If you find yourself copying and pasting code from your build.gradle file every time you start a new project, then it's time you learn about Gradle Plugins. Come and learn what it takes to create a custom Gradle plugin for use in your Android/Java applications. We're going to go over the following: • Plugin Structure • Key Components • Testing • Publishing Walk away feeling empowered to create your own awesome plugins!

1. Gradle Plugin Goodness

2. @BRWNGRLDEV

3. @BRWNGRLDEV

4. apply plugin: 'checkstyle'
apply plugin: 'findbugs'
apply plugin: 'pmd'
task checkstyle(type: Checkstyle) {
description 'Checks if the code is somewhat acceptable'
group 'verification'
configFile file('./qa-check/checkstyle.xml')
source 'src'
include '**/*.java'
exclude '**/gen/**'
classpath = files()
ignoreFailures = false
}
task findbugs(type: FindBugs) {

5. apply plugin: 'checkstyle'
apply plugin: 'findbugs'
apply plugin: 'pmd'
task checkstyle(type: Checkstyle) {
description 'Checks if the code is somewhat acceptable'
group 'verification'
configFile file('./qa-check/checkstyle.xml')
source 'src'
include '**/*.java'
exclude '**/gen/**'
classpath = files()
ignoreFailures = false
}
task findbugs(type: FindBugs) {
description 'Run findbugs'
group 'verification'
classes = files("$project.buildDir/intermediates/classes")
source 'src'
classpath = files()
effort 'max'
excludeFilter file('./qa-check/findbugs-exclude.xml')
reports {
xml.enabled = true
html.enabled = false
}
ignoreFailures = true
}
task pmd(type: Pmd) {
description 'Run PMD'
group 'verification'
ruleSetFiles = files("./qa-check/pmd-ruleset.xml")
ruleSets = []
source 'src'
include '**/*.java'
exclude '**/gen/**'
reports {
xml.enabled = false
html.enabled = true
}
ignoreFailures = true
}
apply plugin: 'info.adavis.qualitychecks'

6. OVERVIEW
▸Plugin Skeleton
▸Dependencies
▸Plugin.groovy
▸CustomTask.groovy
▸Publishing
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7. PLUGIN SKELETON
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8. PLUGIN SKELETON
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9. PLUGIN SKELETON
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10. PLUGIN SKELETON
How Gradle finds the Plugin Implementation
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11. PLUGIN SKELETON
implementation-class=info.adavis.qualitychecks.QualityChecksPlugin
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12. DEPENDENCIES
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13. DEPENDENCIES
apply plugin: ‘groovy'
dependencies {
compile gradleApi()
compile localGroovy()
}
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14. DEPENDENCIES
dependencies {
…
testCompile 'junit:junit:4.12'
testCompile ('org.spockframework:spock-core:1.0-groovy-2.4') {
exclude module: 'groovy-all'
}
}
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15. THE CODE
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16. BUT FIRST…
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17. GRADLE BUILD
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PROJECT
TASK TASK TASK
BUILD

18. GRADLE BUILD
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PROJECT
TASK TASK TASK
BUILD
PROJECT
TASK TASK TASK

19. PLUGIN.GROOVY
class CustomPlugin implements Plugin<Project> {
}
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20. PLUGIN.GROOVY
class CustomPlugin implements Plugin<Project> {
@Override
void apply(Project project) {
}
}
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21. QUALITYCHECKSPLUGIN.GROOVY
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22. APPLY METHOD
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void apply(Project project) {
this.project = project
}

23. APPLY METHOD
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void apply(Project project) {
this.project = project
project.extensions.create('qualityChecks', QualityChecksExtension)
}

24. APPLY METHOD
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void apply(Project project) {
this.project = project
project.extensions.create('qualityChecks', QualityChecksExtension)
createConfigFilesIfNeeded()
createConfigFileTasks()
createQualityChecksTasks()
}

25. PROJECT EXTENSION
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class QualityChecksExtension {
String pmdConfigFile = 'quality-checks/pmd-ruleset.xml'
String checkstyleConfigFile = 'quality-checks/checkstyle.xml'
String findBugsExclusionFile = 'quality-checks/findbugs-exclude.xml'
}

26. PROJECT EXTENSION
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class QualityChecksExtension {
String pmdConfigFile = 'quality-checks/pmd-ruleset.xml'
String checkstyleConfigFile = 'quality-checks/checkstyle.xml'
String findBugsExclusionFile = 'quality-checks/findbugs-exclude.xml'
}

27. PROJECT EXTENSION
Back in the application’s build.gradle file…
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qualityChecks {
pmdConfigFile = ‘checks/pmd.xml’
checkstyleConfigFile = ‘checks/checkstyle.xml’
}

28. PROJECT EXTENSION
Back in the application’s build.gradle file…
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qualityChecks {
pmdConfigFile = ‘checks/pmd.xml’
checkstyleConfigFile = ‘checks/checkstyle.xml’
}

29. TASKS
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30. CREATING TASKS
Give it a name and a type
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31. CREATING TASKS
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▸Build on existing task
▸Extend the DefaultTask

32. BUILD ON EXISTING TASK
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33. BUILD ON EXISTING
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34. EXTEND DEFAULT TASK
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35. CUSTOMTASK.GROOVY
class CustomTask extends DefaultTask {
CustomTask() {
group: ‘verification’
}
}
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36. CUSTOMTASK.GROOVY
class CustomTask extends DefaultTask {
CustomTask() {
group: ‘verification’
}
}
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37. CUSTOMTASK.GROOVY
CustomTask() {
group: ‘verification’
onlyIf {
// skip under certain conditions
}
}
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38. CUSTOMTASK.GROOVY
@TaskAction
def defaultAction() {
description: ‘What my task does’
}
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39. CUSTOMTASK.GROOVY
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@TaskAction
def defaultAction() {
description: ‘What my task does’
<do your cool stuff here>
}

40. GRADLE TASK DOCUMENTATION
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41. SO FAR…
▸Plugin Skeleton
▸Dependencies
▸Plugin.groovy
▸CustomTask.groovy
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42. PUBLISHING
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43. PUBLISHING
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44. PUBLISHING
buildscript {
…
dependencies {
classpath "com.gradle.publish:plugin-publish-plugin:0.9.4"
}
}
apply plugin: 'com.gradle.plugin-publish'
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45. PUBLISHING
version = "0.1.3"
group = "info.adavis"
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46. PUBLISHING
pluginBundle {
website = 'https://github.com/adavis/quality-checks'
vcsUrl = 'https://github.com/adavis/quality-checks.git'
description = 'Gradle Plugin for…’
tags = ['Checkstyle', 'FindBugs', 'PMD']
}
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47. PUBLISHING
pluginBundle {
…
plugins {
qualityChecksPlugin {
id = 'info.adavis.qualitychecks'
displayName = 'Quality Checks Plugin'
}
}
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48. @BRWNGRLDEV

49. @BRWNGRLDEV

50. WE’RE DONE…
WRONG!
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51. WE’RE DONE…
TESTS
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52. TESTING - WITH JUNIT
@Before
void setUp() {
projectDir = temporaryFolder.root
projectDir.mkdirs()
}
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53. TESTING - WITH JUNIT
@Before
void setUp() {
projectDir = temporaryFolder.root
projectDir.mkdirs()
project = ProjectBuilder.builder().withProjectDir(projectDir).build()
task = project.tasks.create('writeConfigFile', WriteConfigFileTask)
}
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54. TESTING - WITH JUNIT
@Test
void shouldBeAbleToCreateTask() {
assertTrue(task instanceof WriteConfigFileTask)
}
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55. TESTING - WITH JUNIT
@Test
void pluginShouldBeApplied() {
project.apply(plugin: QualityChecksPlugin)
assertNotNull(project.tasks.findByName(‘mytask’))
}
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56. SPOCK
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57. TESTING - WITH SPOCK
def createCheckstyleTask() {
given: "we have a project"
def project = ProjectBuilder.builder().build()
}

58. TESTING - WITH SPOCK
def createCheckstyleTask() {
and: "we apply the extension"
project.extensions.create('qualityChecks', QualityChecksExtension)
and: "we supply an existing checkstyle config file"
project.qualityChecks.checkstyleConfigFile = File.createTempFile('temp', '.xml').path
}

59. TESTING - WITH SPOCK
def createCheckstyleTask() {
when: "we create a checkstyle task"
def checkstyleTask = project.tasks.create('checkstyle', CheckstyleTask)
}

60. TESTING - WITH SPOCK
def createCheckstyleTask() {
then: "it should not replace our previous file"
checkstyleTask.configFile.name.startsWith('temp')
}

61. TESTING - WITH SPOCK
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62. TESTING - REPORT
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63. TESTING - SPOCK-REPORT
dependencies {
…
testCompile( 'com.athaydes:spock-reports:1.2.12' ) {
transitive = false
}
}
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64. TESTING - SPOCK-REPORT
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65. @BRWNGRLDEV

66. BONUS: README
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67. BONUS: README
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68. BONUS: README
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69. SUMMARY
▸Helps avoid copy/paste horror
▸Simple project structure
▸Extending DefaultTask
▸Testing techniques
▸Easy to publish
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70. THANKS!
@brwngrldev
+AnnyceDavis
www.adavis.info
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