Gradle TestKit Support Plugin

A plugin to simplify usage of Gradle TestKit. It has two features of primary interest to seasoned Gradle TestKit users:

1. It lets you completely avoid usage of GradleRunner.withPluginClasspath(), which is broken. Instead, it installs your plugin and all of its local project dependencies into a local file repo at $rootDir/build/functionalTestRepo/. It provides a reference to this location into your functional test JVM via the system property "com.autonomousapps.plugin-under-test.repo". This repo is also available to your test suite via Repository.FUNC_TEST, which brings us to…​

2. Support for generating test fixtures via GradleProject and AbstractGradleProject, semantically instead of using raw strings. See the sample code below. A very thorough set of examples is available in the Dependency Analysis Gradle Plugin test suite under src/functionalTest/groovy in the root build of this repo.

Add to your project

The plugin comes with two optional dependencies to further improve the experience of writing functional tests for your Gradle plugins, gradle-testkit-support and gradle-testkit-truth. The former provides additional help in writing test fixtures, while the latter is useful if you already use Google Truth for writing test assertions.

Every project in your plugin’s build must apply this plugin for it to work.

my-plugin/build.gradle

plugins {
  id 'java-gradle-plugin'
  id 'com.autonomousapps.testkit' version '<<latest>>'
}

group = 'com.company'
version = '1.0'

// Optional but encouraged
dependencies {
  functionalTestImplementation('com.autonomousapps:gradle-testkit-support:<<latest>>')
  functionalTestImplementation('com.autonomousapps:gradle-testkit-truth:<<latest>>')
}

// Alternative to the above
gradleTestKitSupport {
  withSupportLibrary(/* optional version*/)
  withTruthLibrary(/* optional version*/)
}

other-project/build.gradle

plugins {
  id 'com.autonomousapps.testkit' version '<<latest>>'
}

group = 'com.company'
version = '1.0'

Usage

$ ./gradlew :my-plugin:functionalTest

Sample test code

src/functionalTest/kotlin/com/company/Test.kt

package com.company

import com.autonomousapps.kit.AbstractGradleProject
import com.autonomousapps.kit.GradleBuilder.build
import com.autonomousapps.kit.GradleProject
import com.autonomousapps.kit.Source
import com.autonomousapps.kit.SourceType
import com.autonomousapps.kit.gradle.Dependency.implementation
import com.autonomousapps.kit.gradle.Plugin
import com.autonomousapps.kit.truth.TestKitTruth.assertThat
import org.junit.jupiter.api.Test

class Test {
  @Test fun test() {
    // Given
    val project = MyFixture().build()

    // When
    val result = build(project.rootDir, ":project:myTask")

    // Then
    assertThat(result).task(":project:myTask").succeeded()
  }
}

class MyFixture : AbstractGradleProject() {

  // Injected into functionalTest JVM by the plugin
  // Also available via AbstractGradleProject.PLUGIN_UNDER_TEST_VERSION
  private val pluginVersion = System.getProperty("com.autonomousapps.plugin-under-test.version")

  fun build(): GradleProject {
    return newGradleProjectBuilder()
      .withSubproject("project") {
        sources = projectSources
        withBuildScript {
          plugins(Plugin.javaLibrary, Plugin("my-cool-plugin", pluginVersion))
          dependencies(implementation("com.company:library:1.0"))
        }
      }
      .write()
  }

  private val projectSources = mutableListOf(
    Source.java(
      """
      package com.example.project;

      public class Project {
        // do stuff here
      }
      """
    )
      .withPath(/* packagePath = */ "com.example.project", /* className = */ "Project")
      .build()
  )
}