reinstall support

Author: lazer-dev

lib/src/main/java/com/diffplug/spotless/GitPrePushHookInstaller.java

@@ -100,23 +100,74 @@ public void install() throws Exception {
 		}
 
 		if (isGitHookInstalled(gitHookFile)) {
-			logger.warn("Skipping, git pre-push hook already installed %s", gitHookFile.getAbsolutePath());
-			return;
+			logger.info("Git pre-push hook already installed, reinstalling it");
+			uninstall(gitHookFile);
 		}
 
 		hookContent += preHookContent();
-		writeFile(gitHookFile, hookContent);
+		writeFile(gitHookFile, hookContent, true);
 
 		logger.info("Git pre-push hook installed successfully to the file %s", gitHookFile.getAbsolutePath());
 	}
 
+	/**
+	 * Uninstalls the Spotless Git pre-push hook from the specified hook file by removing
+	 * the custom hook content between the defined hook markers.
+	 *
+	 * <p>This method:
+	 * <ul>
+	 *   <li>Reads the entire content of the pre-push hook file</li>
+	 *   <li>Identifies the Spotless hook section using predefined markers</li>
+	 *   <li>Removes the Spotless hook content while preserving other hook content</li>
+	 *   <li>Writes the modified content back to the hook file</li>
+	 * </ul>
+	 *
+	 * @param gitHookFile The Git pre-push hook file from which to remove the Spotless hook
+	 * @throws Exception if any error occurs during the uninstallation process,
+	 *                  such as file reading or writing errors
+	 */
+	private void uninstall(File gitHookFile) throws Exception {
+		final var hook = Files.readString(gitHookFile.toPath(), UTF_8);
+		final var hookStart = hook.indexOf(HOOK_HEADLINE);
+		final var hookEnd = hook.indexOf(HOOK_FOOTER) + HOOK_FOOTER.length();
+
+		final var hookScript = hook.substring(hookStart, hookEnd);
+
+		final var uninstalledHook = hook.replace(hookScript, "");
+
+		writeFile(gitHookFile, uninstalledHook, false);
+	}
+
 	/**
 	 * Provides the content of the hook that should be inserted into the pre-push script.
 	 *
 	 * @return A string representing the content to include in the pre-push script.
 	 */
 	protected abstract String preHookContent();
 
+	/**
+	 * Generates a pre-push template script that defines the commands to check and apply changes
+	 * using an executor and Spotless.
+	 *
+	 * @param executor      The tool to execute the check and apply commands.
+	 * @param commandCheck  The command to check for issues.
+	 * @param commandApply  The command to apply corrections.
+	 * @return A string template representing the Spotless Git pre-push hook content.
+	 */
+	protected String preHookTemplate(String executor, String commandCheck, String commandApply) {
+		var spotlessHook = "\n";
+		spotlessHook += "\n" + HOOK_HEADLINE;
+		spotlessHook += "\nSPOTLESS_EXECUTOR=" + executor;
+		spotlessHook += "\nif ! $SPOTLESS_EXECUTOR " + commandCheck + " ; then";
+		spotlessHook += "\n    echo 1>&2 \"spotless found problems, running " + commandApply + "; commit the result and re-push\"";
+		spotlessHook += "\n    $SPOTLESS_EXECUTOR " + commandApply;
+		spotlessHook += "\n    exit 1";
+		spotlessHook += "\nfi";
+		spotlessHook += "\n" + HOOK_FOOTER;
+		spotlessHook += "\n";
+		return spotlessHook;
+	}
+
 	/**
 	 * Checks if Git is installed by validating the existence of `.git/config` in the repository root.
 	 *
@@ -145,38 +196,17 @@ private boolean isGitHookInstalled(File gitHookFile) throws Exception {
 	 * @param content The content to write into the file.
 	 * @throws IOException if an error occurs while writing to the file.
 	 */
-	private void writeFile(File file, String content) throws IOException {
-		try (final var writer = new FileWriter(file, UTF_8, true)) {
+	private void writeFile(File file, String content, boolean append) throws IOException {
+		try (final var writer = new FileWriter(file, UTF_8, append)) {
 			writer.write(content);
 		}
 	}
 
-	/**
-	 * Generates a pre-push template script that defines the commands to check and apply changes
-	 * using an executor and Spotless.
-	 *
-	 * @param executor      The tool to execute the check and apply commands.
-	 * @param commandCheck  The command to check for issues.
-	 * @param commandApply  The command to apply corrections.
-	 * @return A string template representing the Spotless Git pre-push hook content.
-	 */
-	protected String preHookTemplate(String executor, String commandCheck, String commandApply) {
-		var spotlessHook = "\n";
-		spotlessHook += "\n" + HOOK_HEADLINE;
-		spotlessHook += "\nSPOTLESS_EXECUTOR=" + executor;
-		spotlessHook += "\nif ! $SPOTLESS_EXECUTOR " + commandCheck + " ; then";
-		spotlessHook += "\n    echo 1>&2 \"spotless found problems, running " + commandApply + "; commit the result and re-push\"";
-		spotlessHook += "\n    $SPOTLESS_EXECUTOR " + commandApply;
-		spotlessHook += "\n    exit 1";
-		spotlessHook += "\nfi";
-		spotlessHook += "\n" + HOOK_FOOTER;
-		spotlessHook += "\n\n";
-		return spotlessHook;
-	}
-
 	public interface GitPreHookLogger {
 		void info(String format, Object... arguments);
+
 		void warn(String format, Object... arguments);
+
 		void error(String format, Object... arguments);
 	}
 }

lib/src/main/java/com/diffplug/spotless/GitPrePushHookInstallerGradle.java

@@ -33,7 +33,6 @@ public GitPrePushHookInstallerGradle(GitPreHookLogger logger, File root) {
 		this.gradlew = root.toPath().resolve("gradlew").toFile();
 	}
 
-
 	/**
 	 * {@inheritDoc}
 	 */

plugin-gradle/README.md

@@ -53,7 +53,7 @@ Spotless supports all of Gradle's built-in performance features (incremental bui
 
 - [**Quickstart**](#quickstart)
   - [Requirements](#requirements)
-  - [Git hook](#git-hook)
+  - [Git pre-push hook](#git-pre-push-hook)
   - [Linting](#linting)
 - **Languages**
   - [Java](#java) ([google-java-format](#google-java-format), [eclipse jdt](#eclipse-jdt), [clang-format](#clang-format), [prettier](#prettier), [palantir-java-format](#palantir-java-format), [formatAnnotations](#formatAnnotations), [cleanthat](#cleanthat), [IntelliJ IDEA](#intellij-idea))
@@ -142,9 +142,34 @@ Spotless requires JRE 11+ and Gradle 6.1.1 or newer.
 - If you're stuck on JRE 8, use [`id 'com.diffplug.spotless' version '6.13.0'` or older](https://github.com/diffplug/spotless/blob/main/plugin-gradle/CHANGES.md#6130---2023-01-14).
 - If you're stuck on an older version of Gradle, [`id 'com.diffplug.gradle.spotless' version '4.5.1'` supports all the way back to Gradle 2.x](https://github.com/diffplug/spotless/blob/main/plugin-gradle/CHANGES.md#451---2020-07-04).
 
-### Git hook
+### Git pre-push hook
 
-TODO
+You can install a Git pre-push hook that ensures code is properly formatted before being pushed to a remote repository.
+This helps catch formatting issues early — before CI fails — and is especially useful for teams not using IDE integrations or pre-commit tools.
+
+#### What the hook does
+
+When installed, the Git `pre-push` hook will:
+
+1. Run `spotlessCheck`
+2. If formatting issues are found:
+   - It automatically runs `spotlessApply` to fix them
+   - Aborts the push with a message
+   - You can then commit the changes and push again
+
+This ensures your code is always clean before it leaves your machine.
+
+#### Installation
+
+Run the following task once in your project:
+```console
+gradle spotlessInstallGitPrePushHook
+```
+
+This installs a `.git/hooks/pre-push` script that runs `spotlessCheck`, and runs `spotlessApply` if needed.
+
+> [!WARNING]
+> The hook will not install automatically — you must run the install command manually.
 
 ### Linting
 

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

@@ -44,7 +44,7 @@ public void should_create_pre_hook_file_when_hook_file_does_not_exists() throws
 		assertThat(output).contains("Git pre-push hook not found, creating it");
 		assertThat(output).contains("Git pre-push hook installed successfully to the file " + newFile(".git/hooks/pre-push"));
 
-		final var content = getTestResource("git_pre_hook/pre-push.created")
+		final var content = getTestResource("git_pre_hook/pre-push.created-tpl")
 				.replace("${executor}", "gradle")
 				.replace("${checkCommand}", "spotlessCheck")
 				.replace("${applyCommand}", "spotlessApply");
@@ -73,7 +73,7 @@ public void should_append_to_existing_pre_hook_file_when_hook_file_exists() thro
 		assertThat(output).contains("Installing git pre-push hook");
 		assertThat(output).contains("Git pre-push hook installed successfully to the file " + newFile(".git/hooks/pre-push"));
 
-		final var content = getTestResource("git_pre_hook/pre-push.existing-added")
+		final var content = getTestResource("git_pre_hook/pre-push.existing-added-tpl")
 				.replace("${executor}", "gradle")
 				.replace("${checkCommand}", "spotlessCheck")
 				.replace("${applyCommand}", "spotlessApply");

plugin-maven/README.md

@@ -37,7 +37,7 @@ user@machine repo % mvn spotless:check
 
 - [**Quickstart**](#quickstart)
   - [Requirements](#requirements)
-  - [Git hook](#git-hook)
+  - [Git pre-push hook](#git-pre-push-hook)
   - [Binding to maven phase](#binding-to-maven-phase)
 - **Languages**
   - [Java](#java) ([google-java-format](#google-java-format), [eclipse jdt](#eclipse-jdt), [prettier](#prettier), [palantir-java-format](#palantir-java-format), [formatAnnotations](#formatAnnotations), [cleanthat](#cleanthat), [IntelliJ IDEA](#intellij-idea))
@@ -147,9 +147,34 @@ Spotless consists of a list of formats (in the example above, `misc` and `java`)
 Spotless requires Maven to be running on JRE 11+. To use JRE 8, go back to [`2.30.0` or older](https://github.com/diffplug/spotless/blob/main/plugin-maven/CHANGES.md#2300---2023-01-13).
 
 
-### Git hook
+### Git pre-push hook
 
-TODO
+You can install a Git pre-push hook that ensures code is properly formatted before being pushed to a remote repository.
+This helps catch formatting issues early — before CI fails — and is especially useful for teams not using IDE integrations or pre-commit tools.
+
+#### What the hook does
+
+When installed, the Git `pre-push` hook will:
+
+1. Run `spotless:check`
+2. If formatting issues are found:
+  - It automatically runs `spotless:apply` to fix them
+  - Aborts the push with a message
+  - You can then commit the changes and push again
+
+This ensures your code is always clean before it leaves your machine.
+
+#### Installation
+
+Run the following task once in your project:
+```console
+mvn spotless:install-git-pre-push-hook
+```
+
+This installs a `.git/hooks/pre-push` script that runs `spotless:check`, and runs `spotless:apply` if needed.
+
+> [!WARNING]
+> The hook will not install automatically — you must run the install command manually.
 
 ### Binding to maven phase
 

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

@@ -41,8 +41,8 @@ public void should_create_pre_hook_file_when_hook_file_does_not_exists() throws
 		assertThat(output).contains("Git pre-push hook not found, creating it");
 		assertThat(output).contains("Git pre-push hook installed successfully to the file " + newFile(".git/hooks/pre-push"));
 
-		final var content = getTestResource("git_pre_hook/pre-push.created")
-				.replace("${executor}", "mvn")
+		final var content = getTestResource("git_pre_hook/pre-push.created-tpl")
+				.replace("${executor}", newFile("mvnw").getAbsolutePath())
 				.replace("${checkCommand}", "spotless:check")
 				.replace("${applyCommand}", "spotless:apply");
 		assertFile(".git/hooks/pre-push").hasContent(content);
@@ -67,8 +67,8 @@ public void should_append_to_existing_pre_hook_file_when_hook_file_exists() thro
 		assertThat(output).contains("Installing git pre-push hook");
 		assertThat(output).contains("Git pre-push hook installed successfully to the file " + newFile(".git/hooks/pre-push"));
 
-		final var content = getTestResource("git_pre_hook/pre-push.existing-added")
-				.replace("${executor}", "mvn")
+		final var content = getTestResource("git_pre_hook/pre-push.existing-added-tpl")
+				.replace("${executor}", newFile("mvnw").getAbsolutePath())
 				.replace("${checkCommand}", "spotless:check")
 				.replace("${applyCommand}", "spotless:apply");
 		assertFile(".git/hooks/pre-push").hasContent(content);

testlib/src/main/resources/git_pre_hook/pre-push.created renamed to testlib/src/main/resources/git_pre_hook/pre-push.created-tpl

@@ -9,4 +9,3 @@ if ! $SPOTLESS_EXECUTOR ${checkCommand} ; then
     exit 1
 fi
 ##### SPOTLESS HOOK END #####
-

testlib/src/main/resources/git_pre_hook/pre-push.existing-added renamed to testlib/src/main/resources/git_pre_hook/pre-push.existing-added-tpl

@@ -59,4 +59,3 @@ if ! $SPOTLESS_EXECUTOR ${checkCommand} ; then
     exit 1
 fi
 ##### SPOTLESS HOOK END #####
-

testlib/src/main/resources/git_pre_hook/pre-push.reinstalled-tpl

@@ -0,0 +1,64 @@
+#!/bin/sh
+
+# An example hook script to verify what is about to be pushed.  Called by "git
+# push" after it has checked the remote status, but before anything has been
+# pushed.  If this script exits with a non-zero status nothing will be pushed.
+#
+# This hook is called with the following parameters:
+#
+# $1 -- Name of the remote to which the push is being done
+# $2 -- URL to which the push is being done
+#
+# If pushing without using a named remote those arguments will be equal.
+#
+# Information about the commits which are being pushed is supplied as lines to
+# the standard input in the form:
+#
+#   <local ref> <local oid> <remote ref> <remote oid>
+#
+# This sample shows how to prevent push of commits where the log message starts
+# with "WIP" (work in progress).
+
+remote="$1"
+url="$2"
+
+zero=$(git hash-object --stdin </dev/null | tr '[0-9a-f]' '0')
+
+while read local_ref local_oid remote_ref remote_oid
+do
+        if test "$local_oid" = "$zero"
+        then
+                # Handle delete
+                :
+        else
+                if test "$remote_oid" = "$zero"
+                then
+                        # New branch, examine all commits
+                        range="$local_oid"
+                else
+                        # Update to existing branch, examine new commits
+                        range="$remote_oid..$local_oid"
+                fi
+
+                # Check for WIP commit
+                commit=$(git rev-list -n 1 --grep '^WIP' "$range")
+                if test -n "$commit"
+                then
+                        echo >&2 "Found WIP commit in $local_ref, not pushing"
+                        exit 1
+                fi
+        fi
+done
+
+
+
+
+
+##### SPOTLESS HOOK START #####
+SPOTLESS_EXECUTOR=${executor}
+if ! $SPOTLESS_EXECUTOR ${checkCommand} ; then
+    echo 1>&2 "spotless found problems, running ${applyCommand}; commit the result and re-push"
+    $SPOTLESS_EXECUTOR ${applyCommand}
+    exit 1
+fi
+##### SPOTLESS HOOK END #####