@TestInstance(Lifecycle.PER_CLASS)

When using @TestInstance(Lifecycle.PER_CLASS):

• A single instance of the test class is created and shared across all test methods
• Instance variables maintain state between test methods
• @BeforeAll and @AfterAll methods can be non-static
• Useful for expensive setup or when you need to maintain state

Example - PER_CLASS Shared Instance

package com.logicbig.example;

import org.junit.jupiter.api.*;

@TestInstance(TestInstance.Lifecycle.PER_CLASS)
public class TestInstancePerClassTest {

    private int counter = 0;

    @BeforeAll
    void beforeAll() {
        System.out.println("BeforeAll - Instance: " + this);
        System.out.println("BeforeAll - Counter initialized to: " + counter);
    }

    @BeforeEach
    void beforeEach() {
        System.out.println("BeforeEach - Counter before test: " + counter);
    }

    @Test
    void testMethod1() {
        counter++;
        System.out.println("TestMethod1 - Counter: " + counter);
        System.out.println("TestMethod1 - Instance: " + this);
    }

    @Test
    void testMethod2() {
        counter++;
        System.out.println("TestMethod2 - Counter: " + counter);
        System.out.println("TestMethod2 - Instance: " + this);
    }

    @Test
    void testMethod3() {
        counter++;
        System.out.println("TestMethod3 - Counter: " + counter);
        System.out.println("TestMethod3 - Instance: " + this);
    }

    @AfterEach
    void afterEach() {
        System.out.println("AfterEach - Counter after test: " + counter);
    }

    @AfterAll
    void afterAll() {
        System.out.println("AfterAll - Final counter: " + counter);
        System.out.println("AfterAll - Instance: " + this);
    }
}

mvn test -Dtest=TestInstancePerClassTest

Output

D:\example-projects\junit-5\test-instance\junit-5-test-instance-per-class>mvn test -Dtest=TestInstancePerClassTest
[INFO] Scanning for projects...
[INFO] 
[INFO] --------< com.logicbig.example:junit-5-test-instance-per-class >--------
[INFO] Building junit-5-test-instance-per-class 1.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- resources:3.3.1:resources (default-resources) @ junit-5-test-instance-per-class ---
[WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory D:\example-projects\junit-5\test-instance\junit-5-test-instance-per-class\src\main\resources
[INFO] 
[INFO] --- compiler:3.11.0:compile (default-compile) @ junit-5-test-instance-per-class ---
[INFO] No sources to compile
[INFO] 
[INFO] --- resources:3.3.1:testResources (default-testResources) @ junit-5-test-instance-per-class ---
[WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory D:\example-projects\junit-5\test-instance\junit-5-test-instance-per-class\src\test\resources
[INFO] 
[INFO] --- compiler:3.11.0:testCompile (default-testCompile) @ junit-5-test-instance-per-class ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] --- surefire:3.2.5:test (default-test) @ junit-5-test-instance-per-class ---
[INFO] Using auto detected provider org.apache.maven.surefire.junitplatform.JUnitPlatformProvider
[INFO] 
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.logicbig.example.TestInstancePerClassTest
BeforeAll - Instance: com.logicbig.example.TestInstancePerClassTest@27ce24aa
BeforeAll - Counter initialized to: 0
BeforeEach - Counter before test: 0
TestMethod1 - Counter: 1
TestMethod1 - Instance: com.logicbig.example.TestInstancePerClassTest@27ce24aa
AfterEach - Counter after test: 1
BeforeEach - Counter before test: 1
TestMethod2 - Counter: 2
TestMethod2 - Instance: com.logicbig.example.TestInstancePerClassTest@27ce24aa
AfterEach - Counter after test: 2
BeforeEach - Counter before test: 2
TestMethod3 - Counter: 3
TestMethod3 - Instance: com.logicbig.example.TestInstancePerClassTest@27ce24aa
AfterEach - Counter after test: 3
AfterAll - Final counter: 3
AfterAll - Instance: com.logicbig.example.TestInstancePerClassTest@27ce24aa
[INFO] Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.100 s -- in com.logicbig.example.TestInstancePerClassTest
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 3, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  2.830 s
[INFO] Finished at: 2025-12-05T14:05:52+08:00
[INFO] ------------------------------------------------------------------------

With PER_CLASS, the same instance is used for all test methods, so the counter increments across tests.

Example Project

Dependencies and Technologies Used:

• junit-jupiter-engine 6.0.1 (Module "junit-jupiter-engine" of JUnit)
   Version Compatibility: 5.0.0 - 6.0.1Version List
  ×

  Version compatibilities of junit-jupiter-engine with this example:

  • 5.0.0
  • 5.0.1
  • 5.0.2
  • 5.0.3
  • 5.1.0
  • 5.1.1
  • 5.2.0
  • 5.3.0
  • 5.3.1
  • 5.3.2
  • 5.4.0
  • 5.4.1
  • 5.4.2
  • 5.5.0
  • 5.5.1
  • 5.5.2
  • 5.6.0
  • 5.6.1
  • 5.6.2
  • 5.6.3
  • 5.7.0
  • 5.7.1
  • 5.7.2
  • 5.8.0
  • 5.8.1
  • 5.8.2
  • 5.9.0
  • 5.9.1
  • 5.9.2
  • 5.9.3
  • 5.10.0
  • 5.10.1
  • 5.10.2
  • 5.10.3
  • 5.10.4
  • 5.10.5
  • 5.11.0
  • 5.11.1
  • 5.11.2
  • 5.11.3
  • 5.11.4
  • 5.12.0
  • 5.12.1
  • 5.12.2
  • 5.13.0
  • 5.13.1
  • 5.13.2
  • 5.13.3
  • 5.13.4
  • 5.14.0
  • 5.14.1
  • 6.0.0
  • 6.0.1

  Versions in green have been tested.

• JDK 25
• Maven 3.9.11