If you find yourself copying and pasting code from your application's build.gradle file every time you start a new project, then it's time you learn about creating Gradle plugins. In this presentation you will learn about what it takes to create a custom Gradle plugin for use in your Android applications. It covers: Plugin Structure, Key Components, Testing, and Publishing

1. Creating Gradle Plugins
Annyce Davis - @brwngrldev

2. @brwngrldev
Without Plugins

3. @brwngrldev
With Plugins

4. Overview
• Plugin Skeleton
• Dependencies
• Plugin.groovy
• CustomTask.groovy
• Publishing
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5. Plugin Skeleton
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6. Plugin Skeleton

7. Plugin Skeleton
How Gradle finds the Plugin Implementation

8. Dependencies
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apply plugin: ‘groovy'
dependencies {
compile gradleApi()
compile localGroovy()
}

9. Plugin.groovy
Implement the Plugin interface and override apply method
class CustomPlugin implements Plugin<Project> {
@Override
void apply(Project project) {
}
}

10. QualityChecksPlugin.groovy
Implement the Plugin interface and override apply method

11. Apply Method
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Creates the tasks for the plugin and performs any setup

12. Project Extension
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Allows the user to customize the behavior of the plugin

13. Project Extension
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Back in the application’s build.gradle file…

14. Creating tasks
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Give it a name and a type

15. @brwngrldev

16. CustomTask.groovy
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class CustomTask extends DefaultTask {
}

17. CustomTask.groovy
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class CustomTask extends DefaultTask {
@TaskAction
def defaultAction() {
}
}

18. CustomTask.groovy
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class CustomTask extends DefaultTask {
@TaskAction
def defaultAction() {
< do your cool stuff >
}
}

19. So far…
• Plugin Skeleton
• Dependencies
• Plugin.groovy
• CustomTask.groovy
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20. Questions?

21. Publishing
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22. Publishing
buildscript {
repositories {
maven {
url "https://plugins.gradle.org/m2/"
}
}
dependencies {
classpath "com.gradle.publish:plugin-publish-plugin:0.9.2"
}
}
apply plugin: 'com.gradle.plugin-publish'

23. version = "0.1.3"
group = "info.adavis"

24. version = "0.1.3"
group = "info.adavis"
pluginBundle {
website = 'https://github.com/adavis/quality-checks'
vcsUrl = 'https://github.com/adavis/quality-checks.git'
description = 'Gradle Plugin for…’
tags = ['Checkstyle', 'FindBugs', 'PMD']
}

25. version = "0.1.3"
group = "info.adavis"
pluginBundle {
website = 'https://github.com/adavis/quality-checks'
vcsUrl = 'https://github.com/adavis/quality-checks.git'
description = 'Gradle Plugin for…’
tags = ['Checkstyle', 'FindBugs', 'PMD']
plugins {
qualityChecksPlugin {
id = 'info.adavis.qualitychecks'
displayName = 'Quality Checks Plugin'
}
}
}

26. Publishing
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Once your Plugin is published on the Gradle portal

27. We’re done…
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WRONG!

28. We’re done…
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TESTS

29. Testing
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You can use JUnit and the ProjectBuilder for most testing

30. Testing
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@Test
void shouldBeAbleToCreateTask() {
assertTrue(task instanceof WriteConfigFileTask)
}

31. Testing
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@Test
void shouldBeAbleToCreateTask() {
assertTrue(task instanceof WriteConfigFileTask)
}
@Test
void pluginShouldBeApplied() {
def project = ProjectBuilder.builder().build()
project.apply(plugin: QualityChecksPlugin)
assertNotNull(project.tasks.findByName(‘mytask’))
}

32. Bonus: README
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33. Bonus: README
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34. Summary
• Helps avoid copy/paste horror
• Simple project structure
• Extending DefaultTask
• Testing techniques
• Easy to publish
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35. Next Steps
✓Sample: https://git.io/vzJ2w
✓Sample: https://git.io/vzJwS
✓Applaud 😉
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36. Thanks!
@brwngrldev
+AnnyceDavis
www.adavis.info
@brwngrldev