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Prevent ConnectedRouter from re-rendering on every redux store update #208

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merged 6 commits into from
Dec 27, 2018
Merged

Prevent ConnectedRouter from re-rendering on every redux store update #208

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82576ea
Replace Component by PureComponent to enable shallow compare
brendonpagano Dec 14, 2018
a97b204
Add test to count the times rendered when mounted
brendonpagano Dec 15, 2018
e1bcf99
Create a test for non-related actions being fired
brendonpagano Dec 15, 2018
5236391
Keep the same prop usage from other tests
brendonpagano Dec 15, 2018
1131d79
Remove MockProvider and use redux's Provider instead
brendonpagano Dec 27, 2018
7b22f4d
Remove location and action props from ConnectedRouter
brendonpagano Dec 27, 2018
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19 changes: 4 additions & 15 deletions src/ConnectedRouter.js
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Original file line number Diff line number Diff line change
@@ -1,21 +1,20 @@
import React, { Component } from 'react'
import React, { PureComponent } from 'react'
import PropTypes from 'prop-types'
import { connect, ReactReduxContext } from 'react-redux'
import { Router } from 'react-router'
import { onLocationChanged } from './actions'
import createSelectors from './selectors'

const createConnectedRouter = (structure) => {
const { getIn } = structure
const { getRouter, getLocation } = createSelectors(structure)
const { getLocation } = createSelectors(structure)
/*
* ConnectedRouter listens to a history object passed from props.
* When history is changed, it dispatches action to redux store.
* Then, store will pass props to component to render.
* This creates uni-directional flow from history->store->router->components.
*/

class ConnectedRouter extends Component {
class ConnectedRouter extends PureComponent {
constructor(props) {
super(props)

Expand Down Expand Up @@ -90,21 +89,11 @@ const createConnectedRouter = (structure) => {
location: PropTypes.object.isRequired,
push: PropTypes.func.isRequired,
}).isRequired,
location: PropTypes.oneOfType([
PropTypes.object,
PropTypes.string,
]).isRequired,
action: PropTypes.string.isRequired,
basename: PropTypes.string,
children: PropTypes.oneOfType([ PropTypes.func, PropTypes.node ]),
onLocationChanged: PropTypes.func.isRequired,
}

const mapStateToProps = state => ({
action: getIn(getRouter(state), ['action']),
location: getIn(getRouter(state), ['location']),
})

const mapDispatchToProps = dispatch => ({
onLocationChanged: (location, action) => dispatch(onLocationChanged(location, action))
})
Expand All @@ -127,7 +116,7 @@ const createConnectedRouter = (structure) => {
context: PropTypes.object,
}

return connect(mapStateToProps, mapDispatchToProps)(ConnectedRouterWithContext)
return connect(null, mapDispatchToProps)(ConnectedRouterWithContext)
}

export default createConnectedRouter
140 changes: 81 additions & 59 deletions test/ConnectedRouter.test.js
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Original file line number Diff line number Diff line change
@@ -1,20 +1,19 @@
import 'raf/polyfill'
import React, { Children, Component } from 'react'
import PropTypes from 'prop-types'
import React from 'react'
import configureStore from 'redux-mock-store'
import { createStore, combineReducers } from 'redux'
import { createStore, combineReducers, applyMiddleware, compose } from 'redux'
import { ActionCreators, instrument } from 'redux-devtools'
import Enzyme from 'enzyme'
import Adapter from 'enzyme-adapter-react-16'
import { createMemoryHistory } from 'history'
import { Route } from 'react-router'
import { ReactReduxContext } from 'react-redux'
import { Provider } from 'react-redux'
import createConnectedRouter from '../src/ConnectedRouter'
import { onLocationChanged } from '../src/actions'
import plainStructure from '../src/structure/plain'
import immutableStructure from '../src/structure/immutable'
import seamlessImmutableStructure from '../src/structure/seamless-immutable'
import { connectRouter, ConnectedRouter } from '../src'
import { connectRouter, ConnectedRouter, routerMiddleware } from '../src'

Enzyme.configure({ adapter: new Adapter() })

Expand Down Expand Up @@ -69,11 +68,11 @@ describe('ConnectedRouter', () => {

it('calls `props.onLocationChanged()` when location changes.', () => {
mount(
<MockProvider store={store}>
<Provider store={store}>
<ConnectedRouter {...props}>
<Route path="/" render={() => <div>Home</div>} />
</ConnectedRouter>
</MockProvider>
</Provider>
)

expect(onLocationChangedSpy.mock.calls).toHaveLength(1)
Expand All @@ -86,11 +85,11 @@ describe('ConnectedRouter', () => {

it('unlistens the history object when unmounted.', () => {
const wrapper = mount(
<MockProvider store={store}>
<Provider store={store}>
<ConnectedRouter {...props}>
<Route path="/" render={() => <div>Home</div>} />
</ConnectedRouter>
</MockProvider>
</Provider>
)

expect(onLocationChangedSpy.mock.calls).toHaveLength(1)
Expand All @@ -109,11 +108,11 @@ describe('ConnectedRouter', () => {
it('supports custom context', () => {
const context = React.createContext(null)
mount(
<MockProvider store={store} context={context}>
<Provider store={store} context={context}>
<ConnectedRouter {...props} context={context}>
<Route path="/" render={() => <div>Home</div>} />
</ConnectedRouter>
</MockProvider>
</Provider>
)

expect(onLocationChangedSpy.mock.calls).toHaveLength(1)
Expand All @@ -123,7 +122,63 @@ describe('ConnectedRouter', () => {

expect(onLocationChangedSpy.mock.calls).toHaveLength(3)
})
})

it('only renders one time when mounted', () => {
let renderCount = 0

const RenderCounter = () => {
renderCount++
return null
}

mount(
<Provider store={store}>
<ConnectedRouter {...props}>
<Route path="/" component={RenderCounter} />
</ConnectedRouter>
</Provider>
)

expect(renderCount).toBe(1)
})

it('does not render again when non-related action is fired', () => {
// Initialize the render counter variable
let renderCount = 0

// Create redux store with router state
store = createStore(
combineReducers({
incrementReducer: (state = 0, action = {}) => {
if (action.type === 'testAction')
return ++state

return state
},
router: connectRouter(history)
}),
compose(applyMiddleware(routerMiddleware(history)))
)


const RenderCounter = () => {
renderCount++
return null
}

mount(
<Provider store={store}>
<ConnectedRouter {...props}>
<Route path="/" component={RenderCounter} />
</ConnectedRouter>
</Provider>
)

store.dispatch({ type: 'testAction' })
history.push('/new-location')
expect(renderCount).toBe(2)
})
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@AnnaTsu Just so I understand what's going on here, store.dispatch() will not re-render RenderCounter, BUT history.push() will, correct? Therefore renderCount should be 2.

initial render + history.push() = 2 renders

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Exactly. Initial render times upon mount should be one.

Then, i fire an action that has no connection to what ConnectedRouter should listen to, and modify the history (something that the component should re-render).

So, the expected render times should be 2.

})

describe('with immutable structure', () => {
let ConnectedRouter
Expand All @@ -134,11 +189,11 @@ describe('ConnectedRouter', () => {

it('calls `props.onLocationChanged()` when location changes.', () => {
mount(
<MockProvider store={store}>
<Provider store={store}>
<ConnectedRouter {...props}>
<Route path="/" render={() => <div>Home</div>} />
</ConnectedRouter>
</MockProvider>
</Provider>
)

expect(onLocationChangedSpy.mock.calls).toHaveLength(1)
Expand All @@ -151,11 +206,11 @@ describe('ConnectedRouter', () => {

it('unlistens the history object when unmounted.', () => {
const wrapper = mount(
<MockProvider store={store}>
<Provider store={store}>
<ConnectedRouter {...props}>
<Route path="/" render={() => <div>Home</div>} />
</ConnectedRouter>
</MockProvider>
</Provider>
)

expect(onLocationChangedSpy.mock.calls).toHaveLength(1)
Expand All @@ -174,11 +229,11 @@ describe('ConnectedRouter', () => {
it('supports custom context', () => {
const context = React.createContext(null)
mount(
<MockProvider store={store} context={context}>
<Provider store={store} context={context}>
<ConnectedRouter {...props} context={context}>
<Route path="/" render={() => <div>Home</div>} />
</ConnectedRouter>
</MockProvider>
</Provider>
)

expect(onLocationChangedSpy.mock.calls).toHaveLength(1)
Expand All @@ -199,11 +254,11 @@ describe('ConnectedRouter', () => {

it('calls `props.onLocationChanged()` when location changes.', () => {
mount(
<MockProvider store={store}>
<Provider store={store}>
<ConnectedRouter {...props}>
<Route path="/" render={() => <div>Home</div>} />
</ConnectedRouter>
</MockProvider>
</Provider>
)

expect(onLocationChangedSpy.mock.calls).toHaveLength(1)
Expand All @@ -216,11 +271,11 @@ describe('ConnectedRouter', () => {

it('unlistens the history object when unmounted.', () => {
const wrapper = mount(
<MockProvider store={store}>
<Provider store={store}>
<ConnectedRouter {...props}>
<Route path="/" render={() => <div>Home</div>} />
</ConnectedRouter>
</MockProvider>
</Provider>
)

expect(onLocationChangedSpy.mock.calls).toHaveLength(1)
Expand Down Expand Up @@ -254,11 +309,11 @@ describe('ConnectedRouter', () => {

it('resets to the initial url', () => {
mount(
<MockProvider store={store}>
<Provider store={store}>
<ConnectedRouter {...props}>
<div>Test</div>
</ConnectedRouter>
</MockProvider>
</Provider>
)

let currentPath
Expand All @@ -276,11 +331,11 @@ describe('ConnectedRouter', () => {

it('handles toggle after history change', () => {
mount(
<MockProvider store={store}>
<Provider store={store}>
<ConnectedRouter {...props}>
<div>Test</div>
</ConnectedRouter>
</MockProvider>
</Provider>
)

let currentPath
Expand All @@ -300,36 +355,3 @@ describe('ConnectedRouter', () => {
})
})
})

// MockProvider mocks react-redux's Provider component
class MockProvider extends Component {
constructor(props) {
super(props)
const { store } = props
this.state = {
storeState: store.getState(),
store,
}
}
render() {
const Context = this.props.context || ReactReduxContext

return (
<Context.Provider value={this.state}>
{Children.only(this.props.children)}
</Context.Provider>
)
}
}

const storeShape = PropTypes.shape({
subscribe: PropTypes.func.isRequired,
dispatch: PropTypes.func.isRequired,
getState: PropTypes.func.isRequired,
})

MockProvider.propTypes = {
context: PropTypes.object,
store: storeShape.isRequired,
children: PropTypes.element.isRequired,
}