When diving into the world of testing microservices in Java, especially when working with JUnit, Spring Boot, and MockMvc, things can seem a bit daunting. But fear not! The journey involves getting acquainted with a handful of essential concepts and tools. These tools will empower you to set up and execute comprehensive tests that will ensure your microservices work like a charm.

To kick things off, having a polished development environment is step one. Typically, developers lean on an Integrated Development Environment (IDE) such as Visual Studio Code or IntelliJ IDEA, customized with the right extensions for Java. Apache Maven often stars in the background, managing dependencies and driving project builds.

Then, there’s JUnit—a name that rings familiar in the ears of Java aficionados. This testing framework is the go-to for writing unit tests, integration tests, and the like. For microservices, JUnit 5—or Jupiter as it’s affectionately known—is the favorite pick, partly due to its excellent support for parameterized tests and new features.

When Spring Boot enters the picture, it brings simplicity to the chaotic world of developing microservices. Spring Boot handles much of the configuration, leaving developers with the mental bandwidth to focus on building functionality. And to this slick setup, add MockMvc—a tool that turns the testing of HTTP requests into a breeze without needing to fire up a web server.

Unit tests, the unsung heroes of a solid test strategy, are about focusing on individual pieces of code, ensuring that each behaves exactly as it should. Quick to write and verify, unit tests form the backbone of a healthy testing culture within teams dealing with microservice architecture.

Imagine trying to dig deeper, testing how different parts of your microservice dance together. That’s where integration tests come in. And MockMvc shines in this domain, allowing developers to test Spring MVC controllers seamlessly sans the need to start the whole application.

Stepping into mocking and stubbing means replicating behavior of external dependencies to isolate and focus on the unit at hand. This where Mockito steals the spotlight, a favored library for creating mocks in the Java universe. It’s essentially a scene where one can stage elaborate playacting of service behaviors to perfect your service responses.

Every now and then the horizon demands parameterized testing. This allows testing the same code with varied input data. Imagine a scenario dealing with REST endpoints with multiple parameters—parameterized tests come to the rescue, facilitating the running of tests with different input combinations.

Thriving in development also means running tests in development mode which involves setting up local servers mimicking production environments. For example, if you’re into Open Liberty, you might find yourself configuring tests to run in a local setup simulating production settings.

In the toolkit arsenal, several frameworks and tools such as JUnit for testing, MockMvc for Spring MVC specifics, Mockito for mocking, RestAssured for API testing, and WireMock for external service simulation make life easier. Utilizing TestContainers for testing real dependencies is another helpful practice, bringing real-world testing scenarios closer to home.

Walking hand-in-hand with best practices can immensely boost microservice testing. Perhaps you’ve heard whispers about the Test Pyramid—it advises that unit tests should dominate your suite, with integration and end-to-end tests rounding out the lineup. Mocking external dependencies keeps tests isolated and easier to manage while parameterized tests help blanket a wider array of scenarios. Seamlessly integrate tests into CI/CD pipelines ensuring tests become a part of every build process to avoid unwanted surprises down the road.

In retrospect, testing microservices requires juggling quite a few elements—from unit to integration and end-to-end tests. Yet, the robust troika of JUnit, Spring Boot, and MockMvc provides all one might need to ensure microservices stand tall, robust, and reliable. Lean on mocks and stubs to keep external dependencies at bay, indulge in parameterized tests to navigate diverse scenarios, and abide by best practices to keep everything shipshape. With such a strategy in play, the journey from code to deployment becomes a smoother, more confident ride.