This document demonstrates how to create a Gradle plugin that defines tasks to run various code quality checks like Checkstyle, FindBugs, and PMD. It applies the necessary plugins, defines a project extension to configure file paths, and creates tasks that integrate with the underlying checkstyle, findbugs, and pmd libraries. The plugin also shows how to test the plugin functionality using JUnit and Spock and publish the plugin so it can be used in other Gradle projects.

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
▸Gradle Task
▸Plugin Skeleton
▸Dependencies
▸Plugin Classes
▸Publishing
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7. GRADLE TASKS
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8. GRADLE BUILD
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PROJECT
TASK TASK TASK
BUILD

9. GRADLE BUILD LIFECYCLE
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TASK
TASK TASK
TASK TASK

10. EXAMPLE TASK
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I want to ask you for your name.
1. Say Hello
2. Ask for your name

11. DEFINING A TASK
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task sayHello {
doLast {
println “Hello.”
}
}

12. DEFINING A TASK
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task askYourName {
dependsOn “sayHello”
doLast {
println “What is your name?”
}
}
task sayHello {
doLast {
println “Hello.”
}
}

13. EXECUTING A TASK
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14. PLUGIN
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PROJECT
TASK TASK TASK
BUILD
TASK TASK
TASK
PLUGIN

15. CREATING PLUGINS
▸build.gradle file
▸buildSrc directory
▸separate project

16. PLUGIN - BUILD.GRADLE FILE
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17. PLUGIN - BUILD.GRADLE FILE
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18. 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'

19. PLUGIN SKELETON
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20. PLUGIN SKELETON
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21. PLUGIN SKELETON
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22. PLUGIN SKELETON
How Gradle finds the Plugin Implementation
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23. DEPENDENCIES
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24. DEPENDENCIES
apply plugin: ‘groovy'
dependencies {
compile gradleApi()
compile localGroovy()
}
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25. 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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26. THE CODE
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27. PLUGIN.GROOVY
class CustomPlugin implements Plugin<Project> {
}
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28. PLUGIN.GROOVY
class CustomPlugin implements Plugin<Project> {
@Override
void apply(Project project) {
}
}
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29. QUALITYCHECKSPLUGIN.GROOVY
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30. APPLY METHOD
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void apply(Project project) {
this.project = project
}

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

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

33. 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'
}

34. 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'
}

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

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

37. TASKS
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38. CREATING TASKS
Give it a name and a type
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39. CREATING TASKS
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Build on existing task
Extend the DefaultTask

40. BUILD ON EXISTING TASK
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41. BUILD ON EXISTING
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42. EXTEND DEFAULT TASK
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43. CUSTOMTASK.GROOVY
class CustomTask extends DefaultTask {
CustomTask() {
group: ‘verification’
}
}
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44. CUSTOMTASK.GROOVY
class CustomTask extends DefaultTask {
CustomTask() {
group: ‘verification’
}
}
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45. CUSTOMTASK.GROOVY
CustomTask() {
group: ‘verification’
onlyIf {
// skip under certain conditions
}
}
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46. CUSTOMTASK.GROOVY
@TaskAction
def defaultAction() {
description: ‘What my task does’
}
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47. CUSTOMTASK.GROOVY
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@TaskAction
def defaultAction() {
description: ‘What my task does’
<do your cool stuff here>
}

48. GRADLE TASK DOCUMENTATION
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49. SO FAR…
▸Gradle Tasks
▸Plugin Skeleton
▸Dependencies
▸Plugin Classes
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50. PUBLISHING
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51. PUBLISHING
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52. PUBLISHING
buildscript {
…
dependencies {
classpath "com.gradle.publish:plugin-publish-plugin:0.9.4"
}
}
apply plugin: 'com.gradle.plugin-publish'
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53. PUBLISHING
version = "0.1.3"
group = "info.adavis"
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54. 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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55. PUBLISHING
pluginBundle {
…
plugins {
qualityChecksPlugin {
id = 'info.adavis.qualitychecks'
displayName = 'Quality Checks Plugin'
}
}
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56. @BRWNGRLDEV

57. @BRWNGRLDEV

58. WE’RE DONE…
WRONG!
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59. WE’RE DONE…
TESTS
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60. TESTING - WITH JUNIT
@Before
void setUp()
{
project = ProjectBuilder.builder().build()
task = project.tasks.create('writeConfigFile', WriteConfigFileTask)
}
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61. TESTING - WITH JUNIT
@Test
void shouldBeAbleToCreateTask()
{
assertTrue(task instanceof WriteConfigFileTask)
}
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62. TESTING - WITH JUNIT
@Test
void pluginShouldBeApplied()
{
project.apply(plugin: QualityChecksPlugin)
assertNotNull(project.tasks.findByName(‘mytask’))
}
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63. SPOCK
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64. TESTING - WITH SPOCK
def createCheckstyleTask() {
given: "we have a project"
def project = ProjectBuilder.builder().build()
}

65. 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
}

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

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

68. TESTING - WITH SPOCK
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69. TESTING - REPORT
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70. TESTING - SPOCK-REPORT
dependencies {
…
testCompile( 'com.athaydes:spock-reports:1.2.12' ) {
transitive = false
}
}
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71. TESTING - SPOCK-REPORT
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72. @BRWNGRLDEV

73. BONUS: README
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74. BONUS: README
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75. BONUS: README
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76. SUMMARY
▸Gradle Build Basics
▸Creating Task
▸Benefits of Plugins
▸Testing techniques
▸Easy to publish
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77. THANKS!
@brwngrldev
+AnnyceDavis
www.adavis.info
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