13. Using Espresso to Test a Fragment

L5 P3 A09 Using Espresso To Test A Fragment

Time to write an Espresso test.

Step 1: Turn off Animations

For Espresso UI testing, it's best practice to turn animations off (also your test will run faster!):

  1. On your testing device, go to Settings > Developer options.
  2. Disable these three settings: Window animation scale, Transition animation scale and Animator duration scale:

Step 2: Add an Espresso Test

The majority of espresso statements are made up of four parts:

  1. Static Espresso method
  2. ViewMatchers
  3. ViewAction
  4. ViewAssertion

Let's examine the full test.

  1. Open TaskDetailFragmentTest.kt.
  2. Update the activeTaskDetails_DisplayedInUi test:

TaskDetailFragmentTest.kt

    @Test
    fun activeTaskDetails_DisplayedInUi() = runBlockingTest{
        // GIVEN - Add active (incomplete) task to the DB
        val activeTask = Task("Active Task", "AndroidX Rocks", false)
        repository.saveTask(activeTask)

        // WHEN - Details fragment launched to display task
        val bundle = TaskDetailFragmentArgs(activeTask.id).toBundle()
        launchFragmentInContainer<TaskDetailFragment>(bundle, R.style.AppTheme)

        // THEN - Task details are displayed on the screen
        // make sure that the title/description are both shown and correct
        onView(withId(R.id.task_detail_title_text)).check(matches(isDisplayed()))
        onView(withId(R.id.task_detail_title_text)).check(matches(withText("Active Task")))
        onView(withId(R.id.task_detail_description_text)).check(matches(isDisplayed()))
        onView(withId(R.id.task_detail_description_text)).check(matches(withText("AndroidX Rocks")))
        // and make sure the "active" checkbox is shown unchecked
        onView(withId(R.id.task_detail_complete_checkbox)).check(matches(isDisplayed()))
        onView(withId(R.id.task_detail_complete_checkbox)).check(matches(not(isChecked())))
    }

Here are the import statements if needed:

import androidx.test.espresso.Espresso.onView
import androidx.test.espresso.assertion.ViewAssertions.matches
import androidx.test.espresso.matcher.ViewMatchers.isChecked
import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
import androidx.test.espresso.matcher.ViewMatchers.withId
import androidx.test.espresso.matcher.ViewMatchers.withText
import org.hamcrest.core.IsNot.not

Everything after the // THEN comment uses Espresso.

  1. Run the test and confirm it passes.

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