This page describes how we can write our first test class with JUnit 5. After we have finished this blog postpage, we:

• Can create test classes with JUnit 5.
• Know how we can use setup and teardown methods.
• Understand how we can write simple test methods with JUnit 5.

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Setup  Setup and Teardown methods

A test class can have four setup and teardown methods that must fulfill these two conditions:

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• The method that is annotated with the @BeforeAll annotation must be static, and it's run once before any test method is run.
• The method that is annotated with the @BeforeEach is invoked before each test method.
• The method that is annotated with the @AfterEach annotation is invoked after each test method.
• The method that is annotated with the @AfterAll annotation must be static, and it's run once after all test methods have been run.

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The firstTest() method and secondTest() method have a custom display name and they write a unique string to System.out.

import org.junit.jupiter.api.*;
 
@DisplayName("JUnit 5 Overview Exampleclass")
class JUnit5ExampleTestJUnit5OverviewTest {

//    Setup
    @BeforeAll
    static void beforeAll() {
        System.out.println("Before\nBefore all test methods \n");
//        Some examples of common expensive operations are:
//       - the creation of a database connection
//       - the startup of a server.
    }
 
    @BeforeEach
    void beforeEach() {
        System.out.println("  Before each test method");
//        This is useful when we want to execute some common code before running a test.
//        - list initialization
    }

//    Teardown
    @AfterEach
    void afterEach() {
        System.out.println("  After each test method \n");
    }
 
    @AfterAll
    static void afterAll() {
        System.out.println("After all test methods\n");
    }
 
// Added test methods

    @Test
    @DisplayName("First test")
    @Test
    void firstTest() {
        System.out.println("    First test method");
    }
 
    @Test
    @DisplayName("Second test")
    void secondTest() {
        System.out.println("    Second test method");
    }


}

We have just written our first test methods. Let's see what happens when we run our unit tests.

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This tutorial has taught us four three things:

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• Setup and teardown methods must not be private and they must not return anything.
• A test method is a method that isn't private and doesn't return anything.
• We could specify the display name of a test class and a test method because this allows us to replace technical names with sentences that make sense.