Ensure that component prop 'context' really contains a React context … (

#1134)

* Ensure that component prop 'context' really contains a React context before using it

after switching to react-redux 6.0.0, we've had a lot of errors stating

Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

all over in our app. After digging deeper, we've discovered that we use a lot of (connected) components using a property named 'context' which conflicts with your new connectAdvanced code. So maybe you can improve the check on this.props.context a little bit to ensure it is used only if it really contains a valid React context.

* Update connectAdvanced.js

* Update connectAdvanced.js

* improved check whether context given as a prop is a real ReactContext

* added test for ignoring non-react-context values passed as a prop to the component

* Use react-is checks

* Just check Consumer. Good enough!

* improved check for context.Consumer

* added missing export 'isContextConsumer' in rollup config

rollup.config.js

@@ -2,7 +2,7 @@ import nodeResolve from 'rollup-plugin-node-resolve'
 import babel from 'rollup-plugin-babel'
 import replace from 'rollup-plugin-replace'
 import commonjs from 'rollup-plugin-commonjs'
-import {uglify} from 'rollup-plugin-uglify'
+import { uglify } from 'rollup-plugin-uglify'
 import pkg from './package.json'
 
 const env = process.env.NODE_ENV
@@ -22,14 +22,17 @@ const config = {
     nodeResolve(),
     babel({
       exclude: '**/node_modules/**',
-      runtimeHelpers: true,
+      runtimeHelpers: true
     }),
     replace({
       'process.env.NODE_ENV': JSON.stringify(env)
     }),
     commonjs({
       namedExports: {
-        'node_modules/react-is/index.js': ['isValidElementType'],
+        'node_modules/react-is/index.js': [
+          'isValidElementType',
+          'isContextConsumer'
+        ]
       }
     })
   ]

src/components/connectAdvanced.js

@@ -1,7 +1,7 @@
 import hoistStatics from 'hoist-non-react-statics'
 import invariant from 'invariant'
 import React, { Component, PureComponent } from 'react'
-import { isValidElementType } from 'react-is'
+import { isValidElementType, isContextConsumer } from 'react-is'
 
 import { ReactReduxContext } from './Context'
 
@@ -213,7 +213,12 @@ export default function connectAdvanced(
       }
 
       render() {
-        const ContextToUse = this.props.context || Context
+        const ContextToUse =
+          this.props.context &&
+          this.props.context.Consumer &&
+          isContextConsumer(<this.props.context.Consumer />)
+            ? this.props.context
+            : Context
 
         return (
           <ContextToUse.Consumer>

test/components/connect.spec.js

@@ -1564,6 +1564,36 @@ describe('React', () => {
       expect(actualState).toEqual(expectedState)
     })
 
+    it('should ignore non-react-context values that are passed as a prop to the component', () => {
+      class Container extends Component {
+        render() {
+          return <Passthrough />
+        }
+      }
+
+      const nonContext = { someProperty: {} }
+
+      let actualState
+
+      const expectedState = { foos: {} }
+
+      const decorator = connect(state => {
+        actualState = state
+        return {}
+      })
+      const Decorated = decorator(Container)
+
+      const store = createStore(() => expectedState)
+
+      rtl.render(
+        <ProviderMock store={store}>
+          <Decorated context={nonContext} />
+        </ProviderMock>
+      )
+
+      expect(actualState).toEqual(expectedState)
+    })
+
     it('should throw an error if the store is not in the props or context', () => {
       const spy = jest.spyOn(console, 'error').mockImplementation(() => {})