Merge pull request reduxjs#720 from ellbee/always-call-verifyStateShape

Always call verifyStateShape for combined reducers

Author: gaearon

src/utils/combineReducers.js

@@ -15,8 +15,11 @@ function getErrorMessage(key, action) {
   );
 }
 
-function verifyStateShape(initialState, currentState) {
-  var reducerKeys = Object.keys(currentState);
+function verifyStateShape(inputState, outputState, action) {
+  var reducerKeys = Object.keys(outputState);
+  var argumentName = action && action.type === ActionTypes.INIT ?
+    'initialState argument passed to createStore' :
+    'previous state received by the reducer';
 
   if (reducerKeys.length === 0) {
     console.error(
@@ -26,25 +29,26 @@ function verifyStateShape(initialState, currentState) {
     return;
   }
 
-  if (!isPlainObject(initialState)) {
+  if (!isPlainObject(inputState)) {
     console.error(
-      'initialState has unexpected type of "' +
-      ({}).toString.call(initialState).match(/\s([a-z|A-Z]+)/)[1] +
-      '". Expected initialState to be an object with the following ' +
+      `The ${argumentName} has unexpected type of "` +
+      ({}).toString.call(inputState).match(/\s([a-z|A-Z]+)/)[1] +
+      `". Expected argument to be an object with the following ` +
       `keys: "${reducerKeys.join('", "')}"`
     );
     return;
   }
 
-  var unexpectedKeys = Object.keys(initialState).filter(
+  var unexpectedKeys = Object.keys(inputState).filter(
     key => reducerKeys.indexOf(key) < 0
   );
 
   if (unexpectedKeys.length > 0) {
     console.error(
       `Unexpected ${unexpectedKeys.length > 1 ? 'keys' : 'key'} ` +
-      `"${unexpectedKeys.join('", "')}" in initialState will be ignored. ` +
-      `Expected to find one of the known reducer keys instead: "${reducerKeys.join('", "')}"`
+      `"${unexpectedKeys.join('", "')}" found in ${argumentName}. ` +
+      `Expected to find one of the known reducer keys instead: ` +
+      `"${reducerKeys.join('", "')}". Unexpected keys will be ignored.`
     );
   }
 }
@@ -94,7 +98,6 @@ export default function combineReducers(reducers) {
   });
 
   var defaultState = mapValues(finalReducers, () => undefined);
-  var stateShapeVerified;
 
   return function combination(state = defaultState, action) {
     var finalState = mapValues(finalReducers, (reducer, key) => {
@@ -106,10 +109,7 @@ export default function combineReducers(reducers) {
     });
 
     if (process.env.NODE_ENV !== 'production') {
-      if (!stateShapeVerified) {
-        verifyStateShape(state, finalState);
-        stateShapeVerified = true;
-      }
+      verifyStateShape(state, finalState, action);
     }
 
     return finalState;

test/utils/combineReducers.spec.js

@@ -1,6 +1,6 @@
 import expect from 'expect';
 import { combineReducers } from '../../src';
-import { ActionTypes } from '../../src/createStore';
+import createStore, { ActionTypes } from '../../src/createStore';
 
 describe('Utils', () => {
   describe('combineReducers', () => {
@@ -130,61 +130,55 @@ describe('Utils', () => {
       spy.restore();
     });
 
-    it('should warn if initial state object does not match state object returned by reducer', () => {
+    it('should warn if input state object does not match state object returned by reducer', () => {
       const spy = expect.spyOn(console, 'error');
-      const reducerCreator = () => {
-        return combineReducers({
-          foo(state = {bar: 1}) {
-            return state;
-          },
-          baz(state = {qux: 3}) {
-            return state;
-          }
-        });
-      };
+      const reducer = combineReducers({
+        foo(state = {bar: 1}) {
+          return state;
+        },
+        baz(state = {qux: 3}) {
+          return state;
+        }
+      });
 
-      reducerCreator()({foo: {bar: 2}});
+      reducer({foo: {bar: 2}});
       expect(spy.calls.length).toBe(0);
 
-      reducerCreator()({
+      reducer({
         foo: {bar: 2},
         baz: {qux: 4}
       });
       expect(spy.calls.length).toBe(0);
 
-      reducerCreator()({bar: 2});
+      createStore(reducer, {bar: 2});
       expect(spy.calls[0].arguments[0]).toMatch(
-        /Unexpected key "bar".*instead: "foo", "baz"/
+        /Unexpected key "bar".*createStore.*instead: "foo", "baz"/
       );
 
-      reducerCreator()({bar: 2, qux: 4});
+      createStore(reducer, {bar: 2, qux: 4});
       expect(spy.calls[1].arguments[0]).toMatch(
-        /Unexpected keys "bar", "qux".*instead: "foo", "baz"/
+        /Unexpected keys "bar", "qux".*createStore.*instead: "foo", "baz"/
       );
 
-      reducerCreator()(1);
+      createStore(reducer, 1);
       expect(spy.calls[2].arguments[0]).toMatch(
-        /unexpected type of "Number".*keys: "foo", "baz"/
+        /createStore has unexpected type of "Number".*keys: "foo", "baz"/
       );
 
-      spy.restore();
-    });
-
-    it('should only check state shape on init', () => {
-      const spy = expect.spyOn(console, 'error');
-      const reducer = combineReducers({
-        foo(state = {bar: 1}) {
-          return state;
-        }
-      });
+      reducer({bar: 2});
+      expect(spy.calls[3].arguments[0]).toMatch(
+        /Unexpected key "bar".*reducer.*instead: "foo", "baz"/
+      );
 
-      reducer({bar: 1});
-      expect(spy.calls[0].arguments[0]).toMatch(
-        /Unexpected key "bar".*instead: "foo"/
+      reducer({bar: 2, qux: 4});
+      expect(spy.calls[4].arguments[0]).toMatch(
+        /Unexpected keys "bar", "qux".*reducer.*instead: "foo", "baz"/
       );
 
-      reducer({bar: 1});
-      expect(spy.calls.length).toBe(1);
+      reducer(1);
+      expect(spy.calls[5].arguments[0]).toMatch(
+        /reducer has unexpected type of "Number".*keys: "foo", "baz"/
+      );
 
       spy.restore();
     });