@Order for execution order in JUnit - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Test execution order with @Order annotation

Given the following JUnit 5 test class, what is the order of test method execution?

JUnit

import org.junit.jupiter.api.*;
import org.junit.jupiter.api.MethodOrderer.OrderAnnotation;

@TestMethodOrder(OrderAnnotation.class)
public class SampleTest {

    @Test
    @Order(2)
    void testSecond() {
        System.out.println("Second");
    }

    @Test
    @Order(1)
    void testFirst() {
        System.out.println("First");
    }

    @Test
    @Order(3)
    void testThird() {
        System.out.println("Third");
    }
}

A First, Second, Third

B Second, First, Third

C Third, Second, First

D Execution order is random

💡 Hint

Look at the @Order values and the @TestMethodOrder annotation.

JUnit 5 executes test methods in the order specified by the @Order annotation when @TestMethodOrder(OrderAnnotation.class) is used. Lower order values run first.

❓ assertion

intermediate

Assertion to verify test execution order

Which assertion correctly verifies that a list of executed test names matches the expected order when using @Order annotation?

JUnit

List<String> executedTests = List.of("testFirst", "testSecond", "testThird");
List<String> expectedOrder = List.of("testFirst", "testSecond", "testThird");

A assertArrayEquals(expectedOrder.toArray(), executedTests.toArray());

B assertEquals(expectedOrder, executedTests);

C assertTrue(executedTests.containsAll(expectedOrder));

D assertNotNull(executedTests);

💡 Hint

Check which assertion verifies both order and content equality.

assertArrayEquals compares arrays element by element and order matters. assertEquals on lists also works but assertArrayEquals is more explicit for order verification.

🔧 Debug

advanced

Why is @Order ignored in this test class?

Consider this JUnit 5 test class: import org.junit.jupiter.api.*; public class TestClass { @Test @Order(1) void testA() {} @Test @Order(2) void testB() {} } Why are the tests not executed in the order testA then testB?

A Because @Order values must be unique

B Because @Order annotation is only for JUnit 4

C Because test methods must be static to use @Order

D Because @TestMethodOrder(OrderAnnotation.class) is missing on the class

💡 Hint

Check if the class has the annotation that enables ordering by @Order.

JUnit 5 requires @TestMethodOrder(OrderAnnotation.class) on the test class to enable ordering by @Order annotations. Without it, the order is not guaranteed.

🧠 Conceptual

advanced

Effect of duplicate @Order values

What happens if two test methods in a JUnit 5 test class have the same @Order value when using @TestMethodOrder(OrderAnnotation.class)?

A JUnit runs tests alphabetically ignoring @Order

B JUnit throws a runtime exception and stops execution

C Tests with the same order value run in an undefined order relative to each other

D Tests with duplicate order values are skipped

💡 Hint

Think about how ordering works when priorities are equal.

When multiple tests have the same @Order value, their relative order is not guaranteed and may be arbitrary.

❓ framework

expert

Combining @Order with other TestMethodOrderers

Given a JUnit 5 test class annotated with @TestMethodOrder(MethodOrderer.OrderAnnotation.class), what happens if a test method is missing the @Order annotation?

A The test method is executed before all methods with @Order annotations

B JUnit throws an exception and fails the test run

C The test method is executed after all methods with @Order annotations

D The test method is ignored and not executed

💡 Hint

The default @Order value is 0, and lower values run first.

JUnit assigns a default order value of 0 to test methods without @Order annotation. Since lower order values are executed first, they run before test methods with explicitly assigned higher order values.

Practice

1. What does the @Order annotation do in JUnit testing?

easy

A. It sets the order in which test methods are executed.

B. It skips the annotated test method during execution.

C. It marks a test method as disabled.

D. It repeats the test method multiple times.

Solution

1. Step 1: Understand the purpose of @Order

   The @Order annotation is used to specify the sequence in which test methods run.

2. Step 2: Compare with other options

   Skipping, disabling, or repeating tests are done by other annotations like @Disabled or loops, not @Order.

3. Final Answer:

   It sets the order in which test methods are executed. -> Option A

4. Quick Check:

   @Order controls test execution order [OK]

Hint: Remember: @Order controls test run sequence [OK]

Common Mistakes:

• Confusing @Order with @Disabled
• Thinking @Order repeats tests
• Assuming @Order skips tests

2. Which annotation must be added to a JUnit test class to enable @Order annotations on its methods?

easy

A. @TestMethodOrder(OrderAnnotation.class)

B. @TestOrder

C. @OrderEnabled

D. @EnableOrder

Solution

1. Step 1: Recall the class-level annotation for ordering

   JUnit requires @TestMethodOrder(OrderAnnotation.class) on the test class to activate @Order on methods.

2. Step 2: Verify other options

   Options B, C, and D are not valid JUnit annotations.

3. Final Answer:

   @TestMethodOrder(OrderAnnotation.class) -> Option A

4. Quick Check:

   Enable ordering with @TestMethodOrder(OrderAnnotation.class) [OK]

Hint: Use @TestMethodOrder(OrderAnnotation.class) to activate @Order [OK]

Common Mistakes:

• Using non-existent annotations like @TestOrder
• Forgetting to add @TestMethodOrder on class
• Confusing method-level and class-level annotations

3. Given the following JUnit test class, in what order will the test methods run?

@TestMethodOrder(OrderAnnotation.class)
class SampleTest {
  @Test
  @Order(2)
  void testB() {}

  @Test
  @Order(1)
  void testA() {}

  @Test
  @Order(3)
  void testC() {}
}

medium

A. testB, testC, testA

B. testA, testB, testC

C. testC, testB, testA

D. testB, testA, testC

Solution

1. Step 1: Identify the order values

   testA has @Order(1), testB has @Order(2), testC has @Order(3).

2. Step 2: Arrange tests by ascending order

   Tests run from lowest to highest order number: testA, testB, then testC.

3. Final Answer:

   testA, testB, testC -> Option B

4. Quick Check:

   Lower @Order number runs first [OK]

Hint: Lower @Order number runs before higher [OK]

Common Mistakes:

• Assuming declaration order matters over @Order
• Mixing up ascending and descending order
• Ignoring @TestMethodOrder annotation

4. What is wrong with this JUnit test class if the tests do not run in the expected order?

class MyTests {
  @Test
  @Order(1)
  void firstTest() {}

  @Test
  @Order(2)
  void secondTest() {}
}

medium

A. @Order values must start from 0, not 1.

B. Test methods must be static to use @Order.

C. @Order annotation cannot be used with @Test.

D. Missing @TestMethodOrder(OrderAnnotation.class) on the class.

Solution

1. Step 1: Check class-level annotation

   The class lacks @TestMethodOrder(OrderAnnotation.class), so @Order annotations are ignored.

2. Step 2: Verify other options

   @Order values can start at 1, @Order works with @Test, and test methods do not need to be static.

3. Final Answer:

   Missing @TestMethodOrder(OrderAnnotation.class) on the class. -> Option D

4. Quick Check:

   Class must have @TestMethodOrder to enable @Order [OK]

Hint: Add @TestMethodOrder(OrderAnnotation.class) on class to enable ordering [OK]

Common Mistakes:

• Forgetting class-level @TestMethodOrder annotation
• Thinking @Order needs static methods
• Believing @Order values must start at zero

5. You have a JUnit test class with methods annotated with @Order values 1, 2, and 2. What will happen when you run the tests with @TestMethodOrder(OrderAnnotation.class)?

hard

A. Tests with duplicate order values are skipped.

B. JUnit throws a runtime error due to duplicate order values.

C. Tests with the same order value run in declaration order among themselves.

D. Tests run in random order ignoring the duplicate values.

Solution

1. Step 1: Understand behavior with duplicate @Order values

   JUnit allows duplicate order values; tests with the same order run in the order they appear in the code.

2. Step 2: Check other options

   JUnit does not throw errors or skip tests due to duplicate order values, nor does it randomize them.

3. Final Answer:

   Tests with the same order value run in declaration order among themselves. -> Option C

4. Quick Check:

   Duplicate @Order runs in code order [OK]

Hint: Duplicate @Order runs in source code order [OK]

Common Mistakes:

• Expecting errors on duplicate @Order values
• Assuming tests with same order run randomly
• Thinking duplicates cause tests to skip