Enable up-to-date checking in Maven plugin by default

plugin-maven/CHANGES.md

@@ -7,6 +7,8 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 * You can now put the filename into a license header template with `$FILE`. ([#1605](https://github.com/diffplug/spotless/pull/1605) fixes [#1147](https://github.com/diffplug/spotless/issues/1147))
 ### Fixed
 * `licenseHeader` default pattern for Java files is updated to `(package|import|public|class|module) `. ([#1614](https://github.com/diffplug/spotless/pull/1614))
+### Changes
+* Enable incremental up-to-date checking by default. ([#1621](https://github.com/diffplug/spotless/pull/1621))
 
 ## [2.34.0] - 2023-02-27
 ### Added

plugin-maven/README.md

@@ -1262,7 +1262,7 @@ To define what lines to skip at the beginning of such files, fill the `skipLines
 
 ## Incremental up-to-date checking and formatting
 
-**This feature is turned off by default.**
+**This feature is enabled by default starting from version 2.35.0.**
 
 Execution of `spotless:check` and `spotless:apply` for large projects can take time.
 By default, Spotless Maven plugin needs to read and format each source file.

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

@@ -187,7 +187,7 @@ public abstract class AbstractSpotlessMojo extends AbstractMojo {
 	private String setLicenseHeaderYearsFromGitHistory;
 
 	@Parameter
-	private UpToDateChecking upToDateChecking;
+	private UpToDateChecking upToDateChecking = UpToDateChecking.enabled();
 
 	protected abstract void process(Iterable<File> files, Formatter formatter, UpToDateChecker upToDateChecker) throws MojoExecutionException;
 
@@ -373,9 +373,9 @@ private UpToDateChecker createUpToDateChecker(Iterable<Formatter> formatters) {
 		}
 		final UpToDateChecker checker;
 		if (upToDateChecking != null && upToDateChecking.isEnabled()) {
-			getLog().info("Up-to-date checking enabled");
 			checker = UpToDateChecker.forProject(project, indexFile, formatters, getLog());
 		} else {
+			getLog().info("Up-to-date checking disabled");
 			checker = UpToDateChecker.noop(project, indexFile, getLog());
 		}
 		return UpToDateChecker.wrapWithBuildContext(checker, buildContext);

plugin-maven/src/main/java/com/diffplug/spotless/maven/incremental/PluginFingerprint.java

@@ -21,6 +21,7 @@
 import java.util.Objects;
 
 import org.apache.maven.model.Plugin;
+import org.apache.maven.model.PluginManagement;
 import org.apache.maven.project.MavenProject;
 
 import com.diffplug.spotless.Formatter;
@@ -43,10 +44,7 @@ private PluginFingerprint(String value) {
 	}
 
 	static PluginFingerprint from(MavenProject project, Iterable<Formatter> formatters) {
-		Plugin spotlessPlugin = project.getPlugin(SPOTLESS_PLUGIN_KEY);
-		if (spotlessPlugin == null) {
-			throw new IllegalArgumentException("Spotless plugin absent from the project: " + project);
-		}
+		Plugin spotlessPlugin = findSpotlessPlugin(project);
 		byte[] digest = digest(spotlessPlugin, formatters);
 		String value = Base64.getEncoder().encodeToString(digest);
 		return new PluginFingerprint(value);
@@ -86,6 +84,24 @@ public String toString() {
 		return "PluginFingerprint[" + value + "]";
 	}
 
+	private static Plugin findSpotlessPlugin(MavenProject project) {
+		// Try to find the plugin instance from <build><plugins><plugin> XML element
+		Plugin plugin = project.getPlugin(SPOTLESS_PLUGIN_KEY);
+		if (plugin == null) {
+			// Try to find the plugin instance from <build><pluginManagement><plugins><plugin> XML element. Useful when
+			// the current module is a parent of a multimodule project
+			PluginManagement pluginManagement = project.getPluginManagement();
+			if (pluginManagement != null) {
+				plugin = pluginManagement.getPluginsAsMap().get(SPOTLESS_PLUGIN_KEY);
+			}
+		}
+
+		if (plugin == null) {
+			throw new IllegalArgumentException("Spotless plugin absent from the project: " + project);
+		}
+		return plugin;
+	}
+
 	private static byte[] digest(Plugin plugin, Iterable<Formatter> formatters) {
 		try (ObjectDigestOutputStream out = ObjectDigestOutputStream.create()) {
 			out.writeObject(plugin.getVersion());

plugin-maven/src/main/java/com/diffplug/spotless/maven/incremental/UpToDateChecking.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021-2022 DiffPlug
+ * Copyright 2021-2023 DiffPlug
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -38,4 +38,10 @@ public boolean isEnabled() {
 	public Path getIndexFile() {
 		return indexFile == null ? null : new File(indexFile).toPath();
 	}
+
+	public static UpToDateChecking enabled() {
+		UpToDateChecking upToDateChecking = new UpToDateChecking();
+		upToDateChecking.enabled = true;
+		return upToDateChecking;
+	}
 }

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

@@ -32,31 +32,31 @@ class MultiModuleProjectTest extends MavenIntegrationHarness {
 	@Test
 	void testConfigurationDependency() throws Exception {
 		/*
-		create a multi-module project with the following stucture:
+		create a multi-module project with the following structure:
 
 		    /junit-tmp-dir
 		    ├── config
-		    │   ├── pom.xml
-		    │   └── src/main/resources/configs
-		    │       ├── eclipse-formatter.xml
-		    │       └── scalafmt.conf
+		    │   ├── pom.xml
+		    │   └── src/main/resources/configs
+		    │       ├── eclipse-formatter.xml
+		    │       └── scalafmt.conf
 		    ├── mvnw
 		    ├── mvnw.cmd
 		    ├── one
-		    │   ├── pom.xml
-		    │   └── src
-		    │       ├── main/java/test1.java
-		    │       └── test/java/test2.java
+		    │   ├── pom.xml
+		    │   └── src
+		    │       ├── main/java/test1.java
+		    │       └── test/java/test2.java
 		    ├── two
-		    │   ├── pom.xml
-		    │   └── src
-		    │       ├── main/java/test1.java
-		    │       └── test/java/test2.java
+		    │   ├── pom.xml
+		    │   └── src
+		    │       ├── main/java/test1.java
+		    │       └── test/java/test2.java
 		    ├── three
-		    │   ├── pom.xml
-		    │   └── src
-		    │       ├── main/scala/test1.scala
-		    │       └── test/scala/test2.scala
+		    │   ├── pom.xml
+		    │   └── src
+		    │       ├── main/scala/test1.scala
+		    │       └── test/scala/test2.scala
 		    ├── pom.xml
 		    ├── .mvn
 		    ├── mvnw

plugin-maven/src/test/java/com/diffplug/spotless/maven/incremental/PluginFingerprintTest.java

@@ -23,9 +23,12 @@
 import java.io.ByteArrayInputStream;
 import java.nio.file.Paths;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import org.apache.maven.model.Model;
+import org.apache.maven.model.Plugin;
+import org.apache.maven.model.PluginManagement;
 import org.apache.maven.model.io.xpp3.MavenXpp3Reader;
 import org.apache.maven.project.MavenProject;
 import org.codehaus.plexus.util.ReaderFactory;
@@ -106,14 +109,45 @@ void emptyFingerprint() {
 	}
 
 	@Test
-	void failsWhenProjectDoesNotContainSpotlessPlugin() {
+	void failsForProjectWithoutSpotlessPlugin() {
 		MavenProject projectWithoutSpotless = new MavenProject();
 
 		assertThatThrownBy(() -> PluginFingerprint.from(projectWithoutSpotless, FORMATTERS))
 				.isInstanceOf(IllegalArgumentException.class)
 				.hasMessageContaining("Spotless plugin absent from the project");
 	}
 
+	@Test
+	void buildsFingerprintForProjectWithSpotlessPluginInBuildPlugins() {
+		MavenProject project = new MavenProject();
+		Plugin spotlessPlugin = new Plugin();
+		spotlessPlugin.setGroupId("com.diffplug.spotless");
+		spotlessPlugin.setArtifactId("spotless-maven-plugin");
+		spotlessPlugin.setVersion("1.2.3");
+		project.getBuild().addPlugin(spotlessPlugin);
+
+		PluginFingerprint fingerprint = PluginFingerprint.from(project, Collections.emptyList());
+
+		assertThat(fingerprint).isNotNull();
+	}
+
+	@Test
+	void buildsFingerprintForProjectWithSpotlessPluginInPluginManagement() {
+		MavenProject project = new MavenProject();
+		Plugin spotlessPlugin = new Plugin();
+		spotlessPlugin.setGroupId("com.diffplug.spotless");
+		spotlessPlugin.setArtifactId("spotless-maven-plugin");
+		spotlessPlugin.setVersion("1.2.3");
+		project.getBuild().addPlugin(spotlessPlugin);
+		PluginManagement pluginManagement = new PluginManagement();
+		pluginManagement.addPlugin(spotlessPlugin);
+		project.getBuild().setPluginManagement(pluginManagement);
+
+		PluginFingerprint fingerprint = PluginFingerprint.from(project, Collections.emptyList());
+
+		assertThat(fingerprint).isNotNull();
+	}
+
 	private MavenProject mavenProject(String spotlessVersion) throws Exception {
 		String xml = createPomXmlContent(spotlessVersion, new String[0], new String[0]);
 		return new MavenProject(readPom(xml));

plugin-maven/src/test/java/com/diffplug/spotless/maven/incremental/UpToDateCheckingTest.java

@@ -31,8 +31,10 @@
 
 class UpToDateCheckingTest extends MavenIntegrationHarness {
 
+	private static final String DISABLED_MESSAGE = "Up-to-date checking disabled";
+
 	@Test
-	void upToDateCheckingDisabledByDefault() throws Exception {
+	void upToDateCheckingEnabledByDefault() throws Exception {
 		writePom(
 				"<java>",
 				"  <googleJavaFormat/>",
@@ -41,75 +43,53 @@ void upToDateCheckingDisabledByDefault() throws Exception {
 		List<File> files = writeUnformattedFiles(1);
 		String output = runSpotlessApply();
 
-		assertThat(output).doesNotContain("Up-to-date checking enabled");
+		assertThat(output).doesNotContain(DISABLED_MESSAGE);
 		assertFormatted(files);
 	}
 
 	@Test
-	void enableUpToDateChecking() throws Exception {
+	void explicitlyEnableUpToDateChecking() throws Exception {
 		writePomWithUpToDateCheckingEnabled(true);
 
 		List<File> files = writeUnformattedFiles(1);
 		String output = runSpotlessApply();
 
-		assertThat(output).contains("Up-to-date checking enabled");
+		assertThat(output).doesNotContain(DISABLED_MESSAGE);
 		assertFormatted(files);
 	}
 
 	@Test
-	void enableUpToDateCheckingWithPluginDependencies() throws Exception {
-		writePomWithPluginManagementAndDependency();
+	void explicitlyDisableUpToDateChecking() throws Exception {
+		writePomWithUpToDateCheckingEnabled(false);
 
 		List<File> files = writeUnformattedFiles(1);
 		String output = runSpotlessApply();
 
-		assertThat(output).contains("Up-to-date checking enabled");
+		assertThat(output).contains(DISABLED_MESSAGE);
 		assertFormatted(files);
 	}
 
 	@Test
-	void enableUpToDateCheckingWithPluginDependenciesMaven3_6_3() throws Exception {
+	void enableUpToDateCheckingWithPluginDependencies() throws Exception {
 		writePomWithPluginManagementAndDependency();
 
-		setFile(".mvn/wrapper/maven-wrapper.properties").toContent("distributionUrl=https://repo1.maven.org/maven2/org/apache/maven/apache-maven/3.6.3/apache-maven-3.6.3-bin.zip\n");
-
 		List<File> files = writeUnformattedFiles(1);
 		String output = runSpotlessApply();
 
-		assertThat(output).contains("Up-to-date checking enabled");
+		assertThat(output).doesNotContain(DISABLED_MESSAGE);
 		assertFormatted(files);
 	}
 
-	private void writePomWithPluginManagementAndDependency() throws IOException {
-		setFile("pom.xml").toContent(createPomXmlContent("/pom-test-management.xml.mustache",
-				null,
-				null,
-				new String[]{
-						"<java>",
-						"  <googleJavaFormat/>",
-						"</java>",
-						"<upToDateChecking>",
-						"  <enabled>true</enabled>",
-						"</upToDateChecking>"},
-				new String[]{
-						"<dependencies>",
-						"  <dependency>",
-						"    <groupId>javax.inject</groupId>",
-						"    <artifactId>javax.inject</artifactId>",
-						"    <version>1</version>",
-						"  </dependency>",
-						"</dependencies>"},
-				null));
-	}
-
 	@Test
-	void disableUpToDateChecking() throws Exception {
-		writePomWithUpToDateCheckingEnabled(false);
+	void enableUpToDateCheckingWithPluginDependenciesMaven3_6_3() throws Exception {
+		writePomWithPluginManagementAndDependency();
+
+		setFile(".mvn/wrapper/maven-wrapper.properties").toContent("distributionUrl=https://repo1.maven.org/maven2/org/apache/maven/apache-maven/3.6.3/apache-maven-3.6.3-bin.zip\n");
 
 		List<File> files = writeUnformattedFiles(1);
 		String output = runSpotlessApply();
 
-		assertThat(output).doesNotContain("Up-to-date checking enabled");
+		assertThat(output).doesNotContain(DISABLED_MESSAGE);
 		assertFormatted(files);
 	}
 
@@ -124,7 +104,7 @@ void enableUpToDateCheckingCustomIndexFile() throws Exception {
 		List<File> files = writeUnformattedFiles(1);
 		String output = runSpotlessApply();
 
-		assertThat(output).contains("Up-to-date checking enabled");
+		assertThat(output).doesNotContain(DISABLED_MESSAGE);
 		assertFormatted(files);
 		assertThat(indexFile.getParent()).exists();
 		assertThat(indexFile).exists();
@@ -143,7 +123,7 @@ void disableUpToDateCheckingCustomIndexFile() throws Exception {
 		List<File> files = writeUnformattedFiles(1);
 		String output = runSpotlessApply();
 
-		assertThat(output).doesNotContain("Up-to-date checking enabled");
+		assertThat(output).contains(DISABLED_MESSAGE);
 		assertFormatted(files);
 		assertThat(indexFile.getParent()).exists();
 		assertThat(indexFile).doesNotExist();
@@ -215,6 +195,25 @@ void spotlessCheckRecordsUnformattedFiles() throws Exception {
 		assertSpotlessCheckSkipped(files, checkOutput3);
 	}
 
+	private void writePomWithPluginManagementAndDependency() throws IOException {
+		setFile("pom.xml").toContent(createPomXmlContent("/pom-test-management.xml.mustache",
+				null,
+				null,
+				new String[]{
+						"<java>",
+						"  <googleJavaFormat/>",
+						"</java>"},
+				new String[]{
+						"<dependencies>",
+						"  <dependency>",
+						"    <groupId>javax.inject</groupId>",
+						"    <artifactId>javax.inject</artifactId>",
+						"    <version>1</version>",
+						"  </dependency>",
+						"</dependencies>"},
+				null));
+	}
+
 	private void writePomWithUpToDateCheckingEnabled(boolean enabled) throws IOException {
 		writePom(
 				"<java>",