Exception in thread "main" java.lang.NoClassDefFoundError: junit/textui/ResultPrinter
Finally found it. It's in the Run/Debug Configurations dialog. Disabled JUnit and it compiles again.
Usually this problem is caused because of wrong test type: Junit instead of Android Test
For standard JUnit tests, you are missing the JUnit library, try adding this in build.gradle:
dependencies { ... testCompile 'junit:junit:4.12' ...}And make sure you are putting the tests in the "test" directory parallell to the "main" package (instrumentation tests goes into "androidTest", but that is different setup).