Add tests for MainActivity

app/src/androidTest/java/li/dadada/uuidgen/ui/MainActivityTest.kt

@@ -0,0 +1,38 @@
+package li.dadada.uuidgen.ui
+
+import androidx.fragment.app.testing.launchFragmentInContainer
+import androidx.navigation.NavController
+import androidx.navigation.Navigation
+import androidx.navigation.testing.TestNavHostController
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.action.ViewActions.click
+import androidx.test.espresso.matcher.ViewMatchers
+import li.dadada.uuidgen.R
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Assert.*
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class MainActivityTest {
+
+    @Test
+    fun testOnOptionsItemSelected() {
+        val navController: NavController =
+            TestNavHostController(ApplicationProvider.getApplicationContext())
+        navController.setGraph(R.navigation.nav_graph)
+
+        val scenario = launchFragmentInContainer<UuidGenFragment>()
+
+        // Set the NavController property on the fragment
+        scenario.onFragment { fragment ->
+            Navigation.setViewNavController(fragment.requireView(), navController)
+
+            // Verify that performing a click changes the NavController’s state
+            onView(ViewMatchers.withId(R.id.action_history)).perform(click())
+        }
+        assertEquals(navController.currentDestination?.id, R.id.uuid_list_fragment)
+    }
+}