test: add UI tests for TopAppBar

app/src/androidTest/java/com/android/periodpals/ui/navigation/TopAppBarTest.kt

@@ -0,0 +1,52 @@
+package com.android.periodpals.ui.navigation
+
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.junit4.createComposeRule
+import androidx.compose.ui.test.onNodeWithTag
+import androidx.compose.ui.test.performClick
+import org.junit.Rule
+import org.junit.Test
+
+class TopAppBarTest {
+
+  @get:Rule val composeTestRule = createComposeRule()
+
+  @Test
+  fun topAppBar_displaysTitle() {
+    composeTestRule.setContent { TopAppBar(title = "Tampon Timer") }
+
+    composeTestRule.onNodeWithTag("topBar").assertIsDisplayed()
+    composeTestRule.onNodeWithTag("screenTitle").assertIsDisplayed()
+  }
+
+  @Test
+  fun topAppBar_displaysBackButton() {
+    composeTestRule.setContent { TopAppBar(title = "Tampon Timer", backButton = true) }
+
+    composeTestRule.onNodeWithTag("topBar").assertIsDisplayed()
+    composeTestRule.onNodeWithTag("goBackButton").assertIsDisplayed()
+  }
+
+  @Test
+  fun topAppBar_backButtonClick() {
+    var backButtonClicked = false
+
+    composeTestRule.setContent {
+      TopAppBar(
+          title = "Tampon Timer",
+          backButton = true,
+          onBackButtonClick = { backButtonClicked = true })
+    }
+
+    composeTestRule.onNodeWithTag("goBackButton").performClick()
+    assert(backButtonClicked)
+  }
+
+  @Test
+  fun topAppBar_noBackButton() {
+    composeTestRule.setContent { TopAppBar(title = "Tampon Timer", backButton = false) }
+
+    composeTestRule.onNodeWithTag("topBar").assertIsDisplayed()
+    composeTestRule.onNodeWithTag("goBackButton").assertDoesNotExist()
+  }
+}