Improve Gradle integration

This commit adds improved Gradle integration. The Java Format Gradle plugin now: - Reacts to the Checkstyle plugin being applied by adding a dependency on spring-javaformat-checkstyle - Provide a DSL extension that can be used to: - Apply the default checkstyle.xml configuration - Opt out of the automatic dependency configuration Closes gh-443 Closes gh-453

Author: wilkinsona

README.adoc

@@ -162,34 +162,48 @@ tasks.withType(io.spring.javaformat.gradle.tasks.CheckFormat) {
 
 
 ==== Checkstyle
-To enforce Checkstyle conventions, add the `checkstyle` plugin and include a dependency on `spring-javaformat-checkstyle`:
+To enforce Checkstyle conventions, apply the Checkstyle plugin in addition to the `io.spring.javaformat` plugin:
 
 [source,groovy,indent=0,subs="normal"]
 ----
 plugins {
+id "io.spring.javaformat" version "{release-version}"
 id "checkstyle"
 }
 
+The Spring Java Format plugin will react to the Checkstyle plugin being applied and configure the necessary dependencies in the `checkstyle` configuration.
+
+You should also configure Checkstyle's tool version:
+
+[source,groovy,indent=0,subs="normal"]
+----
 checkstyle {
 toolVersion = "{checkstyle-version}"
 }
+----
+
+To configure Checkstyle to use the default Spring checks, add the following configuration:
 
-dependencies {
-checkstyle("io.spring.javaformat:spring-javaformat-checkstyle:{release-version}")
+[source,groovy,indent=0,subs="normal"]
+----
+springJavaFormat {
+checkstyle {
+applyDefaultConfig()
+}
 }
 ----
 
-To use the Spring checks, your `checkstyle.xml` file should look like this:
+Alternatively, provide your own `checkstyle.xml` that configures the `io.spring.javaformat.checkstyle.SpringChecks` module.
 
-[source,xml,indent=0]
+If you want to use both Spring Java Format and Checkstyle but you do not want to use Spring Java Format's checks, disable the aforementioned dependency configuration:
+
+[source,groovy,indent=0,subs="normal"]
 ----
-<?xml version="1.0"?>
-<!DOCTYPE module PUBLIC
-"-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
-"https://checkstyle.org/dtds/configuration_1_3.dtd">
-<module name="com.puppycrawl.tools.checkstyle.Checker">
-<module name="io.spring.javaformat.checkstyle.SpringChecks" />
-</module>
+springJavaFormat {
+checkstyle {
+configureDependencies = false
+}
+}
 ----
 
 

spring-javaformat-gradle/spring-javaformat-gradle-plugin/pom.xml

@@ -115,6 +115,12 @@
 <artifactId>spring-javaformat-formatter-shaded</artifactId>
 <version>${project.version}</version>
 </dependency>
+<!-- Test -->
+<dependency>
+<groupId>io.spring.javaformat</groupId>
+<artifactId>spring-javaformat-checkstyle</artifactId>
+<version>${project.version}</version>
+</dependency>
 </dependencies>
 <profiles>
 <profile>

spring-javaformat-gradle/spring-javaformat-gradle-plugin/src/main/java/io/spring/javaformat/gradle/SpringJavaFormatExtension.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2017-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.javaformat.gradle;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+import javax.inject.Inject;
+
+import org.gradle.api.Action;
+import org.gradle.api.Project;
+import org.gradle.api.plugins.quality.CheckstyleExtension;
+import org.gradle.api.provider.Property;
+import org.gradle.api.resources.TextResource;
+
+/**
+ * DSL extension for Spring Java Format.
+ *
+ * @author Andy Wilkinson
+ */
+public abstract class SpringJavaFormatExtension {
+
+private final Checkstyle checkstyle;
+
+@Inject
+public SpringJavaFormatExtension(Project project) {
+this.checkstyle = project.getObjects().newInstance(Checkstyle.class, project);
+this.checkstyle.getConfigureDependencies().convention(true);
+}
+
+public Checkstyle getCheckstyle() {
+return this.checkstyle;
+}
+
+public void checkstyle(Action<Checkstyle> action) {
+action.execute(this.checkstyle);
+}
+
+public abstract static class Checkstyle {
+
+private final Project project;
+
+@Inject
+public Checkstyle(Project project) {
+this.project = project;
+}
+
+/**
+ * Property that controls whether Checkstyle's dependencies should be configured to
+ * use Spring Java Format's checks.
+ * @return the property
+ */
+public abstract Property<Boolean> getConfigureDependencies();
+
+/**
+ * Applies Spring Java Format's default Checkstyle config, enabling all Spring checks.
+ * @see CheckstyleExtension#setConfig(TextResource)
+ */
+public void applyDefaultConfig() {
+CheckstyleExtension extension = this.project.getExtensions().getByType(CheckstyleExtension.class);
+StringWriter defaultConfig = new StringWriter();
+PrintWriter writer = new PrintWriter(defaultConfig);
+writer.println("<?xml version=\"1.0\"?>");
+writer.println("<!DOCTYPE module PUBLIC");
+writer.println("\"-//Checkstyle//DTD Checkstyle Configuration 1.3//EN\"");
+writer.println("\"https://checkstyle.org/dtds/configuration_1_3.dtd\">");
+writer.println("<module name=\"com.puppycrawl.tools.checkstyle.Checker\">");
+writer.println("	<module name=\"io.spring.javaformat.checkstyle.SpringChecks\">");
+writer.println("	</module>");
+writer.println("</module>");
+extension.setConfig(this.project.getResources().getText().fromString(defaultConfig.toString()));
+}
+
+}
+
+}

spring-javaformat-gradle/spring-javaformat-gradle-plugin/src/main/java/io/spring/javaformat/gradle/SpringJavaFormatPlugin.java

@@ -17,17 +17,24 @@
 package io.spring.javaformat.gradle;
 
 import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
 
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
 import org.gradle.api.Task;
+import org.gradle.api.artifacts.Dependency;
+import org.gradle.api.artifacts.DependencySet;
 import org.gradle.api.plugins.JavaBasePlugin;
 import org.gradle.api.plugins.JavaPluginExtension;
+import org.gradle.api.plugins.quality.CheckstyleExtension;
+import org.gradle.api.plugins.quality.CheckstylePlugin;
 import org.gradle.api.tasks.SourceSet;
 import org.gradle.api.tasks.TaskContainer;
 import org.gradle.api.tasks.TaskProvider;
 
 import io.spring.javaformat.config.JavaFormatConfig;
+import io.spring.javaformat.formatter.Formatter;
 import io.spring.javaformat.gradle.tasks.CheckFormat;
 import io.spring.javaformat.gradle.tasks.Format;
 import io.spring.javaformat.gradle.tasks.FormatterTask;
@@ -46,6 +53,13 @@ public class SpringJavaFormatPlugin implements Plugin<Project> {
 public void apply(Project project) {
 this.project = project;
 addSourceTasks();
+SpringJavaFormatExtension extension = registerExtension();
+new CheckstyleConfigurer(project, extension).apply();
+}
+
+private SpringJavaFormatExtension registerExtension() {
+SpringJavaFormatExtension extension = this.project.getExtensions().create("springJavaFormat", SpringJavaFormatExtension.class);
+return extension;
 }
 
 private void addSourceTasks() {
@@ -90,4 +104,39 @@ private <T extends FormatterTask> TaskProvider<T> addFormatterTask(SourceSet sou
 return provider;
 }
 
+private static final class CheckstyleConfigurer {
+
+private final Project project;
+
+private final SpringJavaFormatExtension extension;
+
+private CheckstyleConfigurer(Project project, SpringJavaFormatExtension extension) {
+this.project = project;
+this.extension = extension;
+}
+
+private void apply() {
+this.project.getPlugins().withType(CheckstylePlugin.class).configureEach((checkstylePlugin) -> {
+CheckstyleExtension checkstyle = this.project.getExtensions().getByType(CheckstyleExtension.class);
+DependencySet checkstyleDependencies = this.project.getConfigurations().getByName("checkstyle").getDependencies();
+checkstyleDependencies.addAllLater(this.project.provider(() -> checkstyleDependencies(checkstyle)));
+});
+}
+
+private List<Dependency> checkstyleDependencies(CheckstyleExtension checkstyle) {
+List<Dependency> dependencies = new ArrayList<>();
+if (configuringCheckstyleDependencies()) {
+dependencies.add(this.project.getDependencies().create("com.puppycrawl.tools:checkstyle:" + checkstyle.getToolVersion()));
+dependencies.add(this.project.getDependencies().create("io.spring.javaformat:spring-javaformat-checkstyle:"
++ Formatter.class.getPackage().getImplementationVersion()));
+}
+return dependencies;
+}
+
+private boolean configuringCheckstyleDependencies() {
+return Boolean.TRUE.equals(this.extension.getCheckstyle().getConfigureDependencies().get());
+}
+
+}
+
 }

spring-javaformat-gradle/spring-javaformat-gradle-plugin/src/test/java/io/spring/javaformat/gradle/CheckstyleTests.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2017-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.javaformat.gradle;
+
+import org.gradle.testkit.runner.BuildResult;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import io.spring.javaformat.gradle.testkit.GradleBuild;
+import io.spring.javaformat.gradle.testkit.GradleBuildExtension;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@ExtendWith(GradleBuildExtension.class)
+class CheckstyleTests {
+
+private final GradleBuild gradleBuild = new GradleBuild();
+
+@Test
+void configureCheckstyle() {
+BuildResult result = this.gradleBuild.source("src/test/resources/checkstyle-configure").build("checkstyleDependencies");
+assertThat(result.getOutput()).contains("io.spring.javaformat:spring-javaformat-checkstyle:");
+assertThat(result.getOutput()).contains("com.puppycrawl.tools:checkstyle:8.45.1");
+}
+
+@Test
+void configureCheckstyleWithCustomToolVersion() {
+BuildResult result = this.gradleBuild.source("src/test/resources/checkstyle-configure-with-custom-tool-version").build("checkstyleDependencies");
+assertThat(result.getOutput()).contains("io.spring.javaformat:spring-javaformat-checkstyle:");
+assertThat(result.getOutput()).contains("com.puppycrawl.tools:checkstyle:10.26.1");
+}
+
+@Test
+void doNotConfigureCheckstyle() {
+BuildResult result = this.gradleBuild.source("src/test/resources/checkstyle-do-not-configure").build("checkstyleDependencies");
+assertThat(result.getOutput()).doesNotContain("spring-javaformat-checkstyle");
+}
+
+@Test
+void applyDefaultConfigToCheckstyle() {
+BuildResult result = this.gradleBuild.source("src/test/resources/checkstyle-apply-default-config").build("checkstyleConfig");
+assertThat(result.getOutput()).contains("<module name=\"io.spring.javaformat.checkstyle.SpringChecks\">");
+}
+
+}

spring-javaformat-gradle/spring-javaformat-gradle-plugin/src/test/resources/checkstyle-apply-default-config/build.gradle

@@ -0,0 +1,27 @@
+buildscript {
+dependencies {
+classpath files(pluginClasspath.split(','))
+}
+}
+
+apply plugin: 'checkstyle'
+apply plugin: 'java'
+apply plugin: 'io.spring.javaformat'
+
+sourceCompatibility = 1.8
+
+repositories {
+mavenCentral()
+}
+
+springJavaFormat {
+checkstyle {
+applyDefaultConfig()
+}
+}
+
+tasks.register("checkstyleConfig") {
+doFirst {
+println checkstyle.config.asString()
+}
+}

spring-javaformat-gradle/spring-javaformat-gradle-plugin/src/test/resources/checkstyle-configure-with-custom-tool-version/build.gradle

@@ -0,0 +1,25 @@
+buildscript {
+dependencies {
+classpath files(pluginClasspath.split(','))
+}
+}
+
+apply plugin: 'checkstyle'
+apply plugin: 'java'
+apply plugin: 'io.spring.javaformat'
+
+sourceCompatibility = 1.8
+
+repositories {
+mavenCentral()
+}
+
+checkstyle {
+toolVersion = "10.26.1"
+}
+
+tasks.register("checkstyleDependencies") {
+doFirst {
+configurations.checkstyle.dependencies.each { println "${it.group}:${it.name}:${it.version}" }
+}
+}

spring-javaformat-gradle/spring-javaformat-gradle-plugin/src/test/resources/checkstyle-configure/build.gradle

@@ -0,0 +1,21 @@
+buildscript {
+dependencies {
+classpath files(pluginClasspath.split(','))
+}
+}
+
+apply plugin: 'checkstyle'
+apply plugin: 'java'
+apply plugin: 'io.spring.javaformat'
+
+sourceCompatibility = 1.8
+
+repositories {
+mavenCentral()
+}
+
+tasks.register("checkstyleDependencies") {
+doFirst {
+configurations.checkstyle.dependencies.each { println "${it.group}:${it.name}:${it.version}" }
+}
+}