Description

When Robolectric test is run on another thread (for example due to JUnit's timeout feature), Looper.getMainLooper() will stay on current thread. This causes issues with libraries that check and throw exception if any code is run on non-main thread (for example LiveData.setValue() from android architecture components breaks).

Steps to Reproduce

1. Create new blank android project
2. Add robolectric dependency
3. Run following test:

@RunWith(RobolectricTestRunner::class)
class LooperTest {
    @Test(timeout = 100L)
    fun mainLooperMatchesTimeout() {
        assertSame(Thread.currentThread(), Looper.getMainLooper().thread)
    }
}

If you remove timeout parameter from above test, it passes.

Robolectric & Android Version

Robolectric 3.8