Issue #7424: test/README update with jest snapshot flow

test/README.md

@@ -46,11 +46,23 @@ In addition to an `index.js`, these configCases require a `webpack.config.js` is
 #### statsCases (`StatsTestCases.test.js`)
 Stats cases are similar to configCases except specifically focusing on the `expected` output of your stats. Instead of writing to the console, however the output of stats will be written to disk.
 
-By default, the "expected" outcome is a pain to write by hand so instead when statsCases are run the following happens:
+By default, the "expected" outcome is a pain to write by hand so instead when statsCases are run, runner is checking output using jest's awesome snapshot functionality.
 
-* Checks for `expected.txt` file containing expected results.
-* If the `expected.txt` doesn't match what is output, then an `actual.txt` stats output file will be created and the test will fail. (A typical workflow for stats cases is to fail the test and copy the results from `actual.txt` to `expected.txt`.)
-* If the actual output matches `expected.txt`, the tests passes and you are free to submit that PR with pride!!!
+Basically you don't need to write any expected behaviors your self. The assumption is that the stats output from your test code is what you expect.
+
+Please follow the approach described bellow:
+
+* write your test code in ```statsCases/``` folder by creating a separate folder for it, for example
+```statsCases/some-file-import-stats/index.js```
+```
+    import(./someModule);
+```
+** dont's forget the ```webpack.config.js```
+* run the test
+* jest will automatically add the output from your test code to ```StatsTestCases.test.js.snap``` and you can always check your results there
+* Next time test will run -> runner will compare results against your output written to snapshot previously
+
+You can read more about SnapShot testing [right here](https://facebook.github.io/jest/docs/en/snapshot-testing.html)
 
 ## Questions? Comments?
 If you are still nervous or don't quite understand, please submit an issue and tag us in it, and provide a relevant PR while working on!