This is a know issue, that happens sometimes.
When trying to run all tests at once, this message is displayed
No tests found. This usually means that your test classes are not in the form that your test runner expects (e.g. don't inherit from TestCase or lack @Test annotations).
But this does not happen when you run a single class, or a single test.
I'm closing this issue due to a lack of evidences.
Seems like in the update to 3.0.1 of Espresso and 1.0.1 of runner, the bug was fix.
If you are facing this issue feel free to reopen the issue.
This is a know issue, that happens sometimes. When trying to run all tests at once, this message is displayed
But this does not happen when you run a single class, or a single test.