gkalpak · Feb 15, 2019
diff --git a/packages/compiler-cli/src/ngtsc/annotations/src/directive.ts b/packages/compiler-cli/src/ngtsc/annotations/src/directive.ts
@@ -202,8 +202,7 @@ export function extractDirectiveMetadata(
   }
 
   // Detect if the component inherits from another class
-  const usesInheritance = clazz.heritageClauses !== undefined &&
-      clazz.heritageClauses.some(hc => hc.token === ts.SyntaxKind.ExtendsKeyword);
+  const usesInheritance = reflector.hasBaseClass(clazz);
   const metadata: R3DirectiveMetadata = {
     name: clazz.name !.text,
     deps: getValidConstructorDependencies(clazz, reflector, isCore), host,

diff --git a/packages/compiler-cli/src/ngtsc/annotations/test/directive_spec.ts b/packages/compiler-cli/src/ngtsc/annotations/test/directive_spec.ts
@@ -0,0 +1,80 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import * as ts from 'typescript';
+
+import {ReferenceEmitter} from '../../imports';
+import {PartialEvaluator} from '../../partial_evaluator';
+import {TypeScriptReflectionHost} from '../../reflection';
+import {getDeclaration, makeProgram} from '../../testing/in_memory_typescript';
+import {DirectiveDecoratorHandler} from '../src/directive';
+import {SelectorScopeRegistry} from '../src/selector_scope';
+
+
+describe('DirectiveDecoratorHandler', () => {
+  it('should use the `ReflectionHost` to detect class inheritance', () => {
+    const {program, options, host} = makeProgram([
+      {
+        name: 'node_modules/@angular/core/index.d.ts',
+        contents: 'export const Directive: any;',
+      },
+      {
+        name: 'entry.ts',
+        contents: `
+          import {Directive} from '@angular/core';
+
+          @Directive({selector: 'test-dir-1'})
+          export class TestDir1 {}
+
+          @Directive({selector: 'test-dir-2'})
+          export class TestDir2 {}
+        `,
+      },
+    ]);
+
+    const checker = program.getTypeChecker();
+    const reflectionHost = new TestReflectionHost(checker);
+    const evaluator = new PartialEvaluator(reflectionHost, checker);
+    const handler = new DirectiveDecoratorHandler(
+        reflectionHost, evaluator,
+        new SelectorScopeRegistry(checker, reflectionHost, new ReferenceEmitter([])), false);
+
+    const analyzeDirective = (dirName: string) => {
+      const DirNode = getDeclaration(program, 'entry.ts', dirName, ts.isClassDeclaration);
+
+      const detected = handler.detect(DirNode, reflectionHost.getDecoratorsOfDeclaration(DirNode));
+      if (detected === undefined) {
+        throw new Error(`Failed to recognize @Directive (${dirName}).`);
+      }
+
+      const {analysis} = handler.analyze(DirNode, detected.metadata);
+      if (analysis === undefined) {
+        throw new Error(`Failed to analyze @Directive (${dirName}).`);
+      }
+
+      return analysis;
+    };
+
+    // By default, `TestReflectionHost#hasBaseClass()` returns `false`.
+    const analysis1 = analyzeDirective('TestDir1');
+    expect(analysis1.meta.usesInheritance).toBe(false);
+
+    // Tweak `TestReflectionHost#hasBaseClass()` to return true.
+    reflectionHost.hasBaseClassReturnValue = true;
+
+    const analysis2 = analyzeDirective('TestDir2');
+    expect(analysis2.meta.usesInheritance).toBe(true);
+  });
+});
+
+// Helpers
+class TestReflectionHost extends TypeScriptReflectionHost {
+  hasBaseClassReturnValue = false;
+
+  hasBaseClass(node: ts.Declaration): boolean { return this.hasBaseClassReturnValue; }
+}