Testing Spring Boot Applications with JUnit 5 and Mockito

Writing automated tests is a fundamental skill for any professional Java developer. Delivering robust, bug-free Spring Boot applications requires a solid understanding of how to isolate components, mock dependencies, and verify system behavior. This text-based course guides you through the core concepts of software testing, taking you from writing your first JUnit test to configuring complex integration tests. You will learn how to apply Test-Driven Development (TDD) principles, isolate code with Mockito, and utilize Spring Boot's powerful testing utilities to ensure your applications run flawlessly. What you'll learn: - Understand the core concepts of unit testing, integration testing, and the testing pyramid in Java. - Write clean, expressive assertions using JUnit 5 and modern assertion libraries like AssertJ. - Isolate classes under test by mocking external dependencies and defining behaviors with Mockito. - Test Spring Boot web layers and REST controllers using MockMvc without spinning up a full server. - Configure integration tests with real databases using lightweight containerized environments like Testcontainers. - Apply Test-Driven Development (TDD) workflows to design higher-quality code from the ground up. The course begins with foundational testing definitions and basic JUnit 5 lifecycle methods before moving into mock objects, Spring context testing, and advanced integration scenarios. You will progress naturally through written explanations and practical code snippets from simple unit tests to comprehensive slice and integration test suites. This course is designed for beginner to intermediate Java developers who want to learn professional testing practices from scratch. Basic knowledge of Java and Spring Boot is recommended, but no prior testing experience is required. Start writing reliable, maintainable code and elevate your development workflow today.