room-database-testing-example.kt

@RunWith(AndroidJUnit4ClassRunner::class)
class UserDaoTest {
    private lateinit var db: TestUserDatabase
    private lateinit var userDao: UserDao

    @Before
    fun createDb() {
        val context = InstrumentationRegistry.getInstrumentation().targetContext
        db = Room.inMemoryDatabaseBuilder(context, TestUserDatabase::class.java).build()
        userDao = db.userDao()
    }

    @After
    fun closeDb() {
        db.close()
    }

    @Test
    @Throws(Exception::class)
    fun insertAndGetUser() {
        val user = User("John", "Doe")
        userDao.insert(user)
        val savedUser = userDao.getUserById(1)
        assertEquals(user.firstName, savedUser.firstName)
        assertEquals(user.lastName, savedUser.lastName)
    }

    @Test
    @Throws(Exception::class)
    fun deleteUser() {
        val user = User("John", "Doe")
        userDao.insert(user)
        userDao.delete(user)
        val savedUser = userDao.getUserById(1)
        assertNull(savedUser)
    }
}