Format diff task

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

@@ -0,0 +1,7 @@
+type: improvement
+improvement:
+  description: >
+    Run `./gradlew formatDiff` 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/Baseline.java

@@ -36,10 +36,6 @@ public void apply(Project project) {
 
         rootProject.getPluginManager().apply(BaselineConfig.class);
         rootProject.getPluginManager().apply(BaselineCircleCi.class);
-        if (BaselineFormat.palantirJavaFormatterEnabled(project)) {
-            rootProject.getPluginManager().apply("com.palantir.java-format-provider");
-            rootProject.getPluginManager().apply("com.palantir.java-format-idea");
-        }
         rootProject.allprojects(proj -> {
             proj.getPluginManager().apply(BaselineCheckstyle.class);
             proj.getPluginManager().apply(BaselineScalastyle.class);

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

@@ -20,6 +20,9 @@
 import com.google.common.base.Preconditions;
 import com.palantir.baseline.plugins.format.PalantirJavaFormatStep;
 import com.palantir.javaformat.gradle.JavaFormatExtension;
+import com.palantir.javaformat.gradle.PalantirJavaFormatIdeaPlugin;
+import com.palantir.javaformat.gradle.PalantirJavaFormatPlugin;
+import com.palantir.javaformat.gradle.PalantirJavaFormatProviderPlugin;
 import java.io.File;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -43,6 +46,18 @@ class BaselineFormat extends AbstractBaselinePlugin {
     public void apply(Project project) {
         this.project = project;
 
+        if (project == project.getRootProject()) {
+            if (BaselineFormat.palantirJavaFormatterEnabled(project)) {
+                project.getPluginManager().apply(PalantirJavaFormatIdeaPlugin.class);
+            }
+        }
+
+        project.getPluginManager().withPlugin("java", plugin -> {
+            if (palantirJavaFormatterEnabled(project)) {
+                project.getPlugins().apply(PalantirJavaFormatPlugin.class); // provides the formatDiff task
+            }
+        });
+
         project.getPluginManager().withPlugin("java", plugin -> {
             project.getPluginManager().apply("com.diffplug.gradle.spotless");
             Path eclipseXml = eclipseConfigFile(project);
@@ -75,8 +90,8 @@ public void apply(Project project) {
 
                 if (palantirJavaFormatterEnabled(project)) {
                     Preconditions.checkState(
-                            project.getRootProject().getPluginManager().hasPlugin("com.palantir.java-format-provider"),
-                            "Must apply `com.palantir.baseline` to root project when setting '%s'",
+                            project.getRootProject().getPlugins().hasPlugin(PalantirJavaFormatProviderPlugin.class),
+                            "Must apply `com.palantir.baseline-format` to root project when setting '%s'",
                             PJF_PROPERTY);
                     java.addStep(PalantirJavaFormatStep.create(
                             project.getRootProject().getConfigurations().getByName("palantirJavaFormat"),
@@ -92,7 +107,9 @@ 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");

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

@@ -40,6 +40,11 @@ class BaselineFormatIntegrationTest extends AbstractPluginTest {
             id 'java'
             id 'com.palantir.baseline-format'
         }
+        repositories {
+            // to resolve the `palantirJavaFormat` configuration
+            maven { url 'https://dl.bintray.com/palantir/releases' }
+            jcenter()
+        }
     '''.stripIndent()
 
     def noJavaBuildFile = '''
@@ -227,4 +232,41 @@ 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()
+    }
 }