Test Navigation Component

app/build.gradle

@@ -61,4 +61,9 @@ dependencies {
     implementation "androidx.constraintlayout:constraintlayout:$constraintlayout_version"
     implementation "androidx.navigation:navigation-fragment-ktx:$nav_version"
     implementation "androidx.navigation:navigation-ui-ktx:$nav_version"
+
+    androidTestImplementation 'com.android.support.test.espresso:espresso-contrib:3.4.0'
+    androidTestImplementation 'androidx.navigation:navigation-testing:2.4.2'
+
+    debugImplementation 'androidx.fragment:fragment-testing:1.4.1'
 }
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app/src/androidTest/java/com/example/wordsapp/NavigationTests.kt

+package com.example.wordsapp
+
+import androidx.fragment.app.testing.launchFragmentInContainer
+import androidx.navigation.Navigation
+import androidx.navigation.testing.TestNavHostController
+import androidx.recyclerview.widget.RecyclerView
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.action.ViewActions.click
+import androidx.test.espresso.contrib.RecyclerViewActions
+import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.runner.AndroidJUnit4
+import junit.framework.Assert.assertEquals
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class NavigationTests {
+    @Test
+    fun navigate_to_words_nav_component() {
+        val navController = TestNavHostController(
+            ApplicationProvider.getApplicationContext()
+        )
+        val letterListScenario = launchFragmentInContainer<LetterListFragment>(
+            themeResId =
+            R.style.Theme_Words
+        )
+
+        letterListScenario.onFragment { fragment ->
+
+            navController.setGraph(R.navigation.nav_graph)
+
+            Navigation.setViewNavController(fragment.requireView(), navController)
+        }
+
+        onView(withId(R.id.recycler_view))
+            .perform(
+                RecyclerViewActions
+                    .actionOnItemAtPosition<RecyclerView.ViewHolder>(2, click())
+            )
+
+        assertEquals(navController.currentDestination?.id, R.id.wordListFragment)
+    }
+}
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