fix: expand a directory passed to targetExclude into the files under it

plugin-gradle/CHANGES.md

@@ -6,6 +6,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ### Fixed
 - `prettier()` and other npm-based steps no longer fail to start on npm 12 (`EUNKNOWNCONFIG` from `--scripts-prepend-node-path`). ([#3024](https://github.com/diffplug/spotless/issues/3024))
 - `spotlessInternalRegisterDependencies` now writes its output under a build directory that is configured after the plugin is applied, instead of always under the default `build/`. ([#2114](https://github.com/diffplug/spotless/issues/2114))
+- `targetExclude` now accepts a Gradle `Directory`, `DirectoryProperty`, or `Provider<Directory>` and excludes the files under it. Previously the directory was treated as a single file, so excluding one silently did nothing. ([#2667](https://github.com/diffplug/spotless/issues/2667))
 
 ## [8.10.0] - 2026-08-17
 ### Added

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/FormatExtension.java

@@ -47,7 +47,9 @@
 import org.gradle.api.file.ConfigurableFileTree;
 import org.gradle.api.file.Directory;
 import org.gradle.api.file.FileCollection;
+import org.gradle.api.file.FileSystemLocation;
 import org.gradle.api.plugins.BasePlugin;
+import org.gradle.api.provider.Provider;
 import org.gradle.api.tasks.TaskProvider;
 import org.gradle.util.GradleVersion;
 import org.slf4j.Logger;
@@ -344,6 +346,9 @@ private final FileCollection parseTargetIsExclude(Object target, boolean isExclu
 				matchedFiles.exclude(excludes);
 			}
 			return matchedFiles;
+		} else if (isExclude && (target instanceof FileSystemLocation || target instanceof Provider)) {
+			// an excluded directory means the files under it, and the tree resolves them lazily
+			return getProject().files(target).getAsFileTree();
 		} else {
 			return getProject().files(target);
 		}

plugin-gradle/src/test/java/com/diffplug/gradle/spotless/TargetExcludeDirectoryTest.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright 2026 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.gradle.spotless;
+
+import java.io.IOException;
+
+import org.junit.jupiter.api.Test;
+
+class TargetExcludeDirectoryTest extends GradleIntegrationHarness {
+	@Test
+	void targetExcludeWithDirectory() throws IOException {
+		setFile("build.gradle").toLines(
+				"plugins { id 'com.diffplug.spotless' }",
+				"spotless {",
+				"  format 'toLower', {",
+				"    target '**/*.md'",
+				"    targetExclude layout.projectDirectory.dir('generated')",
+				"    custom 'lowercase', { str -> str.toLowerCase() }",
+				"  }",
+				"}");
+		setFile("generated/excluded.md").toLines("A B C");
+		setFile("generated/nested/excluded.md").toLines("A B C");
+		setFile("manual.md").toLines("A B C");
+
+		gradleRunner().withArguments("spotlessApply").build();
+
+		assertFile("generated/excluded.md").hasLines("A B C");
+		assertFile("generated/nested/excluded.md").hasLines("A B C");
+		assertFile("manual.md").hasLines("a b c");
+	}
+
+	@Test
+	void targetExcludeWithDirectoryProperty() throws IOException {
+		setFile("build.gradle").toLines(
+				"plugins { id 'com.diffplug.spotless' }",
+				"def excluded = objects.directoryProperty()",
+				"excluded.set(layout.projectDirectory.dir('generated'))",
+				"spotless {",
+				"  format 'toLower', {",
+				"    target '**/*.md'",
+				"    targetExclude excluded",
+				"    custom 'lowercase', { str -> str.toLowerCase() }",
+				"  }",
+				"}");
+		setFile("generated/excluded.md").toLines("A B C");
+		setFile("manual.md").toLines("A B C");
+
+		gradleRunner().withArguments("spotlessApply").build();
+
+		assertFile("generated/excluded.md").hasLines("A B C");
+		assertFile("manual.md").hasLines("a b c");
+	}
+
+	@Test
+	void targetExcludeWithDirectoryProvider() throws IOException {
+		setFile("build.gradle").toLines(
+				"plugins { id 'com.diffplug.spotless' }",
+				"spotless {",
+				"  format 'toLower', {",
+				"    target '**/*.md'",
+				"    targetExclude providers.provider { layout.projectDirectory.dir('generated') }",
+				"    custom 'lowercase', { str -> str.toLowerCase() }",
+				"  }",
+				"}");
+		setFile("generated/excluded.md").toLines("A B C");
+		setFile("manual.md").toLines("A B C");
+
+		gradleRunner().withArguments("spotlessApply").build();
+
+		assertFile("generated/excluded.md").hasLines("A B C");
+		assertFile("manual.md").hasLines("a b c");
+	}
+
+	@Test
+	void targetExcludeWithDirectoryAndConfigurationCache() throws IOException {
+		setFile("gradle.properties").toLines("org.gradle.configuration-cache=true");
+		setFile("build.gradle").toLines(
+				"plugins { id 'com.diffplug.spotless' }",
+				"spotless {",
+				"  format 'toLower', {",
+				"    target '**/*.md'",
+				"    targetExclude layout.projectDirectory.dir('generated')",
+				"    custom 'lowercase', { str -> str.toLowerCase() }",
+				"  }",
+				"}");
+		setFile("generated/excluded.md").toLines("A B C");
+		setFile("manual.md").toLines("A B C");
+
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("generated/excluded.md").hasLines("A B C");
+		assertFile("manual.md").hasLines("a b c");
+
+		// the exclusion still applies on a second run with the cache enabled
+		setFile("manual.md").toLines("D E F");
+		gradleRunner().withArguments("spotlessApply").build();
+		assertFile("generated/excluded.md").hasLines("A B C");
+		assertFile("manual.md").hasLines("d e f");
+	}
+
+}