add tests for persistState.js

Author: ellbee

src/persistState.js

@@ -65,7 +65,7 @@ export default function persistState(sessionId, stateDeserializer = null, action
         try {
           localStorage.setItem(key, JSON.stringify(store.getState()));
         } catch (e) {
-          console.warn('Could not write debug session from localStorage:', e);
+          console.warn('Could not write debug session to localStorage:', e);
         }
 
         return action;

test/persistState.spec.js

@@ -0,0 +1,123 @@
+import expect from 'expect';
+import devTools from '../src/devTools';
+import persistState from '../src/persistState';
+import { compose, createStore } from 'redux';
+
+describe('persistState', () => {
+  let savedLocalStorage = global.localStorage;
+
+  beforeEach(() => {
+    global.localStorage = {
+      store: {},
+      getItem(key) {
+        return this.store[key] || null;
+      },
+      setItem(key, value) {
+        this.store[key] = value;
+      },
+      removeItem(key) {
+        delete this.store[key];
+      },
+      clear() {
+        this.store = {};
+      }
+    };
+  });
+
+  after(() => {
+    global.localStorage = savedLocalStorage;
+  });
+
+  const reducer = (state = 0, action) => {
+    switch (action.type) {
+    case 'INCREMENT':
+      return state + 1;
+    case 'DECREMENT':
+      return state - 1;
+    default:
+      return state;
+    }
+  };
+
+  it('should persist state', () => {
+    const finalCreateStore = compose(devTools(), persistState('id'))(createStore);
+    const store = finalCreateStore(reducer);
+    expect(store.getState()).toBe(0);
+
+    store.dispatch({ type: 'INCREMENT' });
+    store.dispatch({ type: 'INCREMENT' });
+    expect(store.getState()).toBe(2);
+
+    const store2 = finalCreateStore(reducer);
+    expect(store2.getState()).toBe(2);
+  });
+
+  it('should not persist state if no session id', () => {
+    const finalCreateStore = compose(devTools(), persistState())(createStore);
+    const store = finalCreateStore(reducer);
+    expect(store.getState()).toBe(0);
+
+    store.dispatch({ type: 'INCREMENT' });
+    store.dispatch({ type: 'INCREMENT' });
+    expect(store.getState()).toBe(2);
+
+    const store2 = finalCreateStore(reducer);
+    expect(store2.getState()).toBe(0);
+  });
+
+  it('should run with a custom state deserializer', () => {
+    const oneLess = state => state === undefined ? -1 : state - 1;
+    const finalCreateStore = compose(devTools(), persistState('id', oneLess))(createStore);
+    const store = finalCreateStore(reducer);
+    expect(store.getState()).toBe(0);
+
+    store.dispatch({ type: 'INCREMENT' });
+    store.dispatch({ type: 'INCREMENT' });
+    expect(store.getState()).toBe(2);
+
+    const store2 = finalCreateStore(reducer);
+    expect(store2.getState()).toBe(1);
+  });
+
+  it('should run with a custom action deserializer', () => {
+    const incToDec = action => action.type === 'INCREMENT' ? { type: 'DECREMENT' } : action;
+    const finalCreateStore = compose(devTools(), persistState('id', null, incToDec))(createStore);
+    const store = finalCreateStore(reducer);
+    expect(store.getState()).toBe(0);
+
+    store.dispatch({ type: 'INCREMENT' });
+    store.dispatch({ type: 'INCREMENT' });
+    expect(store.getState()).toBe(2);
+
+    const store2 = finalCreateStore(reducer);
+    expect(store2.getState()).toBe(-2);
+  });
+
+  it('should warn if read from localStorage fails', () => {
+    const spy = expect.spyOn(console, 'warn');
+    const finalCreateStore = compose(devTools(), persistState('id'))(createStore);
+    delete global.localStorage.getItem;
+    finalCreateStore(reducer);
+
+    expect(spy.calls).toContain(
+      /Could not read debug session from localStorage/,
+      (call, errMsg) => call.arguments[0].match(errMsg)
+    );
+
+    spy.restore();
+  });
+  it('should warn if write to localStorage fails', () => {
+    const spy = expect.spyOn(console, 'warn');
+    const finalCreateStore = compose(devTools(), persistState('id'))(createStore);
+    delete global.localStorage.setItem;
+    const store = finalCreateStore(reducer);
+
+    store.dispatch({ type: 'INCREMENT' });
+    expect(spy.calls).toContain(
+      /Could not write debug session to localStorage/,
+      (call, errMsg) => call.arguments[0].match(errMsg)
+    );
+
+    spy.restore();
+  });
+});