LaunchWrapperTestSuite

LaunchWrapperTestSuite makes it possible to run JUnit tests that require transformed classes. It provides a custom test runner that will load the test class in a separate LaunchClassLoader that applies previously configured transformers.

Setup

LaunchWrapperTestSuite can be used with any build system. The following examples will use Gradle.

1. Add test dependency on LaunchWrapperTestSuite:

   dependencies {
       testCompile 'org.spongepowered:lwts:1.0.0'
   }

2. Implement a test tweak class that configures the transformers. LaunchWrapperTestSuite comes with AbstractTestTweaker which provides some utility methods and sets up the class loader to work with JUnit.

   package com.example.test.launch;
   
   import net.minecraft.launchwrapper.LaunchClassLoader;
   import org.spongepowered.lwts.AbstractTestTweaker;
   
   public class MyTestTweaker extends AbstractTestTweaker {
   
       @Override
       public void injectIntoClassLoader(LaunchClassLoader loader) {
           // Important so we can configure some settings for JUnit
           super.injectIntoClassLoader(loader);
           
           // Configure your transformers here (a few examples below)
           
           // Access transformer
           registerAccessTransformer("META-INF/test_at.cfg");
           
           // Mixin environment
           MixinBootstrap.init();
           Mixins.addConfiguration("mixins.test.json");
           // Set Mixin side, otherwise you get a warning when running the tests
           MixinEnvironment.getDefaultEnvironment().setSide(SERVER);
           
           // Custom transformer
           loader.registerTransformer("com.example.test.launch.transformer.MyCustomTransformer");
       }
   
   }

3. Set a system property lwts.tweaker with the full qualified class name of your tweaker:

   test {
       systemProperty 'lwts.tweaker', 'com.example.test.launch.MyTestTweaker'
       
       // Run tests in a temporary directory
       workingDir = {test.temporaryDir}
   }

Usage

To make a test class use the custom test runner, all you need to do is add a annotation to it:

@RunWith(LaunchWrapperTestRunner.class)
public class MyTest {

    @Test
    public void testSomething() {
        // ...
    }

}

When you run your tests using gradle test it should load the test class in the custom classloader and apply the configured transformers.

Parameterized test

If you are using a parameterized test you need to change the test runner to LaunchWrapperParameterized:

@RunWith(LaunchWrapperParameterized.class)
public class MyParameterizedTest {

    @Parameterized.Parameters
    public static Collection<Object[]> getParameters() {
        // ...
    }

}