Entity b),
+    bool typeEquivalence(DartType a, DartType b)) {
+  checkMaps(
+      info1.instantiationMap,
+      info2.instantiationMap,
+      'instantiationMap of\n   '
+      '${info1.instantiationMap}\nvs ${info2.instantiationMap}',
+      elementEquivalence,
+      (a, b) => areSetsEquivalent(
+          a, b, (a, b) => areInstancesEquivalent(a, b, typeEquivalence)));
+  return true;
+}
+
+bool areInstancesEquivalent(Instance instance1, Instance instance2,
+    bool typeEquivalence(DartType a, DartType b)) {
+  InterfaceType type1 = instance1.type;
+  InterfaceType type2 = instance2.type;
+  return typeEquivalence(type1, type2) &&
+      instance1.kind == instance2.kind &&
+      instance1.isRedirection == instance2.isRedirection;
+}
+
+void checkResolutionEnqueuers(
+    BackendUsage backendUsage1,
+    BackendUsage backendUsage2,
+    ResolutionEnqueuer enqueuer1,
+    ResolutionEnqueuer enqueuer2,
+    {bool elementEquivalence(Entity a, Entity b): areElementsEquivalent,
+    bool typeEquivalence(DartType a, DartType b): areTypesEquivalent,
+    bool elementFilter(Element element),
+    bool verbose: false}) {
+  ResolutionWorldBuilderBase worldBuilder1 = enqueuer1.worldBuilder;
+  ResolutionWorldBuilderBase worldBuilder2 = enqueuer2.worldBuilder;
+
+  checkSets(
+      enqueuer1.worldBuilder.instantiatedTypes,
+      enqueuer2.worldBuilder.instantiatedTypes,
+      "Instantiated types mismatch",
+      typeEquivalence,
+      verbose: verbose);
+
+  checkSets(
+      enqueuer1.worldBuilder.directlyInstantiatedClasses,
+      enqueuer2.worldBuilder.directlyInstantiatedClasses,
+      "Directly instantiated classes mismatch",
+      elementEquivalence,
+      verbose: verbose);
+
+  checkMaps(
+      worldBuilder1.getInstantiationMap(),
+      worldBuilder2.getInstantiationMap(),
+      "Instantiated classes mismatch",
+      elementEquivalence,
+      (a, b) => areInstantiationInfosEquivalent(
+          a, b, elementEquivalence, typeEquivalence),
+      verbose: verbose);
+
+  checkSets(enqueuer1.processedEntities, enqueuer2.processedEntities,
+      "Processed element mismatch", elementEquivalence, elementFilter: (e) {
+    return elementFilter != null ? elementFilter(e) : true;
+  }, verbose: verbose);
+
+  checkSets(enqueuer1.worldBuilder.isChecks, enqueuer2.worldBuilder.isChecks,
+      "Is-check mismatch", typeEquivalence,
+      verbose: verbose);
+
+  Expect.equals(backendUsage1.isInvokeOnUsed, backendUsage2.isInvokeOnUsed,
+      "JavaScriptBackend.hasInvokeOnSupport mismatch");
+  Expect.equals(
+      backendUsage1.isFunctionApplyUsed,
+      backendUsage1.isFunctionApplyUsed,
+      "JavaScriptBackend.hasFunctionApplySupport mismatch");
+  Expect.equals(
+      backendUsage1.isRuntimeTypeUsed,
+      backendUsage2.isRuntimeTypeUsed,
+      "JavaScriptBackend.hasRuntimeTypeSupport mismatch");
+  Expect.equals(backendUsage1.isIsolateInUse, backendUsage2.isIsolateInUse,
+      "JavaScriptBackend.hasIsolateSupport mismatch");
+}