Simplifies reducer tests

src/components/__tests__/counter_spec.tsx

@@ -6,7 +6,7 @@ import * as ReactShallowRenderer from 'react-test-renderer/shallow'
 import { createStore } from 'redux'
 
 import { Counter } from '../counter'
-import { reducers } from '../../reducers'
+import reducers from '../../reducers'
 
 describe('components/Counter', () => {
 

src/index.tsx

@@ -4,12 +4,12 @@ import * as redux from 'redux'
 import { Provider } from 'react-redux'
 import thunk from 'redux-thunk'
 
-import * as state from './reducers'
+import reducers, * as state from './reducers'
 
 import { Counter } from './components/counter'
 
 const store: redux.Store<state.All> = redux.createStore(
-  state.reducers,
+  reducers,
   {} as state.All,
   redux.applyMiddleware(thunk),
 )

src/reducers/__tests__/__snapshots__/index_spec.ts.snap

@@ -0,0 +1,34 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`reducers/counter increments 1`] = `
+Object {
+  "counter": Object {
+    "value": 6,
+  },
+  "error": "",
+  "isLoading": false,
+  "isSaving": false,
+}
+`;
+
+exports[`reducers/counter restores state 1`] = `
+Object {
+  "counter": Object {
+    "value": 14,
+  },
+  "error": "",
+  "isLoading": false,
+  "isSaving": false,
+}
+`;
+
+exports[`reducers/counter starts at 0 1`] = `
+Object {
+  "counter": Object {
+    "value": 0,
+  },
+  "error": "",
+  "isLoading": false,
+  "isSaving": false,
+}
+`;

src/reducers/__tests__/index_spec.ts

@@ -1,37 +1,31 @@
-import { createStore } from 'redux'
+import reducers, {
+  initialState,
+} from '../index'
 
-import { reducers } from '../index'
 import {
-  incrementCounter,
+  incrementCounter
 } from '../../actions'
 
+const resultOf = actions =>
+  actions.reduce(reducers, initialState)
+
 describe('reducers/counter', () => {
-  it('starts at 0', () => {
-    const store = createStore(reducers)
-    const { counter } = store.getState()
-    expect(counter.value).toEqual(0)
-  })
+  it('starts at 0', () =>
+    expect(resultOf([])).toMatchSnapshot())
 
-  it('increments', (done) => {
-    const store = createStore(reducers)
-    store.subscribe(() => {
-      const { counter } = store.getState()
-      expect(counter.value).toEqual(3)
-      done()
-    })
-    store.dispatch(incrementCounter(3))
-  })
+  it('increments', () =>
+    expect(resultOf([
+      incrementCounter(1),
+      incrementCounter(2),
+      incrementCounter(3),
+    ])).toMatchSnapshot())
 
-  it('restores state', (done) => {
-    const store = createStore(reducers)
-    store.subscribe(() => {
-      const { counter } = store.getState()
-      expect(counter.value).toEqual(14)
-      done()
-    })
-    store.dispatch({
-      type: 'LOAD_COUNT_SUCCESS',
-      request: {},
-      response: { value: 14 } })
-  })
+  it('restores state', () =>
+    expect(resultOf([
+      {
+        type: 'LOAD_COUNT_SUCCESS',
+        request: {},
+        response: { value: 14 },
+      }
+    ])).toMatchSnapshot())
 })

src/reducers/index.ts

@@ -48,11 +48,11 @@ function error (state: string = '', action: Action): string {
   }
 }
 
-const initialState: Counter = {
+const counterState: Counter = {
   value: 0,
 }
 
-function counter (state: Counter = initialState, action: Action): Counter {
+function counter (state: Counter = counterState, action: Action): Counter {
   switch (action.type) {
     case 'INCREMENT_COUNTER':
       const { delta } = action
@@ -69,9 +69,18 @@ function counter (state: Counter = initialState, action: Action): Counter {
   }
 }
 
-export const reducers = combineReducers<All>({
+export const initialState = {
+  counter: counterState,
+  isSaving: false,
+  isLoading: false,
+  error: '',
+}
+
+const reducers = combineReducers<All>({
   counter,
   isSaving,
   isLoading,
   error,
 })
+
+export default reducers