Start by exploring automated software testing and the typical pitfalls it helps avoid. Then, gain hands-on experience with Java's JUnit 5 library and learn to structure and write unit tests.

Introduction to testing

Edge cases: NullPointerException

Importance of edge cases

Edge case: Digits of a number

Edge cases: Array maximum

Introduction to JUnit

Digits of a number

Digits of a number fail

Unit testing with JUnit

Currency conversion

Username validation

Handling Exceptions: Message Processing

Foundations of Testing

Examine how software components interact and rely on each other, and see how integration testing verifies these interactions by testing a class alongside its dependencies. This chapter then introduces mocking as a method to simulate dependencies and focus testing on the logic being evaluated.

Integration testing

Foreign exchange

What to assert on?

Foreign Exchange: Error scenario

Mocking and Stubbing in Unit Tests

Mocking invalid currencies - visual

Unit test: Foreign exchange market

Unit test: Foreign exchange exceptions

Verification in mocking

Unit test: Database message

Unit test: Database with a list

Unit test: Alerting

Testing with Dependencies

Explore multiple ways to make testing less verbose. One way to do so is parameterizing tests; another is using the @BeforeEach annotation. Finally, it presents a new way to think about testing.

Parameterized testing

Username Validation Parameterized

CsvSource: Digits

Additional annotations

Digits with MethodSource

ParameterizedTest: List sum

BeforeEach: Alerting

Test-driven development

Benefits of TDD

Applying TDD to reverse a number

Applying TDD to reverse a number - part two

Wrap-up

Further techniques and annotations

Testing is what sets professional software engineers apart; untested code is considered broken by default. In this course, you’ll learn how to improve the reliability of robust, resilient Java applications through testing. You’ll explore common testing types, practice using JUnit, the industry-standard Java testing framework, and simulate realistic testing scenarios with Mockito. You’ll also apply Test-Driven Development and learn to write parameterized and integration tests. By the end, you'll be equipped to ensure your Java code is thoroughly and meaningfully tested.

<h2>Why Testing Matters</h2> Testing is one of the most important skills that separates beginners from professional software engineers. In the real world, especially in enterprise environments, any code that is not tested is assumed to be broken. Testing is not an optional step - it is a fundamental responsibility of software engineers and a key part of maintaining robust and resilient Java applications. Java is widely known for its stability and reliability, and testing plays a major role in upholding these qualities. <br> <h2>What You Will Learn</h2> This course will guide you through the core concepts of software testing in Java. You will start by learning about the most common types of tests and how they are used to improve code quality and application behavior. You will gain hands-on experience with JUnit, the most widely used testing framework in the Java ecosystem, and learn how to simulate complex testing scenarios using Mockito. As you progress, you will apply the methodology of Test Driven Development and learn to write both parameterized and integration tests. By the end of the course, you will have the tools and techniques you need to confidently write meaningful tests that ensure your code is reliable, maintainable, and production-ready.

Input/Output and Streams in Java

Learn how to write effective tests in Java using JUnit and Mockito to build robust, reliable applications with confidence.

Introduction to Testing in Java

What to assert on?

Introduction to Testing in Java

Hands-on interactive exercise