Gain insights into unit testing with JUnit 5. Learn about assertions, assumptions, nested and parameterized tests, advanced JUnit 5 concepts, and integrating tests with Maven and Gradle.

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junit5.tar.gz

mvn clean test

Unit Testing is a basic and essential skill to learn for any developer. In this course, you will learn what unit tests are, why they are important, and how to test your Java applications using the JUnit 5 Framework —  the most popular unit testing framework in the market for Java developers.

You will start with the fundamentals of Unit Testing and JUnit 5 and then gradually you will dive deep into the core concepts like assertions, assumptions, different types of tests like nested tests, parameterized tests, repeated tests, and more.

You will also learn some advanced concepts of JUnit 5 like the JUnit 5 extension model, dependency injection, how to migrate existing unit tests from JUnit 4 to JUnit 5, and how to integrate your unit tests with Maven and Gradle.

Unit Testing Java Applications using JUnit 5

Each JUnit5 test follows a life cycle where it goes through different phases.

The following are the three phases involved as parts of the test life cycle:


- Setup
- Execution
- Cleanup



- **Setup**: The test infrastructure and the required configuration is prepared. This setup is prepared at two levels.
  * The first one is at the class level where we can setup/configure a resource like a Database Connection and insert required Test Data into the database. This phase runs *only once* per Test class.
  * The second one is at the test level, where we initialize the required objects for the test execution. This allows us to remove duplicated code inside the tests. This phase runs before every test method.

- **Execution**: The tests are executed and verified. We mark the test as a success or a failure based on this.
- **Cleanup**:  We have the below two levels of cleanup:
  * Test-level cleanup is where we perform some cleanup activities after *every* test method is executed.
   * Class-level cleanup is where we cleanup or release the resources that are configured as a part of the class level setup phase. This phase runs *only once* per test class.

# Test life cycle annotations in JUnit 5

JUnit 5 provides the following set of annotations for each phase of the test life cycle:

- `@BeforeAll` (Class-level setup)
- `@BeforeEach` (Test-level setup)
- `@Aftereach` (Test level cleanup)
- `@AfterAll` (Class level cleanup)

Understand the life cycle of a unit test in JUnit 5.

Before We Begin

Introduction to JUnit 5

Junit 5 Core Concepts

Dynamic Tests

Dependency Injection in JUnit 5

JUnit 5 Extensions

Migrating from Junit 4 to Junit 5

Appendix

BONUS: Useful Assertion Libraries

Conclusion

Understanding JUnit 5 Life Cycle