Move warnings from render => cWM

Author: mjackson

packages/react-router-dom/modules/BrowserRouter.js

@@ -18,13 +18,15 @@ class BrowserRouter extends React.Component {
 
   history = createHistory(this.props)
 
-  render() {
+  componentWillMount() {
     warning(
       !this.props.history,
       '<BrowserRouter> ignores the history prop. To use a custom history, ' +
-      'make sure you are using `import { Router }` and not `import { BrowserRouter as Router }`.'
+      'use `import { Router }` instead of `import { BrowserRouter as Router }`.'
     )
+  }
 
+  render() {
     return <Router history={this.history} children={this.props.children}/>
   }
 }

packages/react-router-dom/modules/HashRouter.js

@@ -17,13 +17,15 @@ class HashRouter extends React.Component {
 
   history = createHistory(this.props)
 
-  render() {
+  componentWillMount() {
     warning(
       !this.props.history,
       '<HashRouter> ignores the history prop. To use a custom history, ' +
-      'make sure you are using `import { Router }` and not `import { HashRouter as Router }`.'
+      'use `import { Router }` instead of `import { HashRouter as Router }`.'
     )
+  }
 
+  render() {
     return <Router history={this.history} children={this.props.children}/>
   }
 }

packages/react-router/modules/MemoryRouter.js

@@ -18,13 +18,15 @@ class MemoryRouter extends React.Component {
 
   history = createHistory(this.props)
 
-  render() {
+  componentWillMount() {
     warning(
       !this.props.history,
       '<MemoryRouter> ignores the history prop. To use a custom history, ' +
-      'make sure you are using `import { Router }` and not `import { MemoryRouter as Router }`.'
+      'use `import { Router }` instead of `import { MemoryRouter as Router }`.'
     )
+  }
 
+  render() {
     return <Router history={this.history} children={this.props.children}/>
   }
 }

packages/react-router/modules/StaticRouter.js

@@ -112,6 +112,14 @@ class StaticRouter extends React.Component {
   handleBlock = () =>
     noop
 
+  componentWillMount() {
+    warning(
+      !this.props.history,
+      '<StaticRouter> ignores the history prop. To use a custom history, ' +
+      'use `import { Router }` instead of `import { StaticRouter as Router }`.'
+    )
+  }
+
   render() {
     const { basename, context, location, ...props } = this.props
 
@@ -128,12 +136,6 @@ class StaticRouter extends React.Component {
       block: this.handleBlock
     }
 
-    warning(
-      !this.props.history,
-      '<StaticRouter> ignores the history prop. To use a custom history, ' +
-      'make sure you are using `import { Router }` and not `import { StaticRouter as Router }`.'
-    )
-
     return <Router {...props} history={history}/>
   }
 }