Format diff task

changelog/@unreleased/pr-988.v2.yml

@@ -0,0 +1,7 @@
+type: improvement
+improvement:
+  description: Run `./gradlew formatDiff -Pcom.palantir.baseline-format.palantir-java-format`
+    to reformat the relevant sections of any uncommitted changed Java files (relies
+    on `git diff -U0 HEAD` under the hood)
+  links:
+  - https://github.com/palantir/gradle-baseline/pull/988

gradle-baseline-java/src/main/groovy/com/palantir/baseline/plugins/BaselineFormat.java

@@ -18,18 +18,22 @@
 
 import com.diffplug.gradle.spotless.SpotlessExtension;
 import com.diffplug.spotless.FormatterFunc;
+import com.palantir.javaformat.java.FormatDiff;
 import com.palantir.javaformat.java.Formatter;
 import com.palantir.javaformat.java.JavaFormatterOptions;
 import com.palantir.javaformat.java.JavaFormatterOptions.Style;
 import java.io.File;
+import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import org.gradle.api.DefaultTask;
 import org.gradle.api.GradleException;
 import org.gradle.api.Project;
 import org.gradle.api.Task;
 import org.gradle.api.file.ConfigurableFileCollection;
 import org.gradle.api.plugins.JavaBasePlugin;
 import org.gradle.api.plugins.JavaPluginConvention;
+import org.gradle.api.tasks.TaskAction;
 import org.gradle.api.tasks.TaskProvider;
 import org.gradle.api.tasks.compile.JavaCompile;
 
@@ -45,6 +49,12 @@ public void apply(Project project) {
         this.project = project;
 
         project.getPluginManager().withPlugin("java", plugin -> {
+            project.getTasks().register("formatDiff", FormatDiffTask.class, task -> {
+                task.setDescription("Format only chunks of files that appear in git diff");
+                task.setGroup("Formatting");
+                task.onlyIf(t -> palantirJavaFormatterEnabled(project));
+            });
+
             project.getPluginManager().apply("com.diffplug.gradle.spotless");
             Path eclipseXml = eclipseConfigFile(project);
 
@@ -87,7 +97,9 @@ public void apply(Project project) {
             spotlessExtension.setEnforceCheck(false);
 
             // necessary because SpotlessPlugin creates tasks in an afterEvaluate block
-            TaskProvider<Task> formatTask = project.getTasks().register("format");
+            TaskProvider<Task> formatTask = project.getTasks().register("format", task -> {
+                task.setGroup("Formatting");
+            });
             project.afterEvaluate(p -> {
                 Task spotlessJava = project.getTasks().getByName("spotlessJava");
                 Task spotlessApply = project.getTasks().getByName("spotlessApply");
@@ -107,6 +119,13 @@ public void apply(Project project) {
         });
     }
 
+    public static class FormatDiffTask extends DefaultTask {
+        @TaskAction
+        public final void formatDiff() throws IOException, InterruptedException {
+            FormatDiff.formatDiff(getProject().getProjectDir().toPath());
+        }
+    }
+
     static boolean eclipseFormattingEnabled(Project project) {
         return project.hasProperty(ECLIPSE_FORMATTING);
     }

gradle-baseline-java/src/test/groovy/com/palantir/baseline/BaselineFormatIntegrationTest.groovy

@@ -221,4 +221,41 @@ class BaselineFormatIntegrationTest extends AbstractPluginTest {
         BuildResult result = with('spotlessJavaCheck').build()
         result.task(":spotlessJava").outcome == TaskOutcome.SUCCESS
     }
+
+    def 'formatDiff updates only lines changed in git diff'() {
+        when:
+        buildFile << standardBuildFile
+        "git init".execute(Collections.emptyList(), projectDir).waitFor()
+        "git config user.name Foo".execute(Collections.emptyList(), projectDir).waitFor()
+        "git config user.email foo@bar.com".execute(Collections.emptyList(), projectDir).waitFor()
+
+        file('src/main/java/Main.java') << '''
+        class Main {
+            public static void crazyExistingFormatting  (  String... args) {
+
+            }
+        }
+        '''.stripIndent()
+
+        "git add .".execute(Collections.emptyList(), projectDir).waitFor()
+        "git commit -m Commit".execute(Collections.emptyList(), projectDir).waitFor()
+
+        file('src/main/java/Main.java').text = '''
+        class Main {
+            public static void crazyExistingFormatting  (  String... args) {
+                                        System.out.println("Reformat me please");
+            }
+        }
+        '''.stripIndent()
+
+        then:
+        with('formatDiff', '-Pcom.palantir.baseline-format.palantir-java-format').build()
+        file('src/main/java/Main.java').text == '''
+        class Main {
+            public static void crazyExistingFormatting  (  String... args) {
+                System.out.println("Reformat me please");
+            }
+        }
+        '''.stripIndent()
+    }
 }

versions.props

@@ -7,7 +7,7 @@ com.google.errorprone:error_prone_test_helpers = 2.3.3
 com.google.guava:guava = 27.1-jre
 com.netflix.nebula:nebula-dependency-recommender = 9.0.0
 com.palantir.configurationresolver:gradle-configuration-resolver-plugin = 0.4.0
-com.palantir.javaformat:* = 0.2.7
+com.palantir.javaformat:* = 0.2.8
 com.palantir.safe-logging:* = 1.11.0
 org.apache.maven.shared:maven-dependency-analyzer = 1.11.1
 org.github.ngbinh.scalastyle:gradle-scalastyle-plugin_2.11 = 1.0.1