feat: memoize function by arg

help-me-mom · Feb 3, 2018 · 031e3a6 · 031e3a6
1 parent 155ade2
commit 031e3a6
Show file tree

Hide file tree

Showing 2 changed files with 20 additions and 6 deletions.
diff --git a/lib/mock_directive.spec.ts b/lib/mock_directive.spec.ts
@@ -27,7 +27,6 @@ export class ExampleComponentContainer {}
 
 describe('MockComponent', () => {
   let fixture: ComponentFixture<ExampleComponentContainer>;
-  let directive: Type<ExampleDirective>;
 
   getTestBed().initTestEnvironment(
     BrowserDynamicTestingModule,
@@ -38,7 +37,7 @@ describe('MockComponent', () => {
     TestBed.configureTestingModule({
       declarations: [
         ExampleComponentContainer,
-        directive = MockDirective(ExampleDirective)
+        MockDirective(ExampleDirective)
       ]
     })
     .compileComponents();
@@ -50,14 +49,19 @@ describe('MockComponent', () => {
   });
 
   it('should have use the original component\'s selector', () => {
-    const element = fixture.debugElement.query(By.directive(directive));
+    const element = fixture.debugElement.query(By.directive(MockDirective(ExampleDirective)));
     expect(element).not.toBeNull();
   });
 
   it('should have the input set on the mock component', () => {
-    const debugElement = fixture.debugElement.query(By.directive(directive));
-    const element = debugElement.injector.get(directive);
+    const debugElement = fixture.debugElement.query(By.directive(MockDirective(ExampleDirective)));
+    const element = debugElement.injector.get(MockDirective(ExampleDirective));
     expect(element.something).toEqual('hi');
     expect(element.exampleDirective).toEqual('bye');
   });
+
+  it('should memoize the return value by argument', () => {
+    expect(MockDirective(ExampleDirective)).toEqual(MockDirective(ExampleDirective));
+    expect(MockDirective(ExampleDirective)).not.toEqual(ExampleDirective);
+  });
 });
diff --git a/lib/mock_directive.ts b/lib/mock_directive.ts
@@ -1,6 +1,13 @@
 import { Directive, Type } from '@angular/core';
 
+const cache = new Map<Type<Directive>, Type<Directive>>();
+
 export function MockDirective<TDirective>(directive: Type<TDirective>): Type<TDirective> {
+  const cacheHit = cache.get(directive);
+  if (cacheHit) {
+    return cacheHit as Type<TDirective>;
+  }
+
   const annotations = (directive as any).__annotations__[0] || {};
   const propertyMetadata = (directive as any).__prop__metadata__ || {};
 
@@ -12,7 +19,10 @@ export function MockDirective<TDirective>(directive: Type<TDirective>): Type<TDi
     selector: annotations.selector
   };
 
-  return Directive(options)(class DirectiveMock {} as Type<TDirective>);
+  const mockedDirective =  Directive(options)(class DirectiveMock {} as Type<TDirective>);
+  cache.set(directive, mockedDirective);
+
+  return mockedDirective;
 }
 
 function isInput(propertyMetadata: any): boolean {