Merge pull request #515 from plotly/mkcor-testrun-instructions

Update instructions for running tests locally

Author: mkcor

CONTRIBUTING.md

@@ -27,12 +27,13 @@ Use the [GitHub flow][] when proposing contributions to this repository (i.e. cr
 
 ## Running the Tests
 
-**Warning:** _Tests do not currently run on windows. Track our progress: [#409](https://github.com/plotly/dash/issues/409)._
+**Warning:** _Tests do not currently run on Windows. Track our progress: [#409](https://github.com/plotly/dash/issues/409)._
 
 To run the tests, you can use Python's `unittest` module, or a test runner like `nose2`.
+For example, `python -m unittest tests.test_integration` will run the integration tests.
 
 To run all of the tests:
-`python -m unittest tests`
+`python -m unittest discover tests`
 
 Or:
 `nose2 -v`