How to build an Isolated Drupal instance for testing
You could just use different git branches to isolate your code tests.

git checkout -b iss_tst1
&lt;make changes&gt;
git add &lt;changes&gt;
git commit -m "my new changes" &lt;changes&gt;

git checkout -b iss_tst2
&lt;make changes&gt;
git add &lt;changes&gt;
git commit -m "other new independent changes" &lt;changes&gt;


Then you should be able to run independent tests on each branch.