Compose UI testing in Android Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Compose UI testing used for?

Compose UI testing is used to check if your app's user interface works correctly by simulating user actions and verifying UI elements.

beginner

Which Compose testing function finds a UI element by its text?

The function composeTestRule.onNodeWithText("text") finds a UI element that displays the given text.

beginner

What does performClick() do in Compose UI testing?

It simulates a user clicking or tapping on a UI element during a test.

beginner

Why use assertIsDisplayed() in Compose UI tests?

To check that a UI element is visible on the screen, ensuring it appears as expected to the user.

beginner

How do you set up a Compose UI test rule in Kotlin?

Use @get:Rule val composeTestRule = createComposeRule() to create a test environment for Compose UI tests.

Which function finds a UI element by its content description in Compose UI testing?

A onNodeWithContentDescription()

B onNodeWithTag()

C onNodeWithText()

D onNodeWithId()

Use onNodeWithContentDescription() to find elements by their content description, which helps with accessibility.

What does assertIsDisplayed() check in a Compose UI test?

A If the element has focus

B If the element is clickable

C If the element is enabled

D If the element is visible on screen

assertIsDisplayed() verifies that the UI element is visible to the user.

How do you simulate a user typing text in a Compose UI test?

A performClick()

B performScroll()

C performTextInput()

D performLongClick()

performTextInput() simulates typing text into a text field.

What is the purpose of createComposeRule() in Compose UI testing?

A To create a UI element

B To set up the Compose test environment

C To launch the app

D To run unit tests

createComposeRule() sets up the environment needed to run Compose UI tests.

Which Compose test function would you use to find a UI element by a test tag?

A onNodeWithTag()

B onNodeWithContentDescription()

C onNodeWithText()

D onNodeWithId()

onNodeWithTag() finds UI elements marked with a specific test tag.

Explain how to write a simple Compose UI test that checks if a button with text "Click me" is visible and can be clicked.

Think about how you find UI elements and simulate user actions in Compose tests.

Describe the role of test tags in Compose UI testing and how they help find UI elements.

Imagine you want to find a button that has no text but you gave it a special tag.

Practice

1. What is the main purpose of createComposeRule() in Compose UI testing?

easy

A. To create UI elements dynamically during runtime

B. To set up the environment for testing Compose UI components

C. To launch the app on a physical device

D. To generate random test data for UI tests

Solution

1. Step 1: Understand the role of createComposeRule()

   This function sets up the Compose testing environment so you can test UI components safely and isolated.

2. Step 2: Differentiate from other options

   It does not create UI elements dynamically, launch apps, or generate test data; it only prepares the test rule.

3. Final Answer:

   To set up the environment for testing Compose UI components -> Option B

4. Quick Check:

   Compose test setup = B [OK]

Hint: Remember: createComposeRule sets up Compose test environment [OK]

Common Mistakes:

• Thinking it creates UI elements during app runtime
• Confusing it with launching the app on devices
• Assuming it generates test data automatically

2. Which of the following is the correct way to find a UI element by its text in Compose UI testing?

easy

A. composeTestRule.getElementByText("Hello")

B. composeTestRule.findViewByText("Hello")

C. composeTestRule.selectNode("Hello")

D. composeTestRule.onNodeWithText("Hello")

Solution

1. Step 1: Recall Compose testing API for text search

   The correct method to find a node by text is onNodeWithText().

2. Step 2: Verify other options are invalid

   Methods like findViewByText, getElementByText, and selectNode do not exist in Compose testing.

3. Final Answer:

   composeTestRule.onNodeWithText("Hello") -> Option D

4. Quick Check:

   Find by text = onNodeWithText [OK]

Hint: Use onNodeWithText to find text elements in Compose tests [OK]

Common Mistakes:

• Using Android View testing methods instead of Compose methods
• Trying to use non-existent functions
• Confusing node selectors with view selectors

3. Given this Compose test code snippet:

composeTestRule.setContent {
  Text("Welcome")
}

composeTestRule.onNodeWithText("Welcome").assertExists()

What will happen when this test runs?

medium

A. The test will pass because the text "Welcome" exists

B. The test will fail because the text is not found

C. The test will throw a syntax error

D. The test will pass but not check the text

Solution

1. Step 1: Analyze the UI content set

   The UI contains a Text composable with the string "Welcome".

2. Step 2: Understand the assertion

   assertExists() checks that the node with text "Welcome" is present, which it is.

3. Final Answer:

   The test will pass because the text "Welcome" exists -> Option A

4. Quick Check:

   Text present means assertExists passes [OK]

Hint: assertExists passes if UI text is present exactly [OK]

Common Mistakes:

• Assuming assertExists checks content correctness beyond presence
• Thinking the test fails if no interaction is done
• Confusing syntax errors with runtime test failures

4. Identify the error in this Compose UI test code:

composeTestRule.setContent {
  Button(onClick = {}) {
    Text("Click Me")
  }
}

composeTestRule.onNodeWithTag("button").performClick()

medium

A. performClick() is not a valid Compose test function

B. The Button composable cannot be clicked in tests

C. The node is searched by tag but no tag was set on the Button

D. The Text inside Button should be searched instead of Button

Solution

1. Step 1: Check how the node is found

   The test looks for a node with tag "button" but the Button has no tag set.

2. Step 2: Understand Compose testing tags

   To find by tag, the Button must have Modifier.testTag("button") applied, which is missing.

3. Final Answer:

   The node is searched by tag but no tag was set on the Button -> Option C

4. Quick Check:

   Missing testTag causes node not found [OK]

Hint: Always add testTag modifier to find nodes by tag [OK]

Common Mistakes:

• Assuming performClick works without correct node selection
• Searching text inside Button instead of Button itself
• Thinking performClick is invalid in Compose tests

5. You want to test a Compose screen with a list of items. Each item has a unique test tag like "item_1", "item_2", etc. Which approach correctly verifies that the item with tag "item_3" is displayed and clickable?

hard

A. composeTestRule.onNodeWithTag("item_3").assertIsDisplayed().performClick()

B. composeTestRule.onNodeWithText("item_3").assertIsDisplayed().performClick()

C. composeTestRule.onNodeWithTag("item_3").assertExists().performClick()

D. composeTestRule.onNodeWithContentDescription("item_3").assertIsDisplayed().performClick()

Solution

1. Step 1: Identify correct node selector for test tag

   Use onNodeWithTag("item_3") to find the node by its unique test tag.

2. Step 2: Verify visibility and interaction

   assertIsDisplayed() confirms the node is visible, and performClick() simulates a click.

3. Step 3: Eliminate incorrect options

   Searching by text or content description is wrong here; assertExists() alone doesn't check visibility.

4. Final Answer:

   composeTestRule.onNodeWithTag("item_3").assertIsDisplayed().performClick() -> Option A

5. Quick Check:

   Tag + visible + click = composeTestRule.onNodeWithTag("item_3").assertIsDisplayed().performClick() [OK]

Hint: Use onNodeWithTag + assertIsDisplayed before performClick [OK]

Common Mistakes:

• Using onNodeWithText instead of onNodeWithTag for tags
• Skipping assertIsDisplayed before clicking
• Confusing content description with test tag