feat(store): add testing package (#1027)

Introduces `@ngrx/store/testing` that provides a mock store for using in test setup

Closes #915 

```ts
import { Store } from '@ngrx/store';
import { provideMockStore, MockStore } from '@ngrx/store/testing';
import { take } from 'rxjs/operators';

describe('Mock Store', () => {
  let mockStore: MockStore<{ counter1: number, counter2: number }>;

  beforeEach(() => {
    const initialState = { counter1: 0, counter2: 1 };

    TestBed.configureTestingModule({
      providers: [provideMockStore({ initialState })],
    });

    mockStore = TestBed.get(Store);
  });

  it('should set the new state', () => {
    mockStore.setState({ counter1: 1, counter2: 2 });

    mockStore.pipe(take(1)).subscribe(state => {
      expect(state.counter1).toBe(1);
    });
  });
});
```

Author: TeoTN

modules/store/BUILD

@@ -16,6 +16,7 @@ ng_package(
     name = "npm_package",
     srcs = glob(["**/*.externs.js"]) + [
         "package.json",
+        "//modules/store/testing:package.json",
     ],
     entry_point = "modules/store/index.js",
     packages = [
@@ -25,5 +26,6 @@ ng_package(
     ],
     deps = [
         ":store",
+        "//modules/store/testing",
     ],
 )

modules/store/spec/BUILD

@@ -10,6 +10,7 @@ ts_test_library(
     ),
     deps = [
         "//modules/store",
+        "//modules/store/testing",
         "@rxjs",
         "@rxjs//operators",
     ],

modules/store/spec/store.spec.ts

@@ -19,7 +19,8 @@ import {
 } from './fixtures/counter';
 import Spy = jasmine.Spy;
 import any = jasmine.any;
-import { take } from 'rxjs/operators';
+import { skip, take } from 'rxjs/operators';
+import { MockStore, provideMockStore } from '../testing';
 
 interface TestAppSchema {
   counter1: number;
@@ -432,4 +433,42 @@ describe('ngRx Store', () => {
       };
     }
   });
+
+  describe('Mock Store', () => {
+    let mockStore: MockStore<TestAppSchema>;
+
+    beforeEach(() => {
+      const initialState = { counter1: 0, counter2: 1 };
+
+      TestBed.configureTestingModule({
+        providers: [provideMockStore({ initialState })],
+      });
+
+      mockStore = TestBed.get(Store);
+    });
+
+    it('should set the initial state to a mocked one', (done: DoneFn) => {
+      const fixedState = {
+        counter1: 17,
+        counter2: 11,
+        counter3: 25,
+      };
+      mockStore.setState(fixedState);
+      mockStore.pipe(take(1)).subscribe({
+        next(val) {
+          expect(val).toEqual(fixedState);
+        },
+        error: done.fail,
+        complete: done,
+      });
+    });
+
+    it('should allow tracing dispatched actions', () => {
+      const action = { type: INCREMENT };
+      mockStore.scannedActions$
+        .pipe(skip(1))
+        .subscribe(scannedAction => expect(scannedAction).toEqual(action));
+      mockStore.dispatch(action);
+    });
+  });
 });

modules/store/testing/BUILD

@@ -0,0 +1,19 @@
+package(default_visibility = ["//visibility:public"])
+
+exports_files(["package.json"])
+
+load("//tools:defaults.bzl", "ng_module")
+
+ng_module(
+    name = "testing",
+    srcs = glob([
+        "*.ts",
+        "src/**/*.ts",
+    ]),
+    module_name = "@ngrx/store/testing",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//modules/store",
+        "@rxjs",
+    ],
+)

modules/store/testing/index.ts

@@ -0,0 +1 @@
+export * from './src/testing';

modules/store/testing/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "@ngrx/store/testing",
+  "typings": "./testing.d.ts",
+  "main": "../bundles/core-testing.umd.js",
+  "module": "../fesm5/testing.js",
+  "es2015": "../fesm2015/testing.js",
+  "esm5": "../esm5/testing/testing.js",
+  "esm2015": "../esm2015/testing/testing.js",
+  "fesm5": "../fesm5/testing.js",
+  "fesm2015": "../fesm2015/testing.js"
+}

modules/store/testing/rollup.config.js

@@ -0,0 +1,12 @@
+export default {
+  entry: './dist/store/@ngrx/store/testing.es5.js',
+  dest: './dist/store/bundles/store-testing.umd.js',
+  format: 'umd',
+  exports: 'named',
+  moduleName: 'ngrx.store.testing',
+  globals: {
+    '@angular/core': 'ng.core',
+    '@ngrx/store': 'ngrx.store',
+    'rxjs': 'Rx',
+  }
+}

modules/store/testing/src/mock_reducer_manager.ts

@@ -0,0 +1,12 @@
+import { Injectable } from '@angular/core';
+import { BehaviorSubject } from 'rxjs';
+import { ActionReducer } from '@ngrx/store';
+
+@Injectable()
+export class MockReducerManager extends BehaviorSubject<
+  ActionReducer<any, any>
+> {
+  constructor() {
+    super(() => undefined);
+  }
+}

modules/store/testing/src/mock_state.ts

@@ -0,0 +1,9 @@
+import { Injectable } from '@angular/core';
+import { BehaviorSubject } from 'rxjs';
+
+@Injectable()
+export class MockState<T extends {}> extends BehaviorSubject<T> {
+  constructor() {
+    super(<T>{});
+  }
+}

modules/store/testing/src/mock_store.ts

@@ -0,0 +1,38 @@
+import { Inject, Injectable } from '@angular/core';
+import { Observable, BehaviorSubject } from 'rxjs';
+import {
+  Action,
+  ActionsSubject,
+  INITIAL_STATE,
+  ReducerManager,
+  Store,
+} from '@ngrx/store';
+import { MockState } from './mock_state';
+
+@Injectable()
+export class MockStore<T> extends Store<T> {
+  public scannedActions$: Observable<Action>;
+
+  constructor(
+    private state$: MockState<T>,
+    actionsObserver: ActionsSubject,
+    reducerManager: ReducerManager,
+    @Inject(INITIAL_STATE) private initialState: T
+  ) {
+    super(state$, actionsObserver, reducerManager);
+    this.state$.next(this.initialState);
+    this.scannedActions$ = actionsObserver.asObservable();
+  }
+
+  setState(nextState: T): void {
+    this.state$.next(nextState);
+  }
+
+  addReducer() {
+    /* noop */
+  }
+
+  removeReducer() {
+    /* noop */
+  }
+}