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.

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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

## What's dependency injection?
It’s common for a test method to use external dependencies. In JUnit 5, test constructors and methods can have parameters to inject dependencies. However, not all types of parameters are allowed in constructors or methods. Extensions should be defined to resolve the parameters. The extension model allows for registering custom parameter resolvers. In this category, we only cover the built-in parameter resolvers. The `org.junit.jupiter.api.extension.ParameterResolver` is the interface for parameter resolvers.

JUnit 5 has three built-in parameter resolvers:

* `TestInfoParameterResolver`
* `TestReporterParameterResolver`
* `RepetitionInfoParameterResolver`



# What's dependency injection?
It’s common for a test method to use external dependencies. In JUnit 5, test constructors and methods can have parameters to inject dependencies. However, not all types of parameters are allowed in constructors or methods. Extensions should be defined to resolve the parameters. The extension model allows for registering custom parameter resolvers. In this category, we only cover the built-in parameter resolvers. The `org.junit.jupiter.api.extension.ParameterResolver` is the interface for parameter resolvers.

JUnit 5 has three built-in parameter resolvers:

* `TestInfoParameterResolver`
* `TestReporterParameterResolver`
* `RepetitionInfoParameterResolver`



Understand how to use dependency injection (TestInfo parameter) in Constructor and Test methods.

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

Parameter Resolver: TestInfo

What’s dependency injection?