feat(Effects): Add getEffectsMetadata() helper for verifying metadata

Closes #491

docs/effects/testing.md

@@ -47,6 +47,46 @@ describe('My Effects', () => {
     effects.someSource$.subscribe(result => {
       expect(result).toEqual(AnotherAction);
     });
-  });  
+  });
+});
+```
+
+### getEffectsMetadata
+Returns decorator configuration for all effects in a class instance.
+Use this function to ensure that effects have been properly decorated.
+
+Usage:
+```ts
+import { TestBed } from '@angular/core/testing';
+import { EffectsMetadata, getEffectsMetadata } from '@ngrx/effects';
+import { MyEffects } from './my-effects';
+
+describe('My Effects', () => {
+  let effects: MyEffects;
+  let metadata: EffectsMetadata<MyEffects>;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({
+      providers: [
+        MyEffects,
+        // other providers
+      ],
+    });
+
+    effects = TestBed.get(MyEffects);
+    metadata = getEffectsMetadata(effects);
+  });
+
+  it('should register someSource$ that dispatches an action', () => {
+    expect(metadata.someSource$).toEqual({ dispatch: true });
+  });
+
+  it('should register someOtherSource$ that does not dispatch an action', () => {
+    expect(metadata.someOtherSource$).toEqual({ dispatch: false });
+  });
+
+  it('should not register undecoratedSource$', () => {
+    expect(metadata.undecoratedSource$).toBeUndefined();
+  });
 });
 ```

modules/effects/spec/effects_metadata.spec.ts

@@ -1,5 +1,6 @@
 import {
   Effect,
+  getEffectsMetadata,
   getSourceMetadata,
   getSourceForInstance,
 } from '../src/effects_metadata';
@@ -46,4 +47,36 @@ describe('Effect Metadata', () => {
       expect(proto).toBe(Fixture.prototype);
     });
   });
+
+  describe('getEffectsMetadata', () => {
+    it('should get map of metadata for all decorated effects in a class instance', () => {
+      class Fixture {
+        @Effect() a: any;
+        @Effect({ dispatch: true })
+        b: any;
+        @Effect({ dispatch: false })
+        c: any;
+      }
+
+      const mock = new Fixture();
+
+      expect(getEffectsMetadata(mock)).toEqual({
+        a: { dispatch: true },
+        b: { dispatch: true },
+        c: { dispatch: false },
+      });
+    });
+
+    it('should return an empty map if the class has not been decorated', () => {
+      class Fixture {
+        a: any;
+        b: any;
+        c: any;
+      }
+
+      const mock = new Fixture();
+
+      expect(getEffectsMetadata(mock)).toEqual({});
+    });
+  });
 });

modules/effects/src/effects_metadata.ts

@@ -40,3 +40,21 @@ export const getSourceMetadata = compose(
   getEffectMetadataEntries,
   getSourceForInstance
 );
+
+export type EffectsMetadata<T> = {
+  [key in keyof T]?:
+    | undefined
+    | {
+        dispatch: boolean;
+      }
+};
+
+export function getEffectsMetadata<T>(instance: T): EffectsMetadata<T> {
+  const metadata: EffectsMetadata<T> = {};
+
+  getSourceMetadata(instance).forEach(({ propertyName, dispatch }) => {
+    metadata[propertyName] = { dispatch };
+  });
+
+  return metadata;
+}

modules/effects/src/index.ts

@@ -1,4 +1,8 @@
-export { Effect } from './effects_metadata';
+export {
+  Effect,
+  EffectsMetadata,
+  getEffectsMetadata,
+} from './effects_metadata';
 export { mergeEffects } from './effects_resolver';
 export { Actions } from './actions';
 export { EffectsModule } from './effects_module';