Implement testing in React 0.14, 15, 16, add wallaby.js, use enzyme (r…

…eduxjs#984)

* begin work

* enable testing on 4 react versions on travis
* enable local testing on 4 versions
* enable running wallaby if installed

* Fix tests in 0.14, 15, and 16

* remove 15.4, not really necessary and it requires a tweak to the install script

* fix 2 major potential issues

1) by putting all the installs in setupTestEnv into a single npm command, npm --no-save becomes possible. When they are on separate lines, the 2nd npm i removes the previous line's work
2) after test runs, we restore the node_modules to what devDependencies says

* update contributing docs and add missing test:watch

* re-work to use subdirectories for testing specific react versions

caveat: collecting coverage does not work yet, we need to combine the lcov reports

* fully working! with merged coverage!

* fix linting, remove unnecessary file

* fix test:watch

* fix travis tests to run in parallel for each version

* oops, didn't make travis run the CI test

* sigh... npm syntax error

* speed up test suites by only installing the specific version needed

* remove unused plugin

* simplify test script options in package.json

use the REACT env variable to run tests for a specific version, set it to "all" to run for all supported versions

* simpler gitignore

* remove unnecessary coverage merging, codecov does that automagically

* simplify test running

* new docs on testing specific React versions

* move scripts to test/, remove unused dep

* revert unintentional cosmetic changes

* add default version for "npm test"

* revert unintentional cosmetic changes to test import order

* restore the correct test renderer version

* fix travis, add a note about the matrix needing update on adding a React version

* Add cross-spawn dependency

* Use cross-spawn for consistent NPM installations cross-platform

.babelrc

@@ -25,7 +25,6 @@
   "env": {
     "test": {
       "plugins": [
-        "istanbul",
         ["transform-es2015-modules-commonjs", { "loose": true }]
       ]
     },

.gitignore

@@ -6,3 +6,8 @@ lib
 .nyc_output
 coverage
 es
+test/**/lcov.info
+test/**/lcov-report
+test/react/*/test/**/*.spec.js
+test/react/**/src
+lcov.info

.travis.yml

@@ -1,8 +1,18 @@
 language: node_js
 node_js:
   - "8"
+before_install:
+  - 'nvm install-latest-npm'
+env:
+  matrix:
+  - REACT=0.14
+  - REACT=15
+  - REACT=16.2
+  - REACT=16.3
+  - REACT=16.4
+sudo: false
 script:
   - npm run lint
-  - npm test
+  - npm run test
 after_success:
   - npm run coverage

CONTRIBUTING.md

@@ -35,21 +35,135 @@ npm run build:umd:min
 
 ### Testing and Linting
 
-To run the tests:
+To run the tests in the latest React version:
 ```
 npm run test
 ```
 
+To run in explicit React versions (the number is the version, so `test:16.3` will run in React version `16.3`):
+```
+REACT=16.4 npm run test:ci
+```
+
+To run tests in all supported React versions, `0.14`, `15`, `16.2`, `16.3`, `16.4`,
+```
+REACT=all npm run test:ci
+``` 
+
 To continuously watch and run tests, run the following:
 ```
-npm run test:watch
+npm run test -- --watch
 ```
 
 To perform linting with `eslint`, run the following:
 ```
 npm run lint
 ```
 
+#### Adding a new React version for testing
+
+To add a new version of React to test react-redux against, create a directory structure
+in this format for React version `XX`:
+
+```
+test/
+ react/
+  XX/
+   package.json
+   test/
+    getTestDeps.js
+```
+
+So, for example, to test against React 15.4:
+
+
+```
+test/
+ react/
+  15.4/
+   package.json
+   test/
+    getTestDeps.js
+```
+
+The package.json must include the correct versions of `react`, `react-dom`,
+`react-test-renderer` and the correct enzyme adapter for the React version
+being used, as well as the needed `create-react-class`, `jest`, `enzyme` versions
+and the `jest` and `scripts` sections copied verbatim like this:
+
+```json
+{
+  "private": true,
+  "devDependencies": {
+    "create-react-class": "^15.6.3",
+    "enzyme": "^3.3.0",
+    "enzyme-adapter-react-15.4": "^1.0.6",
+    "jest": "^23.4.2",
+    "react": "15.4",
+    "react-dom": "15.4",
+    "react-test-renderer": "15.4"
+  },
+  "jest": {
+    "testURL": "http://localhost",
+    "collectCoverage": true,
+    "coverageDirectory": "./coverage"
+  },
+  "scripts": {
+    "test": "jest"
+  }
+}
+```
+
+`getTestDeps.js` should load the version-specific enzyme adapter and
+test renderer (all versions newer than 0.14 use `react-test-renderer`,
+0.14 uses `react-addons-test-utils`):
+
+```js
+import enzyme from 'enzyme'
+import TestRenderer from 'react-test-renderer'
+import Adapter from 'enzyme-adapter-react-15.4'
+
+enzyme.configure({ adapter: new Adapter() })
+
+export { TestRenderer, enzyme }
+```
+
+Then you can run tests against this version with:
+
+```
+REACT=15.4 npm run test
+```
+
+and the new version will also be automatically included in
+
+```
+REACT=all npm run test
+```
+
+In addition, the new version should be added to the .travis.yml matrix list:
+
+```yaml
+language: node_js
+node_js:
+  - "8"
+before_install:
+  - 'nvm install-latest-npm'
+env:
+  matrix:
+  - REACT=0.14
+  - REACT=15
+  - REACT=15.4
+  - REACT=16.2
+  - REACT=16.3
+  - REACT=16.4
+sudo: false
+script:
+  - npm run lint
+  - npm run test
+after_success:
+  - npm run coverage
+```
+
 ### New Features
 
 Please open an issue with a proposal for a new feature or refactoring before starting on the work. We don't want you to waste your efforts on a pull request that we won't want to accept.