manhduy

Code is clean if it can be understood easily – by everyone on the team. Clean code can be read and enhanced by a developer other than its original author. With understandability comes readability, changeability, extensibility and maintainability.

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General rules

1. Follow standard conventions.
2. Keep it simple stupid. Simpler is always better. Reduce complexity as much as possible.
3. Boy scout rule. Leave the campground cleaner than you found it.
4. Always find root cause. Always look for the root cause of a problem.

Design rules

manhduy

@HiltAndroidApp
class App : Application() {
}

manhduy

@Test
fun test_DisplaySum_WhenSumLiveDataChange() {
    //Given
    val scenario = launchActivity<CalculatorActivity>()
    //When
    sum.postValue(10)
    //Then
    onView(withId(R.id.tvSum)).check(matches(withText("10")))
}

manhduy

@HiltAndroidTest
@RunWith(AndroidJUnit4::class)
class CalculatorActivityTest {

    @BindValue
    @JvmField
    val viewModel = mockk<CalculatorViewModel>(relaxed = true)

    @get:Rule
    var hiltRule = HiltAndroidRule(this)

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android {
    defaultConfig {
        ...
        testInstrumentationRunner "com.duyha.hilttestingsample.TestRunner"
    }
}

manhduy

class TestRunner : AndroidJUnitRunner() {

    override fun newApplication(cl: ClassLoader?, name: String?, context: Context?): Application {
        return super.newApplication(cl, HiltTestApplication::class.java.name, context)
    }
}

manhduy

@Before
fun setUp() {
    calculatorService = mockk<CalculatorService>()
    viewModel = CalculatorViewModel(calculatorService)
}

@Test
fun test_SumReturnFromCalculator_LiveDataChanged() {
    //Given
    every { calculatorService.sum(a, b) } returns sum

manhduy

@Module
@InstallIn(SingletonComponent::class)
class AppModule {

    @Singleton
    @Provides
    fun provideCalculator(): Calculator = Calculator()
}

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@AndroidEntryPoint
class CalculatorActivity : AppCompatActivity() {

    private val viewModel: CalculatorViewModel by viewModels()
    
    ...
}

manhduy

@HiltViewModel
class CalculatorViewModel @Inject constructor(
    private val calculator: Calculator
) : ViewModel() {

    ...
}