Kotlin support in Maven plugin

plugin-maven/src/main/java/com/diffplug/spotless/maven/AbstractSpotlessMojo.java

@@ -42,6 +42,7 @@
 import com.diffplug.spotless.maven.generic.Format;
 import com.diffplug.spotless.maven.generic.LicenseHeader;
 import com.diffplug.spotless.maven.java.Java;
+import com.diffplug.spotless.maven.kotlin.Kotlin;
 import com.diffplug.spotless.maven.scala.Scala;
 
 public abstract class AbstractSpotlessMojo extends AbstractMojo {
@@ -85,6 +86,9 @@ public abstract class AbstractSpotlessMojo extends AbstractMojo {
 	@Parameter
 	private Scala scala;
 
+	@Parameter
+	private Kotlin kotlin;
+
 	protected abstract void process(List<File> files, Formatter formatter) throws MojoExecutionException;
 
 	@Override
@@ -142,7 +146,7 @@ private FileLocator getFileLocator() {
 	}
 
 	private List<FormatterFactory> getFormatterFactories() {
-		return Stream.of(format, java, scala)
+		return Stream.of(format, java, scala, kotlin)
 				.filter(Objects::nonNull)
 				.collect(toList());
 	}

plugin-maven/src/main/java/com/diffplug/spotless/maven/kotlin/Kotlin.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2016 DiffPlug
+ *
+ * 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 com.diffplug.spotless.maven.kotlin;
+
+import static com.diffplug.common.collect.Sets.newHashSet;
+import static java.util.Collections.unmodifiableSet;
+
+import java.util.Set;
+
+import com.diffplug.spotless.maven.FormatterFactory;
+
+public class Kotlin extends FormatterFactory {
+
+	private static final Set<String> DEFAULT_INCLUDES = unmodifiableSet(newHashSet("src/main/kotlin/**/*.kt",
+			"src/test/kotlin/**/*.kt"));
+
+	private static final String LICENSE_HEADER_DELIMITER = "(package |@file)";
+
+	@Override
+	public Set<String> defaultIncludes() {
+		return DEFAULT_INCLUDES;
+	}
+
+	@Override
+	public String licenseHeaderDelimiter() {
+		return LICENSE_HEADER_DELIMITER;
+	}
+
+	public void addKtlint(Ktlint ktlint) {
+		addStepFactory(ktlint);
+	}
+}

plugin-maven/src/main/java/com/diffplug/spotless/maven/kotlin/Ktlint.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2016 DiffPlug
+ *
+ * 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 com.diffplug.spotless.maven.kotlin;
+
+import org.apache.maven.plugins.annotations.Parameter;
+
+import com.diffplug.spotless.FormatterStep;
+import com.diffplug.spotless.kotlin.KtLintStep;
+import com.diffplug.spotless.maven.FormatterStepConfig;
+import com.diffplug.spotless.maven.FormatterStepFactory;
+
+public class Ktlint implements FormatterStepFactory {
+
+	@Parameter
+	private String version;
+
+	@Override
+	public FormatterStep newFormatterStep(FormatterStepConfig config) {
+		String ktlintVersion = version != null ? version : KtLintStep.defaultVersion();
+		return KtLintStep.create(ktlintVersion, config.getProvisioner());
+	}
+}

plugin-maven/src/test/java/com/diffplug/spotless/maven/MavenIntegrationTest.java

@@ -98,6 +98,10 @@ protected void writePomWithScalaSteps(String... steps) throws IOException {
 		writePom(groupWithSteps("scala", steps));
 	}
 
+	protected void writePomWithKotlinSteps(String... steps) throws IOException {
+		writePom(groupWithSteps("kotlin", steps));
+	}
+
 	protected void writePom(String... configuration) throws IOException {
 		writePom(null, configuration);
 	}

plugin-maven/src/test/java/com/diffplug/spotless/maven/generic/LicenseHeaderTest.java

@@ -21,6 +21,7 @@
 
 public class LicenseHeaderTest extends MavenIntegrationTest {
 	private static final String KEY_LICENSE = "license/TestLicense";
+	private static final String KOTLIN_LICENSE_HEADER = "// Hello, I'm Kotlin license header";
 
 	@Test
 	public void fromFileJava() throws Exception {
@@ -79,6 +80,23 @@ public void fromContentFormat() throws Exception {
 		runTest();
 	}
 
+	@Test
+	public void fromContentKotlin() throws Exception {
+		writePomWithKotlinSteps(
+				"<licenseHeader>",
+				"  <content>",
+				KOTLIN_LICENSE_HEADER,
+				"  </content>",
+				"</licenseHeader>");
+
+		String path = "src/main/kotlin/test.kt";
+		String noLicenseHeader = getTestResource("kotlin/licenseheader/KotlinCodeWithoutHeader.test");
+
+		setFile(path).toContent(noLicenseHeader);
+		mavenRunner().withArguments("spotless:apply").runNoError();
+		assertFile(path).hasContent(KOTLIN_LICENSE_HEADER + '\n' + noLicenseHeader);
+	}
+
 	private void runTest() throws Exception {
 		String path = "src/main/java/test.java";
 		setFile(path).toResource("license/MissingLicense.test");

plugin-maven/src/test/java/com/diffplug/spotless/maven/kotlin/KtLintTest.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2016 DiffPlug
+ *
+ * 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 com.diffplug.spotless.maven.kotlin;
+
+import org.junit.Test;
+
+import com.diffplug.spotless.maven.MavenIntegrationTest;
+
+public class KtLintTest extends MavenIntegrationTest {
+
+	@Test
+	public void testKtlint() throws Exception {
+		writePomWithKotlinSteps("<ktlint/>");
+
+		String path1 = "src/main/kotlin/main1.kt";
+		String path2 = "src/main/kotlin/main2.kt";
+
+		setFile(path1).toResource("kotlin/ktlint/basic.dirty");
+		setFile(path2).toResource("kotlin/ktlint/basic.dirty");
+
+		mavenRunner().withArguments("spotless:apply").runNoError();
+
+		assertFile(path1).sameAsResource("kotlin/ktlint/basic.clean");
+		assertFile(path2).sameAsResource("kotlin/ktlint/basic.clean");
+	}
+}