Issue #15: added test to make sure combined reducers handle incoming …

…actions only once

Change-Id: I9d4dc8d803372249df46b21b7feb57a89d783acf

packages/bricks/src/utils/combineNestedReducers.test.js

@@ -1,10 +1,10 @@
 import { combineNestedReducers, createFakeActionAndReducer } from '.';
 import { createStore } from 'redux';
 
-const [foo, fooAction] = createFakeActionAndReducer('FOO');
-const [bar, barAction] = createFakeActionAndReducer('BAR');
-const [baz, bazAction] = createFakeActionAndReducer('BAZ');
-const [bazong, bazongAction] = createFakeActionAndReducer('BAZONG');
+const [foo, fooAction, fooSpy] = createFakeActionAndReducer('FOO');
+const [bar, barAction, barSpy] = createFakeActionAndReducer('BAR');
+const [baz, bazAction, bazSpy] = createFakeActionAndReducer('BAZ');
+const [bazong, bazongAction, bazongSpy] = createFakeActionAndReducer('BAZONG');
 
 describe('When I combine some nested reducers', () => {
     let reducer;
@@ -26,6 +26,15 @@ describe('When I combine some nested reducers', () => {
                 store.dispatch(bazongAction);
             });
             describe('the resulting state', () => it('is correct', () => expect(store.getState()).toMatchSnapshot()));
+            describe('the “foo” reducer', () =>
+                it('handles the “foo” action only once', () => expect(fooSpy).toHaveBeenCalledTimes(1)));
+            describe('the “bar” reducer', () =>
+                it('handles the “bar” action only once', () => expect(barSpy).toHaveBeenCalledTimes(1)));
+            describe('the “baz” reducer', () =>
+                it('handles the “baz” action only once', () => expect(bazSpy).toHaveBeenCalledTimes(1)));
+            describe('the “bazong” reducer', () =>
+                it('handles the “bazong” action only once', () => expect(bazongSpy).toHaveBeenCalledTimes(1)));
         });
+        afterEach(() => jest.clearAllMocks());
     });
 });

packages/bricks/src/utils/createFakeActionAndReducer.js

@@ -1,5 +1,14 @@
 /* this is used only in unit tests */
-export default type => [
-    (state = {}, action = {}) => (action.type === type ? { ...state, value: action.value } : state),
-    { type, value: type.toLowerCase() }
-];
+/* global jest */
+export default type => {
+    const spy = jest.fn();
+    const reducer = (state = {}, action = {}) => {
+        if (action.type === type) {
+            spy(action.value);
+            return { ...state, value: action.value };
+        }
+        return state;
+    };
+    const action = { type, value: type.toLowerCase() };
+    return [reducer, action, spy];
+};