Mastering JUnit: Techniques from Victor Rentea's Toolbox 🧰

Are you ready to test like a pro, or just tired of flaky tests? At Victor Rentea's recent meetup, we delved into the world of JUnit, where testing isn’t just a chore—it’s an art. From intercepting test execution to ditching assertEquals for something better, here’s the breakdown with a dash of humor and visuals to keep you awake.

1. Avoid the Waste: Feature Files Nobody Reads 🗑️

(I don't believe in this)

If there’s one thing Victor warned us about, it’s WASTE. Imagine toiling over .feature files that no businessperson ever approves. That's like building a ship for people who never plan to sail! Don’t maintain something that doesn’t have value; your tests should be assets, not liabilities. ⚖️

Pro Tip: Before you dive into feature files, ask yourself: "Will the business actually care?" If not, simplify or refocus those test cases.

Personal Thoughts 💭: I believe feature files should be written by developers, not even QAs or business people. Even if a businessperson isn't interested, these files are still valuable for maintaining quality and ensuring the code is readable by humans.

2. Say Goodbye to assertEquals 👋

assertEquals? We don’t know her. In Victor’s world, assertEquals is yesterday’s news. Why? Because AssertJ and Hamcrest give us way more readable, fluent assertions. Here’s a taste:

// Using AssertJ for clarity
assertThat(myList).contains("Apple").doesNotContain("Orange");

See the difference? AssertJ makes it more obvious what’s expected, giving you readable and maintainable tests. 📜

3. Parameterized Tests: Go Orthogonal or Go Home 🏠

When it comes to parameterized tests, low multicollinearity is key. What does that mean? Think of it like the spice mix in your favorite dish—too many overlapping flavors, and you end up with a mess. So, keep your test parameters orthogonal (fancy word for "non-overlapping") to avoid redundancy and ensure you’re truly testing unique combinations. 🍲

Best Practice: Avoid overlapping parameters that can muddy up your results and make test failures harder to diagnose.

4. From Flaky to Rock-Solid: @RepeatedTest 🛠️

We’ve all been there—tests that pass locally but fail in CI, or as we lovingly call them, "flaky tests." Enter @RepeatedTest, the annotation for the ultimate stress test. This lets you repeat a test several times to catch those pesky edge cases that only show up on the third or fourth run.

@RepeatedTest(10)
void shouldPassAllTheTime() {
    // Flaky code fixed with multiple runs
}

This isn’t just a “try until you pass” game; it’s about consistency and rooting out hidden bugs. 🐞

5. Profiling Tests and OutputCapture 🔍

Imagine running your tests with no clue what’s going on behind the scenes. OutputCapture to the rescue! Use this to capture and analyze your output, giving you insights into what your tests are actually doing. Profiling tests is like a health check-up for your code—you get to see what’s slowing you down and optimize as needed. 🩺

Essential Tools You’ll Need 🧰

Victor recommended a range of tools to supercharge your JUnit testing:

• WireMock 🕹️: A tool for mocking out external services and dependencies. With WireMock, you can simulate HTTP responses, allowing you to test your application’s behavior without needing access to the real service. This is especially useful in microservices architecture, where services may depend on external APIs that are difficult to control in test environments.

• @SpringBootTest & @ActiveProfiles 🏗️: These annotations in Spring Boot make it easier to control test environments. @SpringBootTest sets up a Spring application context for integration testing, while @ActiveProfiles allows you to specify which profiles should be active during the test. This way, you can isolate configurations and environments for testing, development, and production.

• @cucumber & @ContextConfiguration 🥒: For behavior-driven development (BDD) with Cucumber, @cucumber helps integrate your tests with a Cucumber framework. @ContextConfiguration is used to specify application contexts in Spring Boot, allowing for smooth integration with Cucumber for writing and executing feature files that reflect real-world scenarios.

These tools streamline your testing process, making it possible to test complex scenarios with a consistent setup, saving you from manual setup and tear-down for every test run.

Books & Resources for Further Mastery 📚

If you’re hungry for more, here’s Victor’s recommended reading and watching list:

• Books:
  • Art of Unit Testing by Roy Osherove
  • TDD by Example by Kent Beck
  • Growing Object-Oriented Software, Guided by Tests by Steve Freeman and Nat Pryce
• YouTube Talks:
  • Devoxx UK: Testing Like a Pro by Victor Rentea
  • Testing Microservices by Victor Rentea

Wrapping Up 🎉

JUnit isn’t just a testing framework; it’s a philosophy. Use custom annotations wisely, master parameterized tests, and remember, if no one’s reading those .feature files, maybe it’s time to hit delete. As Victor would say, testing is an art—one that requires mastery, dedication, and a good sense of humor. 😄

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