Since version 1.1 of the android gradle plugin it supports standard JUnit unit tests run outside of the device in the src/test folder instead of src/androidTest.
However these aren't shown in the Projects tab, only in the Files tab. Also the classpath for these tests isn't correct as testCompile dependencies in the build.gradle are ignored and references to those classes have red underlining in the editor.
Having this support would be a useful feature since this would mean that tests using RobolectricGradleTestRunner will then be much easier to create. Such tests are significantly easier and quicker to run than standard instrumentation tests.