JUnit 5 is the next generation of JUnit. The goal is to create an up-to-date foundation for developer-side testing on the JVM. This includes focusing on Java 8 and above, as well as enabling many different styles of testing.

Unlike previous versions of JUnit, JUnit 5 is composed of several different modules from three different sub-projects.

JUnit 5 = JUnit Platform + JUnit Jupiter + JUnit Vintage

JUnit Platform serves as a foundation for launching testing frameworks on the JVM.
JUnit Jupiter is the combination of the new programming model and extension model for writing tests and extensions in JUnit 5. The Jupiter sub-project provides a TestEngine for running Jupiter based tests on the platform.
JUnit Vintage provides a TestEngine for running JUnit 3 and JUnit 4 based tests on the platform.

Implementation

testImplementation 'org.junit.jupiter:junit-jupiter-api:5.7.2'

testImplementation(platform('org.junit:junit-bom:5.7.2'))
testImplementation('org.junit.jupiter:junit-jupiter')

Some useful info

Ctrl + Shift + T - for create new test for current class

Annotations

@Test

Denotes that a method is a test method Методы для выполнения тестов, будут вызваны при запуске теста

@BeforeEach

Denotes that the annotated method should be executed before each @Test, @RepeatedTest, @ParameterizedTest, or @TestFactory method in the current class

@AfterEach

Denotes that the annotated method should be executed after each @Test, @RepeatedTest, @ParameterizedTest, or @TestFactory method in the current class

@BeforeAll

Denotes that the annotated method should be executed before all @Test, @RepeatedTest, @ParameterizedTest, and @TestFactory methods in the current class

@AfterAll

Denotes that the annotated method should be executed after all @Test, @RepeatedTest, @ParameterizedTest, and @TestFactory methods in the current class

@DisplayName

Declares a custom display name for the test class or test method.

Отображаемое название теста
Значение аннотации имеет приоритет перед названием функции
Аннотация применима и к классу

@DisplayName("Override class name")
class HelloJunit5Test {

    @DisplayName("\uD83D\uDC4D")
    @Test
    fun `First test ╯°□°）╯`() {
        print("Hello, JUnit5!")
    }
}

@Disabled

Used to disable a test class or test method; analogous to JUnit 4’s @Ignore. Such annotations are not inherited.

@Disabled("Disabled until bug #2019 has been fixed!")
public class DisabledClassTest {

    @Disabled("Disabled until CustomerService is up!")
    @Test
    void testCustomerServiceGet() {
        assertEquals(2, 1 + 1);
    }

}

@RepeatedTest

Число повторений теста

@RepeatedTest(10, name = "{displayName} {currentRepetition} из {totalRepetitions}")
fun `Повторяемый тест`() {

}

Assertions

Assertion'ы находятся в классе org.junit.jupiter.Assertions и являются статическими методами.

Базовые assertion'ы

@Test
fun `Base assertions`() {
    assertEquals("a", "a")
    assertEquals(2, 1 + 1, "Optional message") // последним аргументом является сообщение, выводимое в случае ошибки
    assertEquals(2, 1 + 1, { "Assertion message " + "can be lazily evaluated" }) //лямбда-выражение вычисляется только в случае неудачного прохождения теста
    assertTrue(b)
    assertEquals(1.32, 2.05 - 0.73, 0.0001) // для дробных чисел позволяет указать дельту
    assertArrayEquals({1,2,3}, {1,2,3}) // Сравнивает массивы различных типов
    assertNull(null); // passed
    assertNotNull(null); // failed
    assertSame(obj, obj2); // use equals()
    assertNotSame(obj, obj2); // use equals()
    
    fail(); // Метод, который без всякой проверки просто завершит ваш тест неудачей
}

Групповые assertion'ы

class Person(val firstName: String, val lastName: String)

import org.junit.jupiter.api.Assertions.assertAll
import org.junit.jupiter.api.Assertions.assertEquals
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.function.Executable

class HelloJunit5Test {

    @Test
    fun `Grouped assertions`() {
        val person = Person("John", "Doe")
        assertAll("person",
                Executable { assertEquals("John", person.firstName) },
                Executable { assertEquals("Doe", person.lastName) }
        )
    }
}

Проверка времени выполнения тестов

@Test
fun `Timeout not exceeded`() {
    // Тест упадёт после выполнения лямбда-выражения, если оно превысит 1000 мс
    // Лямбда-выражение выполняется полностью, даже когда время выполнения уже превысило допустимое
    assertTimeout(ofMillis(1000)) {
        print("Выполняется операция, которая займёт не больше 1 секунды")
        Thread.sleep(3)
    }
}

@Test
fun `Timeout not exceeded with preemptively exit`() {
    // Тест упадёт, как только время выполнения превысит 1000 мс
    assertTimeoutPreemptively(ofMillis(1000)) {
        print("Выполняется операция, которая займёт не больше 1 секунды")
        Thread.sleep(3)
    }
}

Assumptions

Assumption'ы предоставляют возможность выполнения тестов только в случае выполнения определённых условий
Предположения позволяют указать условия, при которых должен выполняться тест-кейс. Если эти условия выполнения теста не соблюдаются, тест автоматически считается успешным.

Assumptions class provides following overloaded methods.

Assumptions.assumeTrue() – If the condition is true, then run the test, else aborting the test.
Assumptions.false() – If the condition is false, then run the test, else aborting the test.
Assumptions.assumingThat() – is much more flexible, If condition is true then executes, else do not abort test continue rest of code in test.

@Test
public void testEJB()
{
    assumeTrue(System.getProperty("java.version").startsWith("1.8"))
    // test something here
}

Extensions

The purpose of Junit 5 extensions is to extend the behavior of test classes or methods, and these can be reused for multiple tests.

JUnit 5 extensions are related to a certain event in the execution of a test, referred to as an extension point. When a certain life cycle phase is reached, the JUnit engine calls registered extensions.

Five main types of extension points can be used:

test instance post-processing
conditional test execution
life-cycle callbacks
parameter resolution
exception handling

TestInstancePostProcessor Extension

This type of extension is executed after an instance of a test has been created. The interface to implement is TestInstancePostProcessor which has a postProcessTestInstance() method to override.

Common use cases include injecting dependencies into the test instance, invoking custom initialization methods on the test instance, etc.

An extension that instantiates a logger object, then calls the setLogger() method on the test instance:

public class LoggingExtension implements TestInstancePostProcessor {

    @Override
    public void postProcessTestInstance(Object testInstance, 
      ExtensionContext context) throws Exception {
        Logger logger = LogManager.getLogger(testInstance.getClass());
        testInstance.getClass()
          .getMethod("setLogger", Logger.class)
          .invoke(testInstance, logger);
    }
}

Conditional Test Execution

JUnit 5 provides a type of extension that can control whether or not a test should be run. This is defined by implementing the ExecutionCondition interface.

The method verifies if a property representing the current environment name equals “qa” and disables the test in this case:

public class EnvironmentExtension implements ExecutionCondition {

    @Override
    public ConditionEvaluationResult evaluateExecutionCondition(
      ExtensionContext context) {
        
        Properties props = new Properties();
        props.load(EnvironmentExtension.class
          .getResourceAsStream("application.properties"));
        String env = props.getProperty("env");
        if ("qa".equalsIgnoreCase(env)) {
            return ConditionEvaluationResult
              .disabled("Test disabled on QA environment");
        }
        
        return ConditionEvaluationResult.enabled(
          "Test enabled on QA environment");
    }
}

Lifecycle Callbacks

This set of extensions is related to events in a test's lifecycle and can be defined by implementing the following interfaces:

BeforeAllCallback and AfterAllCallback – executed before and after all the test methods are executed
BeforeEachCallBack and AfterEachCallback – executed before and after each test method
BeforeTestExecutionCallback and AfterTestExecutionCallback – executed immediately before and immediately after a test method

If the test also defines its lifecycle methods, the order of execution is:

BeforeAllCallback
BeforeAll
BeforeEachCallback
BeforeEach
BeforeTestExecutionCallback
Test
AfterTestExecutionCallback
AfterEach
AfterEachCallback
AfterAll
AfterAllCallback

A Guide to JUnit 5 Extensions

JUnit 5 User Guide
Тестирование с помощью JUnit 5 на Kotlin
10 интересных нововведений в JUnit 5

JUnit 5 - makstron/info GitHub Wiki

Implementation

Some useful info

Annotations

@Test

@BeforeEach

@AfterEach

@BeforeAll

@AfterAll

@DisplayName

@Disabled

@RepeatedTest

Assertions

Базовые assertion'ы

Групповые assertion'ы

Проверка времени выполнения тестов

Assumptions

Extensions

TestInstancePostProcessor Extension

Conditional Test Execution

Lifecycle Callbacks

⚠️ GitHub.com Fallback ⚠️

JUnit 5 - makstron/info GitHub Wiki

Implementation

Some useful info

Annotations

@Test

@BeforeEach

@AfterEach

@BeforeAll

@AfterAll

@DisplayName

@Disabled

@RepeatedTest

Assertions

Базовые assertion'ы

Групповые assertion'ы

Проверка времени выполнения тестов

Assumptions

Extensions

TestInstancePostProcessor Extension

Conditional Test Execution

Lifecycle Callbacks

⚠️ **GitHub.com Fallback** ⚠️

⚠️ GitHub.com Fallback ⚠️