Add Kotlin DSL examples to Gradle Plugin's documentation

See gh-14585

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/DSL.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2012-2018 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
+ *
+ *      http://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 org.springframework.boot.gradle.docs;
+
+/**
+ * The DSLs supported by Gradle and demonstrated in the documentation samples
+ */
+public enum DSL {
+
+	GROOVY("Groovy", ".gradle"), KOTLIN("Kotlin", ".gradle.kts");
+
+	private final String name;
+
+	private final String extension;
+
+	DSL(String name, String extension) {
+		this.name = name;
+		this.extension = extension;
+	}
+
+	/**
+	 * Gets the user-friendly name of the DSL
+	 */
+	public String getName() {
+		return this.name;
+	}
+
+	/**
+	 * Gets the file extension of build scripts (starting with a dot)
+	 */
+	public String getExtension() {
+		return this.extension;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/GettingStartedDocumentationTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot.gradle.docs;
 
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.runner.RunWith;
 
 import org.springframework.boot.gradle.testkit.GradleBuild;
 
@@ -25,19 +26,23 @@ import org.springframework.boot.gradle.testkit.GradleBuild;
  * Tests for the getting started documentation.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
+@RunWith(GradleMultiDslSuite.class)
 public class GettingStartedDocumentationTests {
 
 	@Rule
-	public GradleBuild gradleBuild = new GradleBuild();
+	public GradleBuild gradleBuild;
+
+	public DSL dsl;
 
 	// NOTE: We can't run any `apply-plugin` tests because during a release the
 	// jar won't be there
 
 	@Test
 	public void typicalPluginsAppliesExceptedPlugins() {
-		this.gradleBuild.script("src/main/gradle/getting-started/typical-plugins.gradle")
-				.build("verify");
+		this.gradleBuild.script("src/main/gradle/getting-started/typical-plugins"
+				+ this.dsl.getExtension()).build("verify");
 	}
 
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/GradleMultiDslSuite.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2012-2018 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
+ *
+ *      http://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 org.springframework.boot.gradle.docs;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.gradle.api.Rule;
+import org.junit.runner.Runner;
+import org.junit.runners.BlockJUnit4ClassRunner;
+import org.junit.runners.Suite;
+import org.junit.runners.model.FrameworkMethod;
+import org.junit.runners.model.InitializationError;
+
+import org.springframework.boot.gradle.testkit.GradleBuild;
+
+/**
+ * Custom {@link Suite} that runs tests against the Groovy and the Kotlin DSLs. Test
+ * classes using the suite must have a public {@link DSL} field named {@code dsl} and a
+ * public {@link GradleBuild} field named {@code gradleBuild} and annotated with
+ * {@link Rule}
+ *
+ * @author Jean-Baptiste Nizet
+ */
+public final class GradleMultiDslSuite extends Suite {
+
+	public GradleMultiDslSuite(Class<?> clazz) throws InitializationError {
+		super(clazz, createRunners(clazz));
+	}
+
+	private static List<Runner> createRunners(Class<?> clazz) throws InitializationError {
+		List<Runner> runners = new ArrayList<>();
+		runners.add(new GradleDslClassRunner(clazz, new GradleBuild(), DSL.GROOVY));
+		runners.add(new GradleDslClassRunner(clazz,
+				new GradleBuild().withMinimalGradleVersionForKotlinDSL(), DSL.KOTLIN));
+		return runners;
+	}
+
+	private static final class GradleDslClassRunner extends BlockJUnit4ClassRunner {
+
+		private final GradleBuild gradleBuild;
+
+		private final DSL dsl;
+
+		private GradleDslClassRunner(Class<?> klass, GradleBuild gradleBuild, DSL dsl)
+				throws InitializationError {
+			super(klass);
+			this.gradleBuild = gradleBuild;
+			this.dsl = dsl;
+		}
+
+		@Override
+		protected Object createTest() throws Exception {
+			Object test = super.createTest();
+			configureTest(test);
+			return test;
+		}
+
+		private void configureTest(Object test) throws Exception {
+			test.getClass().getField("gradleBuild").set(test, this.gradleBuild);
+			test.getClass().getField("dsl").set(test, this.dsl);
+		}
+
+		@Override
+		protected String getName() {
+			return this.dsl.getName() + " DSL";
+		}
+
+		@Override
+		protected String testName(FrameworkMethod method) {
+			return method.getName() + " [" + getName() + "]";
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/IntegratingWithActuatorDocumentationTests.java

@@ -23,6 +23,7 @@ import java.util.Properties;
 
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.runner.RunWith;
 
 import org.springframework.boot.gradle.testkit.GradleBuild;
 
@@ -32,16 +33,21 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for the generating build info documentation.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
+@RunWith(GradleMultiDslSuite.class)
 public class IntegratingWithActuatorDocumentationTests {
 
 	@Rule
-	public GradleBuild gradleBuild = new GradleBuild();
+	public GradleBuild gradleBuild;
+
+	public DSL dsl;
 
 	@Test
 	public void basicBuildInfo() throws IOException {
-		this.gradleBuild.script(
-				"src/main/gradle/integrating-with-actuator/build-info-basic.gradle")
+		this.gradleBuild
+				.script("src/main/gradle/integrating-with-actuator/build-info-basic"
+						+ this.dsl.getExtension())
 				.build("bootBuildInfo");
 		assertThat(new File(this.gradleBuild.getProjectDir(),
 				"build/resources/main/META-INF/build-info.properties")).isFile();
@@ -50,7 +56,8 @@ public class IntegratingWithActuatorDocumentationTests {
 	@Test
 	public void buildInfoCustomValues() throws IOException {
 		this.gradleBuild.script(
-				"src/main/gradle/integrating-with-actuator/build-info-custom-values.gradle")
+				"src/main/gradle/integrating-with-actuator/build-info-custom-values"
+						+ this.dsl.getExtension())
 				.build("bootBuildInfo");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/resources/main/META-INF/build-info.properties");
@@ -64,8 +71,9 @@ public class IntegratingWithActuatorDocumentationTests {
 
 	@Test
 	public void buildInfoAdditional() throws IOException {
-		this.gradleBuild.script(
-				"src/main/gradle/integrating-with-actuator/build-info-additional.gradle")
+		this.gradleBuild
+				.script("src/main/gradle/integrating-with-actuator/build-info-additional"
+						+ this.dsl.getExtension())
 				.build("bootBuildInfo");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/resources/main/META-INF/build-info.properties");

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/ManagingDependenciesDocumentationTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot.gradle.docs;
 
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.runner.RunWith;
 
 import org.springframework.boot.gradle.testkit.GradleBuild;
 
@@ -27,32 +28,49 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for the managing dependencies documentation.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
+@RunWith(GradleMultiDslSuite.class)
 public class ManagingDependenciesDocumentationTests {
 
 	@Rule
-	public GradleBuild gradleBuild = new GradleBuild();
+	public GradleBuild gradleBuild;
+
+	public DSL dsl;
 
 	@Test
 	public void dependenciesExampleEvaluatesSuccessfully() {
-		this.gradleBuild
-				.script("src/main/gradle/managing-dependencies/dependencies.gradle")
-				.build();
+		this.gradleBuild.script("src/main/gradle/managing-dependencies/dependencies"
+				+ this.dsl.getExtension()).build();
 	}
 
 	@Test
 	public void customManagedVersions() {
-		assertThat(this.gradleBuild
-				.script("src/main/gradle/managing-dependencies/custom-version.gradle")
-				.build("slf4jVersion").getOutput()).contains("1.7.20");
+		assertThat(
+				this.gradleBuild
+						.script("src/main/gradle/managing-dependencies/custom-version"
+								+ this.dsl.getExtension())
+						.build("slf4jVersion").getOutput()).contains("1.7.20");
 	}
 
 	@Test
 	public void dependencyManagementInIsolation() {
 		assertThat(this.gradleBuild
-				.script("src/main/gradle/managing-dependencies/configure-bom.gradle")
+				.script("src/main/gradle/managing-dependencies/configure-bom"
+						+ this.dsl.getExtension())
 				.build("dependencyManagement").getOutput())
 						.contains("org.springframework.boot:spring-boot-starter ");
 	}
 
+	@Test
+	public void dependencyManagementInIsolationWithPluginsBlock() {
+		if (this.dsl == DSL.KOTLIN) {
+			assertThat(this.gradleBuild.script(
+					"src/main/gradle/managing-dependencies/configure-bom-with-plugins"
+							+ this.dsl.getExtension())
+					.build("dependencyManagement").getOutput())
+							.contains("org.springframework.boot:spring-boot-starter ");
+		}
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/PackagingDocumentationTests.java

@@ -25,6 +25,7 @@ import java.util.jar.JarFile;
 
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.runner.RunWith;
 
 import org.springframework.boot.gradle.testkit.GradleBuild;
 import org.springframework.util.FileCopyUtils;
@@ -35,22 +36,26 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for the packaging documentation.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
+@RunWith(GradleMultiDslSuite.class)
 public class PackagingDocumentationTests {
 
 	@Rule
-	public GradleBuild gradleBuild = new GradleBuild();
+	public GradleBuild gradleBuild;
+
+	public DSL dsl;
 
 	@Test
 	public void warContainerDependencyEvaluatesSuccessfully() {
-		this.gradleBuild
-				.script("src/main/gradle/packaging/war-container-dependency.gradle")
-				.build();
+		this.gradleBuild.script("src/main/gradle/packaging/war-container-dependency"
+				+ this.dsl.getExtension()).build();
 	}
 
 	@Test
 	public void bootJarMainClass() throws IOException {
-		this.gradleBuild.script("src/main/gradle/packaging/boot-jar-main-class.gradle")
+		this.gradleBuild.script(
+				"src/main/gradle/packaging/boot-jar-main-class" + this.dsl.getExtension())
 				.build("bootJar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
@@ -63,9 +68,8 @@ public class PackagingDocumentationTests {
 
 	@Test
 	public void bootJarManifestMainClass() throws IOException {
-		this.gradleBuild
-				.script("src/main/gradle/packaging/boot-jar-manifest-main-class.gradle")
-				.build("bootJar");
+		this.gradleBuild.script("src/main/gradle/packaging/boot-jar-manifest-main-class"
+				+ this.dsl.getExtension()).build("bootJar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
 		assertThat(file).isFile();
@@ -77,9 +81,8 @@ public class PackagingDocumentationTests {
 
 	@Test
 	public void applicationPluginMainClass() throws IOException {
-		this.gradleBuild
-				.script("src/main/gradle/packaging/application-plugin-main-class.gradle")
-				.build("bootJar");
+		this.gradleBuild.script("src/main/gradle/packaging/application-plugin-main-class"
+				+ this.dsl.getExtension()).build("bootJar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
 		assertThat(file).isFile();
@@ -91,9 +94,8 @@ public class PackagingDocumentationTests {
 
 	@Test
 	public void springBootDslMainClass() throws IOException {
-		this.gradleBuild
-				.script("src/main/gradle/packaging/spring-boot-dsl-main-class.gradle")
-				.build("bootJar");
+		this.gradleBuild.script("src/main/gradle/packaging/spring-boot-dsl-main-class"
+				+ this.dsl.getExtension()).build("bootJar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
 		assertThat(file).isFile();
@@ -107,9 +109,8 @@ public class PackagingDocumentationTests {
 	public void bootWarIncludeDevtools() throws IOException {
 		new File(this.gradleBuild.getProjectDir(),
 				"spring-boot-devtools-1.2.3.RELEASE.jar").createNewFile();
-		this.gradleBuild
-				.script("src/main/gradle/packaging/boot-war-include-devtools.gradle")
-				.build("bootWar");
+		this.gradleBuild.script("src/main/gradle/packaging/boot-war-include-devtools"
+				+ this.dsl.getExtension()).build("bootWar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".war");
 		assertThat(file).isFile();
@@ -121,9 +122,8 @@ public class PackagingDocumentationTests {
 
 	@Test
 	public void bootJarRequiresUnpack() throws IOException {
-		this.gradleBuild
-				.script("src/main/gradle/packaging/boot-jar-requires-unpack.gradle")
-				.build("bootJar");
+		this.gradleBuild.script("src/main/gradle/packaging/boot-jar-requires-unpack"
+				+ this.dsl.getExtension()).build("bootJar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
 		assertThat(file).isFile();
@@ -136,9 +136,8 @@ public class PackagingDocumentationTests {
 
 	@Test
 	public void bootJarIncludeLaunchScript() throws IOException {
-		this.gradleBuild
-				.script("src/main/gradle/packaging/boot-jar-include-launch-script.gradle")
-				.build("bootJar");
+		this.gradleBuild.script("src/main/gradle/packaging/boot-jar-include-launch-script"
+				+ this.dsl.getExtension()).build("bootJar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
 		assertThat(file).isFile();
@@ -148,8 +147,9 @@ public class PackagingDocumentationTests {
 
 	@Test
 	public void bootJarLaunchScriptProperties() throws IOException {
-		this.gradleBuild.script(
-				"src/main/gradle/packaging/boot-jar-launch-script-properties.gradle")
+		this.gradleBuild
+				.script("src/main/gradle/packaging/boot-jar-launch-script-properties"
+						+ this.dsl.getExtension())
 				.build("bootJar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
@@ -164,9 +164,8 @@ public class PackagingDocumentationTests {
 				"src/custom.script");
 		customScriptFile.getParentFile().mkdirs();
 		FileCopyUtils.copy("custom", new FileWriter(customScriptFile));
-		this.gradleBuild
-				.script("src/main/gradle/packaging/boot-jar-custom-launch-script.gradle")
-				.build("bootJar");
+		this.gradleBuild.script("src/main/gradle/packaging/boot-jar-custom-launch-script"
+				+ this.dsl.getExtension()).build("bootJar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");
 		assertThat(file).isFile();
@@ -175,9 +174,8 @@ public class PackagingDocumentationTests {
 
 	@Test
 	public void bootWarPropertiesLauncher() throws IOException {
-		this.gradleBuild
-				.script("src/main/gradle/packaging/boot-war-properties-launcher.gradle")
-				.build("bootWar");
+		this.gradleBuild.script("src/main/gradle/packaging/boot-war-properties-launcher"
+				+ this.dsl.getExtension()).build("bootWar");
 		File file = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".war");
 		assertThat(file).isFile();
@@ -188,8 +186,9 @@ public class PackagingDocumentationTests {
 	}
 
 	@Test
-	public void bootJarAndJar() throws IOException {
-		this.gradleBuild.script("src/main/gradle/packaging/boot-jar-and-jar.gradle")
+	public void bootJarAndJar() {
+		this.gradleBuild.script(
+				"src/main/gradle/packaging/boot-jar-and-jar" + this.dsl.getExtension())
 				.build("assemble");
 		File jar = new File(this.gradleBuild.getProjectDir(),
 				"build/libs/" + this.gradleBuild.getProjectDir().getName() + ".jar");

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/PublishingDocumentationTests.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.runner.RunWith;
 
 import org.springframework.boot.gradle.testkit.GradleBuild;
 
@@ -29,26 +30,32 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for the publishing documentation.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
+@RunWith(GradleMultiDslSuite.class)
 public class PublishingDocumentationTests {
 
 	@Rule
-	public GradleBuild gradleBuild = new GradleBuild();
+	public GradleBuild gradleBuild;
+
+	public DSL dsl;
 
 	@Test
 	public void mavenUpload() throws IOException {
-		assertThat(this.gradleBuild.script("src/main/gradle/publishing/maven.gradle")
+		assertThat(this.gradleBuild
+				.script("src/main/gradle/publishing/maven" + this.dsl.getExtension())
 				.build("deployerRepository").getOutput())
 						.contains("https://repo.example.com");
 	}
 
 	@Test
 	public void mavenPublish() throws IOException {
-		assertThat(
-				this.gradleBuild.script("src/main/gradle/publishing/maven-publish.gradle")
-						.build("publishingConfiguration").getOutput())
-								.contains("MavenPublication")
-								.contains("https://repo.example.com");
+		assertThat(this.gradleBuild
+				.script("src/main/gradle/publishing/maven-publish"
+						+ this.dsl.getExtension())
+				.build("publishingConfiguration").getOutput())
+						.contains("MavenPublication")
+						.contains("https://repo.example.com");
 	}
 
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/docs/RunningDocumentationTests.java

@@ -21,6 +21,7 @@ import java.io.IOException;
 
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.runner.RunWith;
 
 import org.springframework.boot.gradle.testkit.GradleBuild;
 
@@ -30,23 +31,29 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for the documentation about running a Spring Boot application.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
+@RunWith(GradleMultiDslSuite.class)
 public class RunningDocumentationTests {
 
 	@Rule
-	public GradleBuild gradleBuild = new GradleBuild();
+	public GradleBuild gradleBuild;
+
+	public DSL dsl;
 
 	@Test
 	public void bootRunMain() throws IOException {
-		assertThat(this.gradleBuild.script("src/main/gradle/running/boot-run-main.gradle")
+		assertThat(this.gradleBuild
+				.script("src/main/gradle/running/boot-run-main" + this.dsl.getExtension())
 				.build("configuredMainClass").getOutput())
 						.contains("com.example.ExampleApplication");
 	}
 
 	@Test
-	public void applicationPluginMainClassName() throws IOException {
-		assertThat(this.gradleBuild.script(
-				"src/main/gradle/running/application-plugin-main-class-name.gradle")
+	public void applicationPluginMainClassName() {
+		assertThat(this.gradleBuild
+				.script("src/main/gradle/running/application-plugin-main-class-name"
+						+ this.dsl.getExtension())
 				.build("configuredMainClass").getOutput())
 						.contains("com.example.ExampleApplication");
 	}
@@ -54,7 +61,8 @@ public class RunningDocumentationTests {
 	@Test
 	public void springBootDslMainClassName() throws IOException {
 		assertThat(this.gradleBuild
-				.script("src/main/gradle/running/spring-boot-dsl-main-class-name.gradle")
+				.script("src/main/gradle/running/spring-boot-dsl-main-class-name"
+						+ this.dsl.getExtension())
 				.build("configuredMainClass").getOutput())
 						.contains("com.example.ExampleApplication");
 	}
@@ -62,7 +70,8 @@ public class RunningDocumentationTests {
 	@Test
 	public void bootRunSourceResources() throws IOException {
 		assertThat(this.gradleBuild
-				.script("src/main/gradle/running/boot-run-source-resources.gradle")
+				.script("src/main/gradle/running/boot-run-source-resources"
+						+ this.dsl.getExtension())
 				.build("configuredClasspath").getOutput())
 						.contains(new File("src/main/resources").getPath());
 	}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/testkit/GradleBuild.java

@@ -26,6 +26,7 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.regex.Pattern;
 
+import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.xpath.XPath;
 import javax.xml.xpath.XPathExpression;
 import javax.xml.xpath.XPathFactory;
@@ -43,6 +44,9 @@ import org.junit.rules.TemporaryFolder;
 import org.junit.rules.TestRule;
 import org.junit.runner.Description;
 import org.junit.runners.model.Statement;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.NodeList;
 import org.xml.sax.InputSource;
 
 import org.springframework.asm.ClassVisitor;
@@ -162,12 +166,19 @@ public class GradleBuild implements TestRule {
 
 	public GradleRunner prepareRunner(String... arguments) throws IOException {
 		String scriptContent = FileCopyUtils.copyToString(new FileReader(this.script))
-				.replace("{version}", getBootVersion());
+				.replace("{version}", getBootVersion())
+				.replace("{dependency-management-plugin-version}",
+						getDependencyManagementPluginVersion());
+		boolean isKotlin = this.script.endsWith(".kts");
+		String extension = isKotlin ? ".kts" : "";
 		FileCopyUtils.copy(scriptContent,
-				new FileWriter(new File(this.projectDir, "build.gradle")));
+				new FileWriter(new File(this.projectDir, "build.gradle" + extension)));
 		GradleRunner gradleRunner = GradleRunner.create().withProjectDir(this.projectDir)
-				.withDebug(true).withPluginClasspath(pluginClasspath());
-
+				.withPluginClasspath(pluginClasspath());
+		if (!isKotlin) {
+			// see https://github.com/gradle/gradle/issues/6862
+			gradleRunner.withDebug(true);
+		}
 		if (this.gradleVersion != null) {
 			gradleRunner.withGradleVersion(this.gradleVersion);
 		}
@@ -191,6 +202,11 @@ public class GradleBuild implements TestRule {
 		return this;
 	}
 
+	public GradleBuild withMinimalGradleVersionForKotlinDSL() {
+		this.gradleVersion = "4.10.2";
+		return this;
+	}
+
 	public String getGradleVersion() {
 		return this.gradleVersion;
 	}
@@ -201,13 +217,34 @@ public class GradleBuild implements TestRule {
 						+ "/text()");
 	}
 
+	private static String getDependencyManagementPluginVersion() {
+		try (FileReader pomReader = new FileReader(".flattened-pom.xml")) {
+			Document pom = DocumentBuilderFactory.newInstance().newDocumentBuilder()
+					.parse(new InputSource(pomReader));
+			NodeList dependencyElements = pom.getElementsByTagName("dependency");
+			for (int i = 0; i < dependencyElements.getLength(); i++) {
+				Element dependency = (Element) dependencyElements.item(i);
+				if (dependency.getElementsByTagName("artifactId").item(0).getTextContent()
+						.equals("dependency-management-plugin")) {
+					return dependency.getElementsByTagName("version").item(0)
+							.getTextContent();
+				}
+			}
+			throw new IllegalStateException(
+					"dependency management plugin version not found");
+		}
+		catch (Exception ex) {
+			throw new IllegalStateException(
+					"Failed to find dependency management plugin version", ex);
+		}
+	}
+
 	private static String evaluateExpression(String expression) {
-		try {
+		try (FileReader pomReader = new FileReader(".flattened-pom.xml")) {
 			XPathFactory xPathFactory = XPathFactory.newInstance();
 			XPath xpath = xPathFactory.newXPath();
 			XPathExpression expr = xpath.compile(expression);
-			String version = expr
-					.evaluate(new InputSource(new FileReader(".flattened-pom.xml")));
+			String version = expr.evaluate(new InputSource(pomReader));
 			return version;
 		}
 		catch (Exception ex) {