Unit Testing Java Programs Using JUnit5 and Mockito

What are Unit Tests?

In Unit Tests, we test the a unit - the smallest piece of logical code, in a program. Generally this unit is an individual method of a class. 

Junit Framework?

JUnit framework allows us to write and run unit tests. As per official JUnit documentation,

JUnit is a simple framework to write repeatable tests. It is an instance of the xUnit architecture for unit testing frameworks.

Mockito Framework?

Mockito is an open source testing framework for Java released under the MIT License. Mockito helps us to create dummy implementation for an interface or a class. In a dummy implementation we can define behaviour of a method to support our test requirements. Mockito works in conjunction with JUnit and allows us to create repeatable automated tests.

Tutorials.

• A very simple JUnit5 test
• Mocking dependencies without using Mockito
  
• Mocking external dependencies for Unit Testing using Mockito
  
• Various ways to mock a dependency using Mockito
• Verify method or mock object invocation
  
• Specify return value from a mocked method
• Verify arguments passed to any mocked method
• Mock void methods
• How to verify values passed to a mocked method?
• Test Callback Invocation using Junit5 and Mockito
• Junit5 Parametrized Tests