Test suites with @Suite in JUnit - Test Execution Trace

Test Overview

This test suite groups two simple test classes using JUnit's @Suite annotation. It verifies that all tests in the suite run and pass successfully.

Test Code - JUnit 5

JUnit

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertTrue;

public class TestClassOne {
    @Test
    void testOne() {
        assertTrue(1 + 1 == 2);
    }
}

public class TestClassTwo {
    @Test
    void testTwo() {
        assertTrue("hello".startsWith("h"));
    }
}

import org.junit.platform.suite.api.SelectClasses;
import org.junit.platform.suite.api.Suite;

@Suite
@SelectClasses({TestClassOne.class, TestClassTwo.class})
public class MyTestSuite {
    // This class remains empty, used only as a holder for the above annotations
}

Execution Trace - 4 Steps

Step	Action	System State	Assertion	Result
1	Test runner starts and loads MyTestSuite class	JUnit test runner initialized with suite containing TestClassOne and TestClassTwo	—	PASS
2	Test runner executes TestClassOne.testOne()	TestClassOne loaded, testOne method ready to run	assertTrue(1 + 1 == 2) verifies 2 equals 2	PASS
3	Test runner executes TestClassTwo.testTwo()	TestClassTwo loaded, testTwo method ready to run	assertTrue("hello".startsWith("h")) verifies string starts with 'h'	PASS
4	Test runner completes execution of all tests in suite	All tests in MyTestSuite executed	All assertions passed	PASS

Failure Scenario

Failing Condition: One of the test methods in the suite fails its assertion

Execution Trace Quiz - 3 Questions

What does the @Suite annotation do in this test code?

A Groups multiple test classes to run together as one suite

B Marks a single test method to be skipped

C Defines a test class as a parameterized test

D Specifies the order of test execution inside a class

Key Result

Using @Suite in JUnit helps organize multiple test classes to run together, making it easier to manage related tests and see combined results.

Practice

1. What is the main purpose of using @Suite in JUnit testing?

easy

A. To group multiple test classes to run together as one unit

B. To mark a method as a test case

C. To ignore a test class during execution

D. To specify the order of test methods within a class

Solution

1. Step 1: Understand the role of @Suite

   @Suite is an annotation used to create a test suite that groups multiple test classes.

2. Step 2: Compare with other annotations

   @Test marks methods as tests, @Ignore skips tests, and ordering is handled differently, so these do not match @Suite's purpose.

3. Final Answer:

   To group multiple test classes to run together as one unit -> Option A

4. Quick Check:

   @Suite groups classes = B [OK]

Hint: Remember: @Suite groups classes, not individual tests [OK]

Common Mistakes:

• Confusing @Suite with @Test annotation
• Thinking @Suite controls test method order
• Assuming @Suite skips tests

2. Which of the following is the correct way to declare a JUnit 5 test suite using @Suite and @SelectClasses?

easy

A. @Suite
@SelectClasses({TestA.class, TestB.class})
public class AllTests {}

B. @SuiteClasses({TestA.class, TestB.class})
public class AllTests {}

C. @RunWith(Suite.class)
@SuiteClasses({TestA.class, TestB.class})
public class AllTests {}

D. @TestSuite
@SelectClasses({TestA.class, TestB.class})
public class AllTests {}

Solution

1. Step 1: Identify JUnit 5 suite syntax

   JUnit 5 uses @Suite and @SelectClasses annotations together to define a suite.

2. Step 2: Check other options for JUnit 4 syntax or invalid annotations

   @RunWith and @SuiteClasses are JUnit 4 style; @TestSuite is invalid.

3. Final Answer:

   @Suite @SelectClasses({TestA.class, TestB.class}) public class AllTests {} -> Option A

4. Quick Check:

   JUnit 5 suite = @Suite + @SelectClasses [OK]

Hint: JUnit 5 suites use @Suite and @SelectClasses together [OK]

Common Mistakes:

• Using JUnit 4 annotations in JUnit 5 code
• Misspelling @SelectClasses
• Omitting the public class declaration

3. Given the following test suite code, what will happen when you run AllTests?

@Suite
@SelectClasses({TestOne.class, TestTwo.class})
public class AllTests {}

medium

A. Only TestTwo's tests will run

B. Both TestOne and TestTwo classes will run all their test methods

C. Only TestOne's tests will run

D. No tests will run because the suite class is empty

Solution

1. Step 1: Understand @SelectClasses effect

   @SelectClasses lists test classes to include in the suite; all their tests run.

2. Step 2: Confirm suite class content is irrelevant

   The suite class itself is a container; it does not need test methods to run included tests.

3. Final Answer:

   Both TestOne and TestTwo classes will run all their test methods -> Option B

4. Quick Check:

   @SelectClasses runs all listed classes [OK]

Hint: Suite runs all classes listed in @SelectClasses [OK]

Common Mistakes:

• Thinking suite class must have test methods
• Assuming only first class runs
• Believing empty suite class means no tests

4. Identify the error in this JUnit 5 test suite declaration:

@Suite
@SelectClasses({TestA.class, TestB.class})
public void AllTests() {}

medium

A. Suite class must extend a base test class

B. Missing @Test annotation on AllTests method

C. @SelectClasses cannot include multiple classes

D. Suite class should not be a method; it must be a class declaration

Solution

1. Step 1: Check the suite declaration syntax

   The suite must be a class, not a method. Here, 'public void AllTests()' is a method.

2. Step 2: Validate other options

   @Test is not needed on suite, @SelectClasses supports multiple classes, and no inheritance is required.

3. Final Answer:

   Suite class should not be a method; it must be a class declaration -> Option D

4. Quick Check:

   Suite must be a class, not a method [OK]

Hint: Suite must be a class, not a method [OK]

Common Mistakes:

• Writing suite as a method instead of a class
• Adding unnecessary @Test to suite
• Thinking suite must extend another class

5. You want to create a test suite that runs LoginTests, PaymentTests, and LogoutTests classes. Which of the following is the best way to write this suite in JUnit 5?

hard

A. @Suite
@SelectPackages({"com.example.tests"})
public class FullSuite {}

B. @SuiteClasses({LoginTests.class, PaymentTests.class, LogoutTests.class})
public class FullSuite {}

C. @Suite
@SelectClasses({LoginTests.class, PaymentTests.class, LogoutTests.class})
public class FullSuite {}

D. @RunWith(Suite.class)
@SelectClasses({LoginTests.class, PaymentTests.class, LogoutTests.class})
public class FullSuite {}

Solution

1. Step 1: Use correct JUnit 5 annotations

   JUnit 5 uses @Suite and @SelectClasses to specify test classes in a suite.

2. Step 2: Evaluate other options

   @SuiteClasses and @RunWith are JUnit 4 style; @SelectPackages is for packages, not specific classes.

3. Final Answer:

   @Suite @SelectClasses({LoginTests.class, PaymentTests.class, LogoutTests.class}) public class FullSuite {} -> Option C

4. Quick Check:

   JUnit 5 suite = @Suite + @SelectClasses [OK]

Hint: Use @Suite with @SelectClasses listing all test classes [OK]

Common Mistakes:

• Mixing JUnit 4 and 5 annotations
• Using @SelectPackages when classes are needed
• Omitting public class declaration