Gain insights into JUnit 5, explore its advantages over JUnit 4, and delve into its features like assertions, parameterized tests, dependency injection, and test execution order. Discover hands-on projects to cement your skills.

junit.tar.gz

Parameter

Annotation

Slow

file

json

JUnit 5 is a standard framework for unit testing in Java. Released in 2017, JUnit 5 is a major improvement over JUnit 4 and supports a lot of new methods. Many projects have migrated from JUnit 4 to JUnit 5. JUnit 5 is also the default test framework for new projects. JUnit 5 is composed of three sub-projects: JUnit Platform, JUnit Jupiter, and JUnit Vintage. Details of these sub-projects are discussed in the course.

This course first discusses the advantages of JUnit 5 over the previous versions and then jumps directly into tests. The course includes discussion on assertions, assumptions, tagging and filtering, nested tests, dependency injection, repeated tests, parameterized tests, dynamic tests, test instance lifecycle, extension model, JUnit 4 migration, JUnit platform, and test execution order. 

By the end of this course, you’ll be deeply familiar with unit testing in JUnit 5. There’s also a little project for you at the end to put your newly acquired skills to the test.

All About JUnit5

Tags are added using the annotation `org.junit.jupiter.api.Tag`. The `@Tag` annotation is repeatable, so we can put multiple annotations in the same class or method. We can also use `org.junit.jupiter.api.Tags` to specify multiple tags. Tags are first trimmed by using `String.trim()`. A tag can’t be `null` or empty. A trimmed tag can’t contain whitespace or ISO control characters. For example, `@Tag("hello world")` is invalid.

>**Note:** We can still add trimmed tags with whitespaces to our test classes or methods. The code compiles successfully, but those tags are ignored by JUnit5. JUnit 5 issues warnings like the one below for these ignored tags.
>
>"**WARNING:** Configuration error: invalid tag syntax in @Tag(“hello world”) declaration on [public void io.educative.junit5.tagTest.manyTags()]. Tag will be ignored."

The `@Tag` annotation can also be used as a meta-annotation. This is useful when creating type-safe tags to avoid mistakes caused by typos. The code below shows a custom annotation, `@Slow`, that represents the tag `slow`. The `@Slow` annotation is essentially the same as `@Tag("slow")`, but it’s type-safe. We don’t need to worry about typos like `@Tag("slaw")`. They may require too much time to debug in order to determine why a test isn’t included.
# Using `@Tag`
We’ve used the annotation libraries in the code below:
- The `ElementType` library provides a classification of declared elements.
- The `Retention` library indicates the retention length of annotations with the annotated type.
- The `RetentionPolicy` library is the default retention policy if we don’t specify one.
- The `Target` library annotation declares possible join points that can be decorated by that annotation.

Learn how to add tags to test classes and methods and how to use filters in JUnit 5.

Getting Started

Writing Basic Tests

Annotations, Tagging, and Filtering

Nested tests in JUnit 5

Dependency Injections

Parameterized and Dynamic Tests

Test Instance Lifecycle in JUnit 5

Extension Model

JUnit Platform

Test Execution Order

Conclusion

Library Management System

Tags and Filtering

Testing with `@Tag`

Library Management System

Tags and Filtering

Testing with @Tag

Testing with `@Tag`