Testing

Question 1

What are the source sets of your project?

Answer 1

main
- the app’s code and resources

test

• for the app’s local unit tests
• run locally on machine’s JVM (high speed, low fidelity)

androidTest

• for the Android instrumented tests
• run on a real / emulated device (low speed, high fidelity)

Question 2

List the basic set up steps required for JUnit tests

Answer 2

@RunWith(JUnit4.class)
@SmallTest
public class MyTest {

private ClassUnderTest myClass;

    @Before
    public void setUp( ) {
        myClass = new MyClassUnderTest();
    }

Question 3

What are some basic assertions?

Answer 3

assertEquals( )
assertNull( )

assertThat(val1, is(equalTo(“required val”))

equalTo( ) is a matcher

Question 4

Which matcher can be used to mitigate for the unpredictable nature of float values?

Answer 4

Replace equalTo( ) matcher with closeTo(expectedValue, errorMargin)

Question 5

What is the code to implement hamcrest?

Answer 5

testImplementation “org.hamcrest:hamcrest-all:$hamcrestVersion”

implementation - available to all source sets

testImplementation & androidTestImplementation - only available in corresponding source sets

Question 6

How to get a mock context using AndroidX with JUnit4?

Answer 6

1 implement these:

testImplementation “androidx.test.ext:junit-ktx:$androidXTestExtKotlinRunnerVersion”

testImplementation “androidx.test:core-ktx:$androidXTestCoreVersion”

testImplementation "org.robolectric:robolectric:$robolectricVersion"
// Robolectric provides the simulated Android environment

2. Add @RunWith(AndroidJUnit4::class) above your test class.
// replaces default test runner; enables AndroidX Test to work with both unit and instrumented tests

3. ApplicationProvider.getApplicationContext( )

// this is simulated in unit tests, but it gets the real context for instrumented tests - same library (AndroidX Test) works for both

Question 7

How to fix the following warnigs?

1. No such manifest file: ./AndroidManifest.xml
2. “WARN: Android SDK 29 requires Java 9…”

Answer 7

1. 
testOptions.unitTests {
        includeAndroidResources = true
... 
    }
// the manifest is one of these resources

2. Configure AS to use Java 9 (too complicated for the Codelab)

Question 8

1. What does InstantExecutorRule do?
2. What is its dependency?
3. Syntax in the Test file?

Answer 8

1. A JUnit Rule that
   a) runs some before and after code
   b) runs all Architecture Component-related jobs synchronously on the same thread.
2. testImplementation “androidx.arch.core:core-testing:$archTestingVersion”
3. class MyViewModelTest {
   @get:Rule
   var instantExecutorRule = InstantTaskExecutorRule( )

Question 9

1. What makes LiveData difficult to implement in unit test files?
2. How to solve this?

Answer 9

1. A LiveData needs an Observer
   An Observer needs a LifecycleOwner (usually a Fragment or an Activity)
   No Fragment / Activity is available to a unit test.

2. 
val observer = Observer^LiveData^Type^^ { }
// empty lambda - doesn't need to do anything

myLiveData.observeForever(observer)
// must remember to 
finally{
.removeObserver(observer)
}

// get the value
val value = myLiveData.value

Alternatively, use some boilerplate from the Codelab in a util function that adds an observer, gets the value and removes the observer.

Question 10

Which 3 options is it a good idea to disable when running Espresso tests?

Answer 10

Window animation scale
Transition animation scale
Animator duration scale

Question 11

What lines need to be present in build.gradle(Module) to run Espresso?

What are they for?

Answer 11

testImplementation ‘junit:junit:4.12’

androidTestImplementation ‘com.android.support.test:runner:1.0.1’

androidTestImplementation ‘com.android.support.test.espresso:espresso-core:3.0.1’

// to execute tests, Espresso and UI Automator use JUnit as their testing framework

// at the end of defaultConfig{ }
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
// enables hooks controlling an Android component independently of the component's normal lifecycle

Question 12

1. Give syntax for using the 3 different types of Hamcrest expressions for Espresso
2. Which rule needs to be implemented at the top of TestClass in order to use them?

Answer 12

1.
// ViewMatcher (finds the view)
onView(withId(R.id.my_view))
// ViewAction (performs an action on the View)
.perform(click( ))
// ViewAssertion (checks the state of a View)
.check(matches(isDisplayed( )));

2.
@Rule
val mActivityRule = ActivityTestRule^^(MainActivity.class);

Question 13

When using Espresso, how do you assert the state of a Child View?

Answer 13

Iterate through the child views using an array (add a String array to strings.xml to facilitate finding each id)