TestCt.kt

@RunWith(AndroidJUnit4::class)
class SampleTest {

    private lateinit var personDao: PersonDao
    private lateinit var db: AppDatabase

    @Before
    fun createDb() {
        db = Room.inMemoryDatabaseBuilder(
                InstrumentationRegistry.getContext(), AppDatabase::class.java).build()
        personDao = db.personDao()
    }

    @After
    @Throws(IOException::class)
    fun closeDb() {
        db.close()
    }

    @Test
    @Throws(Exception::class)
    fun writePersonAndReadById() = runBlocking {
        val person = createTestPerson()
        val id = personDao.insert(person)
        val retrievedPerson = personDao.getPersonById(id)
        assertThat(person, equalTo(retrievedPerson))
    }
}