DiscoverFragmentTest.kt

package com.mobymagic.shazamclone.discover
import android.support.test.espresso.Espresso.onView
import android.support.test.espresso.action.ViewActions.click
import android.support.test.espresso.assertion.ViewAssertions.matches
import android.support.test.espresso.matcher.ViewMatchers.isDisplayed
import android.support.test.espresso.matcher.ViewMatchers.withId
import android.support.test.filters.LargeTest
import android.support.test.rule.ActivityTestRule
import android.support.test.runner.AndroidJUnit4
import com.mobymagic.shazamclone.R
import org.junit.Assert.*
import org.junit.Rule
import org.junit.Test
import org.junit.runner.RunWith

@RunWith(AndroidJUnit4::class)
// Usually UI tests are marked as large tests. Read more on this here: https://testing.googleblog.com/2010/12/test-sizes.html
@LargeTest
class DiscoverFragmentTest {
    
    // Instructs the Kotlin compiler not to generate getters/setters for this property and expose it as a field.
    @JvmField
    // By using ActivityTestRule, the testing framework launches the activity under test before each test method
    // annotated with @Test. The framework handles shutting down the activity after the test finishes
    @Rule
    val mDiscoverActivityTestRule = ActivityTestRule<DiscoverActivity>(DiscoverActivity::class.java)
    
    // Check that clicking the start button opens up the song detail page
    @Test
    fun clickStartIdentifyButtonOpensSongDetailPage() {
        // Click on the start button
        onView(withId(R.id.discoverStartIdentifyButton)).perform(click())
        // Check that the song detail view is shown afterwards
        onView(withId(R.id.songDetailFragmentContainer)).check(matches(isDisplayed()))
    }
    
    // Check that clicking the donate button opens the donate page
    @Test
    fun clickDonateButtonOpensDonatePage() {
        // Click on the donate button
        onView(withId(R.id.discoverDonateButton)).perform(click())
        // Check that the donate view is shown afterwards
        onView(withId(R.id.donateFragmentContainer)).check(matches(isDisplayed()))
    }
    
    // Check that clicking the history button opens the history page
    @Test
    fun clickHistoryButtonOpensHistoryPage() {
        // Click on the history button
        onView(withId(R.id.discoverHistoryButton)).perform(click())
        // Check that the history view is shown afterwards
        onView(withId(R.id.historyFragmentContainer)).check(matches(isDisplayed()))
    }
}