fix(store): call metareducer with the user's config initial state

modules/store/spec/store.spec.ts

@@ -534,24 +534,44 @@ describe('ngRx Store', () => {
       expect(metaReducerSpy2).toHaveBeenCalled();
     });
 
-    it('should create a meta reducer for feature and call it with the expected reducer', () => {
+    it('should create a meta reducer for feature and call it with the expected reducer', done => {
+      const counterReducer2Spy = jasmine
+        .createSpy('counterReducer2Spy', counterReducer2)
+        .and.callThrough();
+
       TestBed.configureTestingModule({
         imports: [
           StoreModule.forRoot({}),
           StoreModule.forFeature('counter1', counterReducer, {
             metaReducers: [metaReducerContainer.metaReducer1],
           }),
-          StoreModule.forFeature('counter2', counterReducer2, {
-            metaReducers: [metaReducerContainer.metaReducer2],
-          }),
+          StoreModule.forFeature(
+            'counter2',
+            { counter: counterReducer2Spy },
+            {
+              initialState: { counter: 2 },
+              metaReducers: [metaReducerContainer.metaReducer2],
+            }
+          ),
         ],
       });
+
       const mockStore = TestBed.get(Store);
       const action = { type: INCREMENT };
+
       mockStore.dispatch(action);
 
       expect(metaReducerSpy1).toHaveBeenCalledWith(counterReducer);
-      expect(metaReducerSpy2).toHaveBeenCalledWith(counterReducer2);
+      expect(metaReducerSpy2).toHaveBeenCalled();
+      expect(counterReducer2Spy).toHaveBeenCalledWith(2, action);
+
+      mockStore.pipe(take(1)).subscribe({
+        next(val: any) {
+          expect(val['counter2'].counter).toEqual(3);
+        },
+        error: done,
+        complete: done,
+      });
     });
   });
 

modules/store/src/utils.ts

@@ -4,6 +4,7 @@ import {
   ActionReducerFactory,
   ActionReducerMap,
   MetaReducer,
+  InitialState,
 } from './models';
 
 export function combineReducers<T, V extends Action = Action>(
@@ -92,10 +93,17 @@ export function createReducerFactory<T, V extends Action = Action>(
   metaReducers?: MetaReducer<T, V>[]
 ): ActionReducerFactory<T, V> {
   if (Array.isArray(metaReducers) && metaReducers.length > 0) {
-    return compose.apply(null, [...metaReducers, reducerFactory]);
+    reducerFactory = compose.apply(null, [...metaReducers, reducerFactory]);
   }
 
-  return reducerFactory;
+  return (rm: ActionReducerMap<T, V>, initialState?: InitialState<T>) => {
+    const reducer = reducerFactory(rm, initialState);
+
+    return (state: T | undefined, action: V) => {
+      state = state === undefined ? (initialState as T) : state;
+      return typeof reducer === 'function' ? reducer(state, action) : state;
+    };
+  };
 }
 
 export function createFeatureReducerFactory<T, V extends Action = Action>(