Formatting, add test case for mergeProps equality optimization

Author: tgriesser

src/components/connect.js

@@ -82,6 +82,7 @@ export default function connect(mapStateToProps, mapDispatchToProps, mergeProps,
         if (!this.finalMapStateToProps) {
           return this.configureFinalMapState(store, props)
         }
+
         const state = store.getState()
         const stateProps = this.doStatePropsDependOnOwnProps ?
           this.finalMapStateToProps(state, props) :
@@ -93,28 +94,38 @@ export default function connect(mapStateToProps, mapDispatchToProps, mergeProps,
       configureFinalMapState(store, props) {
         const mappedState = mapState(store.getState(), props)
         const isFactory = typeof mappedState === 'function'
+
         this.finalMapStateToProps = isFactory ? mappedState : mapState
         this.doStatePropsDependOnOwnProps = this.finalMapStateToProps.length !== 1
-        return isFactory ? this.computeStateProps(store, props) : checkStateShape(mappedState)
+
+        return isFactory ?
+          this.computeStateProps(store, props) :
+          checkStateShape(mappedState)
       }
 
       computeDispatchProps(store, props) {
         if (!this.finalMapDispatchToProps) {
           return this.configureFinalMapDispatch(store, props)
         }
+
         const { dispatch } = store
         const dispatchProps = this.doDispatchPropsDependOnOwnProps ?
           this.finalMapDispatchToProps(dispatch, props) :
           this.finalMapDispatchToProps(dispatch)
+
         return checkStateShape(dispatchProps, true)
       }
 
       configureFinalMapDispatch(store, props) {
         const mappedDispatch = mapDispatch(store.dispatch, props)
         const isFactory = typeof mappedDispatch === 'function'
+
         this.finalMapDispatchToProps = isFactory ? mappedDispatch : mapDispatch
         this.doDispatchPropsDependOnOwnProps = this.finalMapDispatchToProps.length !== 1
-        return isFactory ? this.computeDispatchProps(store, props) : checkStateShape(mappedDispatch, true)
+
+        return isFactory ?
+          this.computeDispatchProps(store, props) :
+          checkStateShape(mappedDispatch, true)
       }
 
       updateStatePropsIfNeeded() {

test/components/connect.spec.js

@@ -39,7 +39,7 @@ describe('React', () => {
       @connect()
       class Container extends Component {
         render() {
-          return <div {...this.props} />
+          return <Passthrough {...this.props} />
         }
       }
 
@@ -1534,7 +1534,7 @@ describe('React', () => {
           updatedCount++
         }
         render() {
-          return <div {...this.props} />
+          return <Passthrough {...this.props} />
         }
       }
 
@@ -1612,5 +1612,32 @@ describe('React', () => {
       expect(memoizedReturnCount).toBe(2)
     })
 
+    it('should not call update if mergeProps return value has not changed', () => {
+      let mapStateCalls = 0
+      let renderCalls = 0
+      const store = createStore(stringBuilder)
+
+      @connect(() => ({ a: ++mapStateCalls }), null, () => ({ changed: false }))
+      class Container extends Component {
+        render() {
+          renderCalls++
+          return <Passthrough {...this.props} />
+        }
+      }
+
+      TestUtils.renderIntoDocument(
+        <ProviderMock store={store}>
+          <Container />
+        </ProviderMock>
+      )
+
+      expect(renderCalls).toBe(1)
+      expect(mapStateCalls).toBe(1)
+
+      store.dispatch({ type: 'APPEND', body: 'a' })
+
+      expect(mapStateCalls).toBe(2)
+      expect(renderCalls).toBe(1)
+    })
   })
 })