test: add more bottom nav tests

Signed-off-by: Aditya Wasan <adityawasan55@gmail.com>

app/src/androidTest/java/dev/msfjarvis/lobsters/ui/Theme.kt

@@ -0,0 +1,22 @@
+package dev.msfjarvis.lobsters.ui
+
+import androidx.compose.material.MaterialTheme
+import androidx.compose.runtime.Composable
+import dev.msfjarvis.lobsters.ui.theme.darkColors
+import dev.msfjarvis.lobsters.ui.theme.lightColors
+
+@Composable
+fun LightTestTheme(children: @Composable () -> Unit) {
+  MaterialTheme(
+    colors = lightColors,
+    content = children,
+  )
+}
+
+@Composable
+fun DarkTestTheme(children: @Composable () -> Unit) {
+  MaterialTheme(
+    colors = darkColors,
+    content = children,
+  )
+}

app/src/androidTest/java/dev/msfjarvis/lobsters/ui/navigation/LobstersBottomNavTest.kt

@@ -1,10 +1,18 @@
 package dev.msfjarvis.lobsters.ui.navigation
 
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.graphics.asAndroidBitmap
+import androidx.compose.ui.test.assertHasClickAction
 import androidx.compose.ui.test.captureToImage
 import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.test.onNodeWithTag
 import androidx.compose.ui.test.onRoot
+import androidx.compose.ui.test.performClick
 import com.karumi.shot.ScreenshotTest
+import dev.msfjarvis.lobsters.ui.DarkTestTheme
 import dev.msfjarvis.lobsters.ui.main.LobstersBottomNav
 import dev.msfjarvis.lobsters.ui.theme.LobstersTheme
 import org.junit.Rule
@@ -18,7 +26,7 @@ class LobstersBottomNavTest : ScreenshotTest {
   @Test
   fun bottomNavIsRenderedCorrectlyOnScreen() {
     composeTestRule.setContent {
-      LobstersTheme {
+      DarkTestTheme {
         LobstersBottomNav(
           currentDestination = Destination.startDestination,
           navigateToDestination = { /*TODO*/ },
@@ -29,4 +37,28 @@ class LobstersBottomNavTest : ScreenshotTest {
 
     compareScreenshot(composeTestRule.onRoot().captureToImage().asAndroidBitmap())
   }
+
+  @Test
+  fun bottomNavUpdatesCorrectly() {
+    composeTestRule.setContent {
+      DarkTestTheme {
+        var destination by remember { mutableStateOf(Destination.startDestination) }
+
+        LobstersBottomNav(
+          currentDestination = destination,
+          navigateToDestination = { newDestination -> destination = newDestination },
+          jumpToIndex = { /*TODO*/ }
+        )
+      }
+    }
+
+    selectNode(Destination.Saved.name)
+
+    compareScreenshot(composeTestRule.onRoot().captureToImage().asAndroidBitmap())
+  }
+
+  private fun selectNode(testTag: String) = composeTestRule
+    .onNodeWithTag(testTag)
+    .assertHasClickAction()
+    .performClick()
 }

app/src/androidTest/java/dev/msfjarvis/lobsters/ui/posts/LobstersItemTest.kt

@@ -5,7 +5,7 @@ import androidx.compose.ui.test.captureToImage
 import androidx.compose.ui.test.junit4.createComposeRule
 import androidx.compose.ui.test.onRoot
 import com.karumi.shot.ScreenshotTest
-import dev.msfjarvis.lobsters.ui.theme.LobstersTheme
+import dev.msfjarvis.lobsters.ui.DarkTestTheme
 import org.junit.Rule
 import org.junit.Test
 
@@ -17,7 +17,7 @@ class LobstersItemTest : ScreenshotTest {
   @Test
   fun postsAreRenderedCorrectlyOnScreen() {
     composeTestRule.setContent {
-      LobstersTheme {
+      DarkTestTheme {
         LobstersItem(
           post = TEST_POST,
           onClick = { /*TODO*/ },

app/src/main/java/dev/msfjarvis/lobsters/ui/main/LobstersApp.kt

@@ -100,6 +100,7 @@ fun LobstersBottomNav(
         },
         label = { Text(stringResource(id = screen.labelRes)) },
         selected = currentDestination == screen,
+        modifier = Modifier.testTag(screen.name),
         alwaysShowLabel = false,
         onClick = {
           if (screen != currentDestination) {