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

modules/store/spec/modules.spec.ts

@@ -95,14 +95,13 @@ describe(`Store Modules`, () => {
     });
 
     it(`should accept configurations`, () => {
-      expect(featureAReducerFactory).toHaveBeenCalledWith(
-        { a: featureAReducer },
-        featureAInitial()
-      );
-      expect(rootReducerFactory).toHaveBeenCalledWith(
-        { fruit: rootFruitReducer },
-        rootInitial
-      );
+      expect(featureAReducerFactory).toHaveBeenCalledWith({
+        a: featureAReducer,
+      });
+
+      expect(rootReducerFactory).toHaveBeenCalledWith({
+        fruit: rootFruitReducer,
+      });
     });
 
     it(`should should use config.reducerFactory`, () => {

modules/store/spec/store.spec.ts

@@ -14,6 +14,7 @@ import {
   Action,
 } from '../';
 import { StoreConfig } from '../src/store_module';
+import { combineReducers } from '../src/utils';
 import {
   counterReducer,
   INCREMENT,
@@ -373,11 +374,11 @@ describe('ngRx Store', () => {
     });
 
     it('should dispatch an update reducers action when a feature is added', () => {
-      reducerManager.addFeature(
-        createFeature({
-          key: 'feature1',
-        })
-      );
+      reducerManager.addFeature({
+        key: 'feature1',
+        reducers: {},
+        reducerFactory: <any>combineReducers,
+      });
 
       expect(reducerManagerDispatcherSpy).toHaveBeenCalledWith({
         type: UPDATE,
@@ -387,12 +388,16 @@ describe('ngRx Store', () => {
 
     it('should dispatch an update reducers action when multiple features are added', () => {
       reducerManager.addFeatures([
-        createFeature({
+        {
           key: 'feature1',
-        }),
-        createFeature({
+          reducers: {},
+          reducerFactory: <any>combineReducers,
+        },
+        {
           key: 'feature2',
-        }),
+          reducers: {},
+          reducerFactory: <any>combineReducers,
+        },
       ]);
 
       expect(reducerManagerDispatcherSpy).toHaveBeenCalledTimes(1);
@@ -546,13 +551,42 @@ describe('ngRx Store', () => {
           }),
         ],
       });
+
       const mockStore = TestBed.get(Store);
       const action = { type: INCREMENT };
+
       mockStore.dispatch(action);
 
       expect(metaReducerSpy1).toHaveBeenCalledWith(counterReducer);
       expect(metaReducerSpy2).toHaveBeenCalledWith(counterReducer2);
     });
+
+    it('should initial state with value', (done: DoneFn) => {
+      const counterInitialState = 2;
+      TestBed.configureTestingModule({
+        imports: [
+          StoreModule.forRoot({}),
+          StoreModule.forFeature(
+            'counterState',
+            { counter: counterReducer },
+            {
+              initialState: { counter: counterInitialState },
+              metaReducers: [metaReducerContainer.metaReducer1],
+            }
+          ),
+        ],
+      });
+
+      const mockStore = TestBed.get(Store);
+
+      mockStore.pipe(take(1)).subscribe({
+        next(val: any) {
+          expect(val['counterState'].counter).toEqual(counterInitialState);
+        },
+        error: done,
+        complete: done,
+      });
+    });
   });
 
   describe('Feature config token', () => {

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 +93,16 @@ 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 (reducers: ActionReducerMap<T, V>, initialState?: InitialState<T>) => {
+    const reducer = reducerFactory(reducers);
+    return (state: T | undefined, action: V) => {
+      state = state === undefined ? (initialState as T) : state;
+      return reducer(state, action);
+    };
+  };
 }
 
 export function createFeatureReducerFactory<T, V extends Action = Action>(