@EnabledOnOs for OS-specific tests in JUnit - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable the test only on Windows OS.

JUnit

@EnabledOnOs([1])
void testWindowsFeature() {
    // test code here
}

Drag options to blanks, or click blank then click option'

AOS.WINDOWS

BOS.LINUX

COS.MAC

DOS.UNIX

Attempts:

3 left

💡 Hint

Common Mistakes

Using OS.LINUX or OS.MAC instead of OS.WINDOWS

Forgetting to use curly braces {} around the OS constant

The @EnabledOnOs annotation requires the OS constant to specify which OS the test should run on. For Windows, use OS.WINDOWS.

2fill in blank

medium

Complete the code to enable the test on both Linux and Mac OS.

JUnit

@EnabledOnOs([1])
void testUnixFeatures() {
    // test code here
}

Drag options to blanks, or click blank then click option'

AOS.LINUX

BOS.LINUX, OS.MAC

COS.MAC

DOS.WINDOWS

Attempts:

3 left

💡 Hint

Common Mistakes

Listing OS constants without braces

Using only one OS constant when multiple are needed

To enable the test on multiple OS, list them inside the annotation separated by commas within the braces.

3fill in blank

hard

Fix the error in the annotation to correctly enable the test on Mac OS.

JUnit

@EnabledOnOs([1])
void testMacFeature() {
    // test code here
}

Drag options to blanks, or click blank then click option'

AOS.MAC

BOS.mac

CMac.OS

DOS.Mac

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect casing like OS.mac or OS.Mac

Swapping the order like Mac.OS

The OS constants are case-sensitive and must be exactly OS.MAC to work correctly.

4fill in blank

hard

Fill both blanks to enable the test on Linux and Windows OS.

JUnit

@EnabledOnOs([1], [2] })
void testCrossPlatform() {
    // test code here
}

Drag options to blanks, or click blank then click option'

AOS.LINUX

BOS.WINDOWS

COS.MAC

DOS.UNIX

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of braces

Forgetting the comma between OS constants

To enable on multiple OS, list them inside the annotation separated by commas within braces. Here, Linux and Windows are OS.LINUX and OS.WINDOWS.

5fill in blank

hard

Fill all three blanks to enable the test on Windows, Mac, and Linux OS.

JUnit

@EnabledOnOs([1], [2], [3] })
void testAllPlatforms() {
    // test code here
}

Drag options to blanks, or click blank then click option'

AOS.WINDOWS

BOS.MAC

COS.LINUX

DOS.UNIX

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of braces

Missing commas between OS constants

Incorrect casing of OS constants

The annotation lists all OS constants inside braces separated by commas. For Windows, Mac, and Linux, use OS.WINDOWS, OS.MAC, and OS.LINUX.

Practice

1. What is the main purpose of the @EnabledOnOs annotation in JUnit?

easy

A. To specify the Java version for a test

B. To disable a test permanently

C. To run tests in parallel

D. To run a test only on specified operating systems

Solution

1. Step 1: Understand the role of @EnabledOnOs

   This annotation controls on which operating systems a test should run.

2. Step 2: Compare with other options

   Options B, C, and D describe different functionalities unrelated to OS-specific test execution.

3. Final Answer:

   To run a test only on specified operating systems -> Option D

4. Quick Check:

   @EnabledOnOs = Run test on specific OS [OK]

Hint: Think: runs tests only on chosen OS platforms [OK]

Common Mistakes:

• Confusing @EnabledOnOs with disabling tests
• Assuming it controls Java version
• Thinking it manages test parallelism

2. Which of the following is the correct syntax to enable a test only on Windows OS using @EnabledOnOs?

easy

A. @EnabledOnOs(OS.WINDOWS)

B. @EnabledOnOs(OS.WIN)

C. @EnabledOnOs("Windows")

D. @EnabledOnOs(os = "Windows")

Solution

1. Step 1: Recall the correct enum usage

   The @EnabledOnOs annotation uses the enum OS with constants like WINDOWS.

2. Step 2: Check each option's syntax

   @EnabledOnOs(OS.WINDOWS) uses the correct enum constant OS.WINDOWS. Options A, B, and C use invalid syntax or strings instead of enum constants.

3. Final Answer:

   @EnabledOnOs(OS.WINDOWS) -> Option A

4. Quick Check:

   Use enum OS.WINDOWS for Windows [OK]

Hint: Use enum OS constants, not strings or wrong names [OK]

Common Mistakes:

• Using string literals instead of enum constants
• Using incorrect enum names like OS.WIN
• Adding parameters incorrectly

3. Given the following test code snippet, what will happen when running on Linux OS?

@Test
@EnabledOnOs(OS.WINDOWS)
void testOnlyOnWindows() {
    System.out.println("Running Windows test");
}

medium

A. The test will run and print "Running Windows test"

B. The test will be skipped and not run

C. The test will fail with an exception

D. The test will run but print nothing

Solution

1. Step 1: Understand the annotation effect on Linux

   The test is enabled only on Windows OS, so on Linux it should not run.

2. Step 2: Determine test behavior on unsupported OS

   JUnit skips tests annotated with @EnabledOnOs if the current OS does not match.

3. Final Answer:

   The test will be skipped and not run -> Option B

4. Quick Check:

   Test runs only on Windows, skipped on Linux [OK]

Hint: If OS doesn't match, test is skipped automatically [OK]

Common Mistakes:

• Assuming test runs but prints nothing
• Expecting a failure or exception
• Thinking test runs on all OS by default

4. Identify the error in this test code snippet:

@Test
@EnabledOnOs(OS.LINUX, OS.MAC)
void testOnUnix() {
    // test code
}

medium

A. OS.LINUX and OS.MAC are invalid enum constants

B. The annotation should be @DisabledOnOs instead

C. Multiple OS values must be inside an array

D. The method must be static to use @EnabledOnOs

Solution

1. Step 1: Check annotation parameter format

   The @EnabledOnOs annotation expects an array of OS enums when specifying multiple OSes.

2. Step 2: Identify correct syntax

   Correct syntax is @EnabledOnOs({OS.LINUX, OS.MAC}). The code misses curly braces for the array. Thus, Multiple OS values must be inside an array correctly identifies that multiple OS values must be inside an array.

3. Final Answer:

   Multiple OS values must be inside an array -> Option C

4. Quick Check:

   Use curly braces for multiple OS enums [OK]

Hint: Use curly braces {} for multiple OS enums [OK]

Common Mistakes:

• Omitting curly braces for multiple OS values
• Confusing @EnabledOnOs with @DisabledOnOs
• Thinking method must be static

5. You want a test to run only on Windows and Mac OS but skip on Linux. Which is the correct way to write the @EnabledOnOs annotation for this requirement?

hard

A. @EnabledOnOs({OS.WINDOWS, OS.MAC})

B. @EnabledOnOs(OS.WINDOWS, OS.MAC, OS.LINUX)

C. @EnabledOnOs(OS.WINDOWS) @EnabledOnOs(OS.MAC)

D. @EnabledOnOs(OS.WINDOWS & OS.MAC)

Solution

1. Step 1: Understand how to specify multiple OSes

   Multiple OSes must be provided as an array inside curly braces in @EnabledOnOs.

2. Step 2: Evaluate each option

   @EnabledOnOs({OS.WINDOWS, OS.MAC}) correctly uses an array with OS.WINDOWS and OS.MAC. @EnabledOnOs(OS.WINDOWS, OS.MAC, OS.LINUX) includes Linux, which should be excluded. @EnabledOnOs(OS.WINDOWS) @EnabledOnOs(OS.MAC) uses multiple annotations, which is invalid. @EnabledOnOs(OS.WINDOWS & OS.MAC) uses an invalid bitwise operator.

3. Final Answer:

   @EnabledOnOs({OS.WINDOWS, OS.MAC}) -> Option A

4. Quick Check:

   Use array with OS enums to include multiple OSes [OK]

Hint: Use curly braces with OS enums for multiple OSes [OK]

Common Mistakes:

• Including unwanted OS like Linux
• Using multiple @EnabledOnOs annotations
• Using invalid operators like &