0Pricing
Groovy & Gradle: JVM Automation and Build Engineering · Lesson

Test Fixtures and Shared Test Code

Use the java-test-fixtures plugin to share reusable test helpers, builders, and fakes across modules without leaking them into production code.

Test Fixtures and Shared Test Code is a free Groovy & Gradle: JVM Automation and Build Engineering lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Groovy & Gradle: JVM Automation and Build Engineering learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

The Shared Test Code Problem

Multiple modules often need the same test helpers (builders, fakes, fixtures). Copy-pasting them is brittle, and putting them in main code ships test-only classes to production.

Enter Test Fixtures

Gradle ships the java-test-fixtures plugin, which adds a dedicated testFixtures source set whose code can be consumed by other modules tests.

plugins {
    id("java-library")
    id("java-test-fixtures")
}

Source Set Layout

The plugin creates src/testFixtures/java. Classes there are compiled separately and packaged into a fixtures artifact.

  • src/main production
  • src/test tests
  • src/testFixtures shared test helpers

Writing a Fixture

Place reusable builders in the fixtures source set. They can depend on the main classes of the module.

public class UserBuilder {
    public static User aUser() {
        return new User("test", 42);
    }
}

Using Fixtures Inside the Module

The modules own tests automatically see its fixtures, no extra configuration needed.

@Test
void usesFixture() {
    User u = UserBuilder.aUser();
    assertEquals(42, u.getId());
}

Consuming Fixtures Across Modules

Another module declares a dependency on the fixtures using the testFixtures() helper.

dependencies {
    testImplementation(testFixtures(project(":core")))
}

Fixture Dependencies

Fixtures can declare their own dependencies with the testFixturesImplementation configuration, kept separate from production deps.

dependencies {
    testFixturesImplementation("org.assertj:assertj-core:3.25.0")
}

Why Not Just Use main?

Putting test helpers in main leaks them into the published JAR and the production classpath, increasing size and risk. Fixtures keep them isolated.

Publishing Fixtures

The fixtures artifact can be published alongside the main JAR, so downstream consumers in other repositories reuse them too.

gradle publish

Comparison with a Separate Module

You could create a standalone test-helpers module, but fixtures avoid an extra module, keep helpers next to the code they support, and use a clear naming convention.

Best Practices

Keep fixtures focused:

  • Only put genuinely reusable helpers here
  • Avoid leaking fixtures into main accidentally
  • Name builders/fakes clearly

Quick Check

Test your understanding of test fixtures.

Recap

You learned test fixtures:

  • Apply java-test-fixtures
  • Put shared helpers in src/testFixtures
  • Consume with testFixtures(project(...))
  • Keeps test-only code out of production artifacts

Frequently asked questions

Is the “Test Fixtures and Shared Test Code” lesson free?

Yes — the full text of “Test Fixtures and Shared Test Code” is free to read here on the web, and the Groovy & Gradle: JVM Automation and Build Engineering course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Groovy & Gradle: JVM Automation and Build Engineering course, upgrade to CoddyKit PRO.

What will I learn in “Test Fixtures and Shared Test Code”?

Use the java-test-fixtures plugin to share reusable test helpers, builders, and fakes across modules without leaking them into production code. You practise Groovy & Gradle: JVM Automation and Build Engineering with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Groovy & Gradle: JVM Automation and Build Engineering?

No prior experience is required. Groovy & Gradle: JVM Automation and Build Engineering on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “Test Fixtures and Shared Test Code” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Groovy & Gradle: JVM Automation and Build Engineering lesson?

Yes. Every Groovy & Gradle: JVM Automation and Build Engineering lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. Unit & Integration Testing
  2. Test Reports & Filtering
  3. Code Coverage & Static Analysis
  4. Test Fixtures and Shared Test Code
← Back to Groovy & Gradle: JVM Automation and Build Engineering