Add support for Gradle's tasksWithType

This commit adds support for configuring several tasks at once using
a type. It also migrates the Kotlin support so that, instead of
configuring compileKotlin and compileTestKotlin, it configures all
tasks of type KotlinCompile at once.

See gh-890

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/gradle/GradleBuild.java

@@ -19,6 +19,7 @@ package io.spring.initializr.generator.buildsystem.gradle;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
@@ -34,6 +35,7 @@ import io.spring.initializr.generator.buildsystem.BuildItemResolver;
  * Gradle build configuration for a project.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
 public class GradleBuild extends Build {
 
@@ -49,6 +51,10 @@ public class GradleBuild extends Build {
 
 	private final Map<String, TaskCustomization> taskCustomizations = new LinkedHashMap<>();
 
+	private final Set<String> importedTypes = new HashSet<>();
+
+	private final Map<String, TaskCustomization> tasksWithTypeCustomizations = new LinkedHashMap<>();
+
 	private final Buildscript buildscript = new Buildscript();
 
 	public GradleBuild(BuildItemResolver buildItemResolver) {
@@ -121,6 +127,24 @@ public class GradleBuild extends Build {
 		return Collections.unmodifiableMap(this.configurationCustomizations);
 	}
 
+	public void addImportedType(String type) {
+		this.importedTypes.add(type);
+	}
+
+	public Set<String> getImportedTypes() {
+		return Collections.unmodifiableSet(this.importedTypes);
+	}
+
+	public void customizeTasksWithType(String typeName,
+			Consumer<TaskCustomization> customizer) {
+		customizer.accept(this.tasksWithTypeCustomizations.computeIfAbsent(typeName,
+				(name) -> new TaskCustomization()));
+	}
+
+	public Map<String, TaskCustomization> getTasksWithTypeCustomizations() {
+		return Collections.unmodifiableMap(this.tasksWithTypeCustomizations);
+	}
+
 	public void customizeTask(String taskName, Consumer<TaskCustomization> customizer) {
 		customizer.accept(this.taskCustomizations.computeIfAbsent(taskName,
 				(name) -> new TaskCustomization()));

initializr-generator/src/main/java/io/spring/initializr/generator/buildsystem/gradle/GradleBuildWriter.java

@@ -47,10 +47,12 @@ import io.spring.initializr.generator.version.VersionReference;
  *
  * @author Andy Wilkinson
  * @author Stephane Nicoll
+ * @author Jean-Baptiste Nizet
  */
 public class GradleBuildWriter {
 
 	public void writeTo(IndentingWriter writer, GradleBuild build) throws IOException {
+		writeImports(writer, build);
 		boolean buildScriptWritten = writeBuildscript(writer, build);
 		writePlugins(writer, build, buildScriptWritten);
 		writeProperty(writer, "group", build.getGroup());
@@ -61,9 +63,18 @@ public class GradleBuildWriter {
 		writeProperties(writer, build);
 		writeDependencies(writer, build);
 		writeBoms(writer, build);
+		writeTasksWithTypeCustomizations(writer, build);
 		writeTaskCustomizations(writer, build);
 	}
 
+	private void writeImports(IndentingWriter writer, GradleBuild build) {
+		build.getImportedTypes().stream().sorted().forEachOrdered(
+				(importedType) -> writer.println("import " + importedType));
+		if (!build.getImportedTypes().isEmpty()) {
+			writer.println();
+		}
+	}
+
 	private boolean writeBuildscript(IndentingWriter writer, GradleBuild build) {
 		List<String> dependencies = build.getBuildscript().getDependencies();
 		Map<String, String> ext = build.getBuildscript().getExt();
@@ -276,6 +287,19 @@ public class GradleBuildWriter {
 		return null;
 	}
 
+	private void writeTasksWithTypeCustomizations(IndentingWriter writer,
+			GradleBuild build) {
+		Map<String, GradleBuild.TaskCustomization> tasksWithTypeCustomizations = build
+				.getTasksWithTypeCustomizations();
+
+		tasksWithTypeCustomizations.forEach((typeName, customization) -> {
+			writer.println();
+			writer.println("tasks.withType(" + typeName + ") {");
+			writer.indented(() -> writeTaskCustomization(writer, customization));
+			writer.println("}");
+		});
+	}
+
 	private void writeTaskCustomizations(IndentingWriter writer, GradleBuild build) {
 		Map<String, TaskCustomization> taskCustomizations = build.getTaskCustomizations();
 		taskCustomizations.forEach((name, customization) -> {

initializr-generator/src/test/java/io/spring/initializr/generator/buildsystem/gradle/GradleBuildWriterTests.java

@@ -33,9 +33,25 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for {@link GradleBuildWriter}
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
 class GradleBuildWriterTests {
 
+	@Test
+	void gradleBuildWithImports() throws IOException {
+		GradleBuild build = new GradleBuild();
+		build.addImportedType(
+				"org.springframework.boot.gradle.tasks.buildinfo.BuildInfo");
+		build.addImportedType("org.jetbrains.kotlin.gradle.tasks.KotlinCompile");
+		// same import added twice on purpose
+		build.addImportedType("org.jetbrains.kotlin.gradle.tasks.KotlinCompile");
+
+		List<String> lines = generateBuild(build);
+		assertThat(lines.subList(0, 3)).containsExactly(
+				"import org.jetbrains.kotlin.gradle.tasks.KotlinCompile",
+				"import org.springframework.boot.gradle.tasks.buildinfo.BuildInfo", "");
+	}
+
 	@Test
 	void gradleBuildWithCoordinates() throws IOException {
 		GradleBuild build = new GradleBuild();
@@ -139,6 +155,22 @@ class GradleBuildWriterTests {
 		assertThat(lines).doesNotContain("repositories {");
 	}
 
+	@Test
+	void gradleBuildWithTaskWithTypesCustomizedWithNestedAssignments()
+			throws IOException {
+		GradleBuild build = new GradleBuild();
+		build.customizeTasksWithType("KotlinCompile", (task) -> {
+			task.nested("kotlinOptions", (kotlinOptions) -> {
+				kotlinOptions.set("freeCompilerArgs", "['-Xjsr305=strict']");
+				kotlinOptions.set("jvmTarget", "'1.8'");
+			});
+		});
+		List<String> lines = generateBuild(build);
+		assertThat(lines).containsSequence("tasks.withType(KotlinCompile) {",
+				"    kotlinOptions {", "        freeCompilerArgs = ['-Xjsr305=strict']",
+				"        jvmTarget = '1.8'", "    }", "}");
+	}
+
 	@Test
 	void gradleBuildWithTaskCustomizedWithInvocations() throws IOException {
 		GradleBuild build = new GradleBuild();