Merge 45abae3e9f into 900f2210b1

* fix: expand merge commit SHA regex and add SHA-256 test cases

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* test: add checkCommitInfo SHA coverage

Add checkCommitInfo tests for SHA-1 and SHA-256 merge messages and reject invalid 50-character hex merge heads.\n\nCo-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* style: fix Prettier formatting in test and source files

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

README.md

@@ -112,6 +112,12 @@ Please refer to the [release page](https://github.com/actions/checkout/releases/
     # Default: true
     clean: ''
 
+    # Whether to preserve local changes during checkout. If true, tries to preserve
+    # local files that are not tracked by Git. By default, all files will be
+    # overwritten.
+    # Default: false
+    preserve-local-changes: ''
+
     # Partially clone against a given filter. Overrides sparse-checkout if set.
     # Default: null
     filter: ''
@@ -357,6 +363,21 @@ jobs:
 
 *NOTE:* The user email is `{user.id}+{user.login}@users.noreply.github.com`. See users API: https://api.github.com/users/github-actions%5Bbot%5D
 
+## Preserve local changes during checkout
+
+```yaml
+steps:
+  - name: Create file before checkout
+    shell: pwsh
+    run: New-Item -Path . -Name "example.txt" -ItemType "File"
+    
+  - name: Checkout with preserving local changes
+    uses: actions/checkout@v5
+    with:
+      clean: false
+      preserve-local-changes: true
+```
+
 # Recommended permissions
 
 When using the `checkout` action in your GitHub Actions workflow, it is recommended to set the following `GITHUB_TOKEN` permissions to ensure proper functionality, unless alternative auth is provided via the `token` or `ssh-key` inputs:

__test__/git-auth-helper.test.ts

@@ -1163,6 +1163,7 @@ async function setup(testName: string): Promise<void> {
     submodules: false,
     nestedSubmodules: false,
     persistCredentials: true,
+    preserveLocalChanges: false,
     ref: 'refs/heads/main',
     repositoryName: 'my-repo',
     repositoryOwner: 'my-org',

__test__/git-directory-helper.test.ts

@@ -143,12 +143,41 @@ describe('git-directory-helper tests', () => {
       repositoryPath,
       repositoryUrl,
       clean,
-      ref
+      ref,
+      false // preserveLocalChanges = false
     )
 
     // Assert
     const files = await fs.promises.readdir(repositoryPath)
-    expect(files).toHaveLength(0)
+    expect(files).toEqual(['.git']) // Expect just the .git directory to remain
+    expect(git.tryClean).toHaveBeenCalled()
+    expect(core.warning).toHaveBeenCalled()
+    expect(git.tryReset).not.toHaveBeenCalled()
+  })
+  
+  const preservesContentsWhenCleanFailsAndPreserveLocalChanges = 'preserves contents when clean fails and preserve-local-changes is true'
+  it(preservesContentsWhenCleanFailsAndPreserveLocalChanges, async () => {
+    // Arrange
+    await setup(preservesContentsWhenCleanFailsAndPreserveLocalChanges)
+    await fs.promises.writeFile(path.join(repositoryPath, 'my-file'), '')
+    let mockTryClean = git.tryClean as jest.Mock<any, any>
+    mockTryClean.mockImplementation(async () => {
+      return false
+    })
+
+    // Act
+    await gitDirectoryHelper.prepareExistingDirectory(
+      git,
+      repositoryPath,
+      repositoryUrl,
+      clean,
+      ref,
+      true // preserveLocalChanges = true
+    )
+
+    // Assert
+    const files = await fs.promises.readdir(repositoryPath)
+    expect(files.sort()).toEqual(['.git', 'my-file']) // Expect both .git and user files to remain
     expect(git.tryClean).toHaveBeenCalled()
     expect(core.warning).toHaveBeenCalled()
     expect(git.tryReset).not.toHaveBeenCalled()
@@ -170,16 +199,50 @@ describe('git-directory-helper tests', () => {
       repositoryPath,
       differentRepositoryUrl,
       clean,
-      ref
+      ref,
+      false // preserveLocalChanges = false
     )
 
     // Assert
     const files = await fs.promises.readdir(repositoryPath)
-    expect(files).toHaveLength(0)
+    expect(files).toEqual(['.git']) // Expect just the .git directory to remain
     expect(core.warning).not.toHaveBeenCalled()
     expect(git.isDetached).not.toHaveBeenCalled()
   })
 
+  const keepsContentsWhenDifferentRepositoryUrlAndPreserveLocalChanges =
+    'keeps contents when different repository url and preserve-local-changes is true'
+  it(keepsContentsWhenDifferentRepositoryUrlAndPreserveLocalChanges, async () => {
+    // Arrange
+    await setup(keepsContentsWhenDifferentRepositoryUrlAndPreserveLocalChanges)
+    clean = false
+    
+    // Create a file that we expect to be preserved
+    await fs.promises.writeFile(path.join(repositoryPath, 'my-file'), '')
+    
+    // Simulate a different repository by simply removing the .git directory
+    await io.rmRF(path.join(repositoryPath, '.git'))
+    await fs.promises.mkdir(path.join(repositoryPath, '.git'))
+    
+    const differentRepositoryUrl = 'https://github.com/my-different-org/my-different-repo'
+    
+    // Act
+    await gitDirectoryHelper.prepareExistingDirectory(
+      git,
+      repositoryPath,
+      differentRepositoryUrl, // Use a different URL
+      clean,
+      ref,
+      true // preserveLocalChanges = true
+    )
+
+    // Assert
+    const files = await fs.promises.readdir(repositoryPath)
+    console.log('Files after operation:', files)
+    // When preserveLocalChanges is true, files should be preserved even with different repo URL
+    expect(files.sort()).toEqual(['.git', 'my-file'].sort())
+  })
+
   const removesContentsWhenNoGitDirectory =
     'removes contents when no git directory'
   it(removesContentsWhenNoGitDirectory, async () => {
@@ -221,12 +284,41 @@ describe('git-directory-helper tests', () => {
       repositoryPath,
       repositoryUrl,
       clean,
-      ref
+      ref,
+      false // preserveLocalChanges = false
     )
 
     // Assert
     const files = await fs.promises.readdir(repositoryPath)
-    expect(files).toHaveLength(0)
+    expect(files).toEqual(['.git']) // Expect just the .git directory to remain
+    expect(git.tryClean).toHaveBeenCalled()
+    expect(git.tryReset).toHaveBeenCalled()
+    expect(core.warning).toHaveBeenCalled()
+  })
+
+  const preservesContentsWhenResetFailsAndPreserveLocalChanges = 'preserves contents when reset fails and preserve-local-changes is true'
+  it(preservesContentsWhenResetFailsAndPreserveLocalChanges, async () => {
+    // Arrange
+    await setup(preservesContentsWhenResetFailsAndPreserveLocalChanges)
+    await fs.promises.writeFile(path.join(repositoryPath, 'my-file'), '')
+    let mockTryReset = git.tryReset as jest.Mock<any, any>
+    mockTryReset.mockImplementation(async () => {
+      return false
+    })
+
+    // Act
+    await gitDirectoryHelper.prepareExistingDirectory(
+      git,
+      repositoryPath,
+      repositoryUrl,
+      clean,
+      ref,
+      true // preserveLocalChanges = true
+    )
+
+    // Assert
+    const files = await fs.promises.readdir(repositoryPath)
+    expect(files.sort()).toEqual(['.git', 'my-file']) // Expect both .git and user files to remain
     expect(git.tryClean).toHaveBeenCalled()
     expect(git.tryReset).toHaveBeenCalled()
     expect(core.warning).toHaveBeenCalled()
@@ -246,12 +338,13 @@ describe('git-directory-helper tests', () => {
       repositoryPath,
       repositoryUrl,
       clean,
-      ref
+      ref,
+      false // preserveLocalChanges = false
     )
 
     // Assert
     const files = await fs.promises.readdir(repositoryPath)
-    expect(files).toHaveLength(0)
+    expect(files).toEqual(['.git']) // Expect just the .git directory to remain
     expect(core.warning).not.toHaveBeenCalled()
   })
 
@@ -302,12 +395,13 @@ describe('git-directory-helper tests', () => {
       repositoryPath,
       repositoryUrl,
       clean,
-      ref
+      ref,
+      false // preserveLocalChanges = false
     )
 
     // Assert
     const files = await fs.promises.readdir(repositoryPath)
-    expect(files).toHaveLength(0)
+    expect(files).toEqual(['.git']) // Expect just the .git directory to remain
     expect(git.tryClean).toHaveBeenCalled()
   })
 

__test__/input-helper.test.ts

@@ -133,6 +133,16 @@ describe('input-helper tests', () => {
     expect(settings.commit).toBe('1111111111222222222233333333334444444444')
   })
 
+  it('sets ref to empty when explicit sha-256', async () => {
+    inputs.ref =
+      '1111111111222222222233333333334444444444555555555566666666667777'
+    const settings: IGitSourceSettings = await inputHelper.getInputs()
+    expect(settings.ref).toBeFalsy()
+    expect(settings.commit).toBe(
+      '1111111111222222222233333333334444444444555555555566666666667777'
+    )
+  })
+
   it('sets sha to empty when explicit ref', async () => {
     inputs.ref = 'refs/heads/some-other-ref'
     const settings: IGitSourceSettings = await inputHelper.getInputs()

__test__/ref-helper.test.ts

@@ -1,8 +1,12 @@
 import * as assert from 'assert'
+import * as core from '@actions/core'
+import * as github from '@actions/github'
 import * as refHelper from '../lib/ref-helper'
 import {IGitCommandManager} from '../lib/git-command-manager'
 
 const commit = '1234567890123456789012345678901234567890'
+const sha256Commit =
+  '1234567890123456789012345678901234567890123456789012345678901234'
 let git: IGitCommandManager
 
 describe('ref-helper tests', () => {
@@ -37,6 +41,12 @@ describe('ref-helper tests', () => {
     expect(checkoutInfo.startPoint).toBeFalsy()
   })
 
+  it('getCheckoutInfo sha-256 only', async () => {
+    const checkoutInfo = await refHelper.getCheckoutInfo(git, '', sha256Commit)
+    expect(checkoutInfo.ref).toBe(sha256Commit)
+    expect(checkoutInfo.startPoint).toBeFalsy()
+  })
+
   it('getCheckoutInfo refs/heads/', async () => {
     const checkoutInfo = await refHelper.getCheckoutInfo(
       git,
@@ -227,4 +237,142 @@ describe('ref-helper tests', () => {
       '+refs/heads/my/branch:refs/remotes/origin/my/branch'
     )
   })
+
+  describe('checkCommitInfo', () => {
+    const repositoryOwner = 'some-owner'
+    const repositoryName = 'some-repo'
+    const ref = 'refs/pull/123/merge'
+    const sha1Head = '1111111111222222222233333333334444444444'
+    const sha1Base = 'aaaaaaaaaabbbbbbbbbbccccccccccdddddddddd'
+    const sha256Head =
+      '1111111111222222222233333333334444444444555555555566666666667777'
+    const sha256Base =
+      'aaaaaaaaaabbbbbbbbbbccccccccccddddddddddeeeeeeeeeeffffffffff0000'
+    let debugSpy: jest.SpyInstance
+    let getOctokitSpy: jest.SpyInstance
+    let repoGetSpy: jest.Mock
+    let originalEventName: string
+    let originalPayload: unknown
+    let originalRef: string
+    let originalSha: string
+
+    function setPullRequestContext(
+      expectedHeadSha: string,
+      expectedBaseSha: string,
+      mergeCommit: string
+    ): void {
+      ;(github.context as any).eventName = 'pull_request'
+      github.context.ref = ref
+      github.context.sha = mergeCommit
+      ;(github.context as any).payload = {
+        action: 'synchronize',
+        after: expectedHeadSha,
+        number: 123,
+        pull_request: {
+          base: {
+            sha: expectedBaseSha
+          }
+        },
+        repository: {
+          private: false
+        }
+      }
+    }
+
+    beforeEach(() => {
+      originalEventName = github.context.eventName
+      originalPayload = github.context.payload
+      originalRef = github.context.ref
+      originalSha = github.context.sha
+
+      jest.spyOn(github.context, 'repo', 'get').mockReturnValue({
+        owner: repositoryOwner,
+        repo: repositoryName
+      })
+      debugSpy = jest.spyOn(core, 'debug').mockImplementation(jest.fn())
+      repoGetSpy = jest.fn(async () => ({}))
+      getOctokitSpy = jest.spyOn(github, 'getOctokit').mockReturnValue({
+        rest: {
+          repos: {
+            get: repoGetSpy
+          }
+        }
+      } as any)
+    })
+
+    afterEach(() => {
+      ;(github.context as any).eventName = originalEventName
+      ;(github.context as any).payload = originalPayload
+      github.context.ref = originalRef
+      github.context.sha = originalSha
+      jest.restoreAllMocks()
+    })
+
+    it('returns early for SHA-1 merge commit', async () => {
+      setPullRequestContext(sha1Head, sha1Base, commit)
+
+      await refHelper.checkCommitInfo(
+        'token',
+        `Merge ${sha1Head} into ${sha1Base}`,
+        repositoryOwner,
+        repositoryName,
+        ref,
+        commit
+      )
+
+      expect(getOctokitSpy).not.toHaveBeenCalled()
+      expect(repoGetSpy).not.toHaveBeenCalled()
+    })
+
+    it('matches SHA-256 merge commit info', async () => {
+      const actualHeadSha =
+        '9999999999888888888877777777776666666666555555555544444444443333'
+      setPullRequestContext(sha256Head, sha256Base, sha256Commit)
+
+      await refHelper.checkCommitInfo(
+        'token',
+        `Merge ${actualHeadSha} into ${sha256Base}`,
+        repositoryOwner,
+        repositoryName,
+        ref,
+        sha256Commit
+      )
+
+      expect(getOctokitSpy).toHaveBeenCalledWith(
+        'token',
+        expect.objectContaining({
+          userAgent: expect.stringContaining(
+            `expected_head_sha=${sha256Head};actual_head_sha=${actualHeadSha}`
+          )
+        })
+      )
+      expect(repoGetSpy).toHaveBeenCalledWith({
+        owner: repositoryOwner,
+        repo: repositoryName
+      })
+      expect(debugSpy).toHaveBeenCalledWith(
+        `Expected head sha ${sha256Head}; actual head sha ${actualHeadSha}`
+      )
+      expect(debugSpy).not.toHaveBeenCalledWith('Unexpected message format')
+    })
+
+    it('does not match 50-char hex as a valid merge', async () => {
+      const invalidHeadSha =
+        '99999999998888888888777777777766666666665555555555'
+      setPullRequestContext(sha1Head, sha1Base, commit)
+
+      await refHelper.checkCommitInfo(
+        'token',
+        `Merge ${invalidHeadSha} into ${sha1Base}`,
+        repositoryOwner,
+        repositoryName,
+        ref,
+        commit
+      )
+
+      expect(getOctokitSpy).not.toHaveBeenCalled()
+      expect(repoGetSpy).not.toHaveBeenCalled()
+      expect(debugSpy).toHaveBeenCalledWith('Unexpected message format')
+    })
+  })
 })

action.yml

@@ -56,7 +56,10 @@ inputs:
     description: 'Relative path under $GITHUB_WORKSPACE to place the repository'
   clean:
     description: 'Whether to execute `git clean -ffdx && git reset --hard HEAD` before fetching'
-    default: true
+    default: 'true'
+  preserve-local-changes:
+    description: 'Whether to preserve local changes during checkout. If true, tries to preserve local files that are not tracked by Git. By default, all files will be overwritten.'
+    default: 'false'
   filter:
     description: >
       Partially clone against a given filter.

dist/index.js

@@ -780,9 +780,17 @@ class GitCommandManager {
             yield fs.promises.appendFile(sparseCheckoutPath, `\n${sparseCheckout.join('\n')}\n`);
         });
     }
-    checkout(ref, startPoint) {
+    checkout(ref_1, startPoint_1) {
-        return __awaiter(this, void 0, void 0, function* () {
+        return __awaiter(this, arguments, void 0, function* (ref, startPoint, options = []) {
-            const args = ['checkout', '--progress', '--force'];
+            const args = ['checkout', '--progress'];
+            // Add custom options (like --merge) if provided
+            if (options.length > 0) {
+                args.push(...options);
+            }
+            else {
+                // Default behavior - use force
+                args.push('--force');
+            }
             if (startPoint) {
                 args.push('-B', ref, startPoint);
             }
@@ -1276,13 +1284,17 @@ const fs = __importStar(__nccwpck_require__(7147));
 const fsHelper = __importStar(__nccwpck_require__(7219));
 const io = __importStar(__nccwpck_require__(7436));
 const path = __importStar(__nccwpck_require__(1017));
-function prepareExistingDirectory(git, repositoryPath, repositoryUrl, clean, ref) {
+function prepareExistingDirectory(git_1, repositoryPath_1, repositoryUrl_1, clean_1, ref_1) {
-    return __awaiter(this, void 0, void 0, function* () {
+    return __awaiter(this, arguments, void 0, function* (git, repositoryPath, repositoryUrl, clean, ref, preserveLocalChanges = false) {
         var _a;
         assert.ok(repositoryPath, 'Expected repositoryPath to be defined');
         assert.ok(repositoryUrl, 'Expected repositoryUrl to be defined');
         // Indicates whether to delete the directory contents
         let remove = false;
+        // If preserveLocalChanges is true, log it
+        if (preserveLocalChanges) {
+            core.info(`Preserve local changes is enabled, will attempt to keep local files`);
+        }
         // Check whether using git or REST API
         if (!git) {
             remove = true;
@@ -1363,14 +1375,28 @@ function prepareExistingDirectory(git, repositoryPath, repositoryUrl, clean, ref
                 remove = true;
             }
         }
-        if (remove) {
+        if (remove && !preserveLocalChanges) {
             // Delete the contents of the directory. Don't delete the directory itself
             // since it might be the current working directory.
             core.info(`Deleting the contents of '${repositoryPath}'`);
             for (const file of yield fs.promises.readdir(repositoryPath)) {
+                // Skip .git directory as we need it to determine if a file is tracked
+                if (file === '.git') {
+                    continue;
+                }
                 yield io.rmRF(path.join(repositoryPath, file));
             }
         }
+        else if (remove && preserveLocalChanges) {
+            core.info(`Skipping deletion of directory contents due to preserve-local-changes setting`);
+            // We still need to make sure we have a git repository to work with
+            if (!git) {
+                core.info(`Initializing git repository to prepare for checkout with preserved changes`);
+                yield fs.promises.mkdir(path.join(repositoryPath, '.git'), {
+                    recursive: true
+                });
+            }
+        }
     });
 }
 
@@ -1467,7 +1493,7 @@ function getSource(settings) {
             }
             // Prepare existing directory, otherwise recreate
             if (isExisting) {
-                yield gitDirectoryHelper.prepareExistingDirectory(git, settings.repositoryPath, repositoryUrl, settings.clean, settings.ref);
+                yield gitDirectoryHelper.prepareExistingDirectory(git, settings.repositoryPath, repositoryUrl, settings.clean, settings.ref, settings.preserveLocalChanges);
             }
             if (!git) {
                 // Downloading using REST API
@@ -1593,7 +1619,104 @@ function getSource(settings) {
             }
             // Checkout
             core.startGroup('Checking out the ref');
-            yield git.checkout(checkoutInfo.ref, checkoutInfo.startPoint);
+            if (settings.preserveLocalChanges) {
+                core.info('Attempting to preserve local changes during checkout');
+                // List and store local files before checkout
+                const fs = __nccwpck_require__(7147);
+                const path = __nccwpck_require__(1017);
+                const localFiles = new Map();
+                try {
+                    // Get all files in the workspace that aren't in the .git directory
+                    const workspacePath = process.cwd();
+                    core.info(`Current workspace path: ${workspacePath}`);
+                    // List all files in the current directory using fs
+                    const listFilesRecursively = (dir) => {
+                        let results = [];
+                        const list = fs.readdirSync(dir);
+                        list.forEach((file) => {
+                            const fullPath = path.join(dir, file);
+                            const relativePath = path.relative(workspacePath, fullPath);
+                            // Skip .git directory
+                            if (relativePath.startsWith('.git'))
+                                return;
+                            const stat = fs.statSync(fullPath);
+                            if (stat && stat.isDirectory()) {
+                                // Recursively explore subdirectories
+                                results = results.concat(listFilesRecursively(fullPath));
+                            }
+                            else {
+                                // Store file content in memory
+                                try {
+                                    const content = fs.readFileSync(fullPath);
+                                    localFiles.set(relativePath, content);
+                                    results.push(relativePath);
+                                }
+                                catch (readErr) {
+                                    core.warning(`Failed to read file ${relativePath}: ${readErr}`);
+                                }
+                            }
+                        });
+                        return results;
+                    };
+                    const localFilesList = listFilesRecursively(workspacePath);
+                    core.info(`Found ${localFilesList.length} local files to preserve:`);
+                    localFilesList.forEach(file => core.info(`  - ${file}`));
+                }
+                catch (error) {
+                    core.warning(`Failed to list local files: ${error}`);
+                }
+                // Perform normal checkout
+                yield git.checkout(checkoutInfo.ref, checkoutInfo.startPoint);
+                // Restore local files that were not tracked by git
+                core.info('Restoring local files after checkout');
+                try {
+                    let restoredCount = 0;
+                    const execOptions = {
+                        cwd: process.cwd(),
+                        silent: true,
+                        ignoreReturnCode: true
+                    };
+                    for (const [filePath, content] of localFiles.entries()) {
+                        // Check if file exists in git using a child process instead of git.execGit
+                        const { exec } = __nccwpck_require__(1514);
+                        let exitCode = 0;
+                        const output = {
+                            stdout: '',
+                            stderr: ''
+                        };
+                        // Capture output
+                        const options = Object.assign(Object.assign({}, execOptions), { listeners: {
+                                stdout: (data) => {
+                                    output.stdout += data.toString();
+                                },
+                                stderr: (data) => {
+                                    output.stderr += data.toString();
+                                }
+                            } });
+                        exitCode = yield exec('git', ['ls-files', '--error-unmatch', filePath], options);
+                        if (exitCode !== 0) {
+                            // File is not tracked by git, safe to restore
+                            const fullPath = path.join(process.cwd(), filePath);
+                            // Ensure directory exists
+                            fs.mkdirSync(path.dirname(fullPath), { recursive: true });
+                            fs.writeFileSync(fullPath, content);
+                            core.info(`Restored local file: ${filePath}`);
+                            restoredCount++;
+                        }
+                        else {
+                            core.info(`Skipping ${filePath} as it's tracked by git`);
+                        }
+                    }
+                    core.info(`Successfully restored ${restoredCount} local files`);
+                }
+                catch (error) {
+                    core.warning(`Failed to restore local files: ${error}`);
+                }
+            }
+            else {
+                // Use the default behavior with --force
+                yield git.checkout(checkoutInfo.ref, checkoutInfo.startPoint);
+            }
             core.endGroup();
             // Submodules
             if (settings.submodules) {
@@ -2021,7 +2144,7 @@ function getInputs() {
             }
         }
         // SHA?
-        else if (result.ref.match(/^[0-9a-fA-F]{40}$/)) {
+        else if (result.ref.match(/^(?:[0-9a-fA-F]{40}|[0-9a-fA-F]{64})$/)) {
             result.commit = result.ref;
             result.ref = '';
         }
@@ -2030,6 +2153,11 @@ function getInputs() {
         // Clean
         result.clean = (core.getInput('clean') || 'true').toUpperCase() === 'TRUE';
         core.debug(`clean = ${result.clean}`);
+        // Preserve local changes
+        result.preserveLocalChanges =
+            (core.getInput('preserve-local-changes') || 'false').toUpperCase() ===
+                'TRUE';
+        core.debug(`preserveLocalChanges = ${result.preserveLocalChanges}`);
         // Filter
         const filter = core.getInput('filter');
         if (filter) {
@@ -2444,7 +2572,7 @@ function checkCommitInfo(token, commitInfo, repositoryOwner, repositoryName, ref
                 return;
             }
             // Extract details from message
-            const match = commitInfo.match(/Merge ([0-9a-f]{40}) into ([0-9a-f]{40})/);
+            const match = commitInfo.match(/Merge ([0-9a-f]{40}|[0-9a-f]{64}) into ([0-9a-f]{40}|[0-9a-f]{64})/);
             if (!match) {
                 core.debug('Unexpected message format');
                 return;

src/git-command-manager.ts

@@ -22,7 +22,7 @@ export interface IGitCommandManager {
   disableSparseCheckout(): Promise<void>
   sparseCheckout(sparseCheckout: string[]): Promise<void>
   sparseCheckoutNonConeMode(sparseCheckout: string[]): Promise<void>
-  checkout(ref: string, startPoint: string): Promise<void>
+  checkout(ref: string, startPoint: string, options?: string[]): Promise<void>
   checkoutDetach(): Promise<void>
   config(
     configKey: string,
@@ -220,8 +220,21 @@ class GitCommandManager {
     )
   }
 
-  async checkout(ref: string, startPoint: string): Promise<void> {
+  async checkout(
-    const args = ['checkout', '--progress', '--force']
+    ref: string,
+    startPoint: string,
+    options: string[] = []
+  ): Promise<void> {
+    const args = ['checkout', '--progress']
+
+    // Add custom options (like --merge) if provided
+    if (options.length > 0) {
+      args.push(...options)
+    } else {
+      // Default behavior - use force
+      args.push('--force')
+    }
+
     if (startPoint) {
       args.push('-B', ref, startPoint)
     } else {

src/git-directory-helper.ts

@@ -11,7 +11,8 @@ export async function prepareExistingDirectory(
   repositoryPath: string,
   repositoryUrl: string,
   clean: boolean,
-  ref: string
+  ref: string,
+  preserveLocalChanges: boolean = false
 ): Promise<void> {
   assert.ok(repositoryPath, 'Expected repositoryPath to be defined')
   assert.ok(repositoryUrl, 'Expected repositoryUrl to be defined')
@@ -19,6 +20,13 @@ export async function prepareExistingDirectory(
   // Indicates whether to delete the directory contents
   let remove = false
 
+  // If preserveLocalChanges is true, log it
+  if (preserveLocalChanges) {
+    core.info(
+      `Preserve local changes is enabled, will attempt to keep local files`
+    )
+  }
+
   // Check whether using git or REST API
   if (!git) {
     remove = true
@@ -114,12 +122,43 @@ export async function prepareExistingDirectory(
     }
   }
 
-  if (remove) {
+  // Check repository conditions
+  let isLocalGitRepo = git && fsHelper.directoryExistsSync(path.join(repositoryPath, '.git'));
+  let repoUrl = isLocalGitRepo ? await git?.tryGetFetchUrl() : '';
+  let isSameRepository = repositoryUrl === repoUrl;
+  let differentRepoUrl = !isSameRepository;
+
+  // Repository URL has changed
+  if (differentRepoUrl) {
+    if (preserveLocalChanges) {
+      core.warning(`Repository URL has changed from '${repoUrl}' to '${repositoryUrl}'. Local changes will be preserved as requested.`);
+    }
+    remove = true; // Mark for removal, but actual removal will respect preserveLocalChanges
+  }
+
+  if (remove && !preserveLocalChanges) {
     // Delete the contents of the directory. Don't delete the directory itself
     // since it might be the current working directory.
     core.info(`Deleting the contents of '${repositoryPath}'`)
     for (const file of await fs.promises.readdir(repositoryPath)) {
+      // Skip .git directory as we need it to determine if a file is tracked
+      if (file === '.git') {
+        continue
+      }
       await io.rmRF(path.join(repositoryPath, file))
     }
+  } else if (remove && preserveLocalChanges) {
+    core.info(
+      `Skipping deletion of directory contents due to preserve-local-changes setting`
+    )
+    // We still need to make sure we have a git repository to work with
+    if (!git) {
+      core.info(
+        `Initializing git repository to prepare for checkout with preserved changes`
+      )
+      await fs.promises.mkdir(path.join(repositoryPath, '.git'), {
+        recursive: true
+      })
+    }
   }
 }

src/git-source-provider.ts

@@ -70,7 +70,8 @@ export async function getSource(settings: IGitSourceSettings): Promise<void> {
         settings.repositoryPath,
         repositoryUrl,
         settings.clean,
-        settings.ref
+        settings.ref,
+        settings.preserveLocalChanges
       )
     }
 
@@ -251,7 +252,115 @@ export async function getSource(settings: IGitSourceSettings): Promise<void> {
 
     // Checkout
     core.startGroup('Checking out the ref')
-    await git.checkout(checkoutInfo.ref, checkoutInfo.startPoint)
+    if (settings.preserveLocalChanges) {
+      core.info('Attempting to preserve local changes during checkout')
+
+      // List and store local files before checkout
+      const fs = require('fs')
+      const path = require('path')
+      const localFiles = new Map()
+
+      try {
+        // Get all files in the workspace that aren't in the .git directory
+        const workspacePath = process.cwd()
+        core.info(`Current workspace path: ${workspacePath}`)
+
+        // List all files in the current directory using fs
+        const listFilesRecursively = (dir: string): string[] => {
+          let results: string[] = []
+          const list = fs.readdirSync(dir)
+          list.forEach((file: string) => {
+            const fullPath = path.join(dir, file)
+            const relativePath = path.relative(workspacePath, fullPath)
+            // Skip .git directory
+            if (relativePath.startsWith('.git')) return
+
+            const stat = fs.statSync(fullPath)
+            if (stat && stat.isDirectory()) {
+              // Recursively explore subdirectories
+              results = results.concat(listFilesRecursively(fullPath))
+            } else {
+              // Store file content in memory
+              try {
+                const content = fs.readFileSync(fullPath)
+                localFiles.set(relativePath, content)
+                results.push(relativePath)
+              } catch (readErr) {
+                core.warning(`Failed to read file ${relativePath}: ${readErr}`)
+              }
+            }
+          })
+          return results
+        }
+
+        const localFilesList = listFilesRecursively(workspacePath)
+        core.info(`Found ${localFilesList.length} local files to preserve:`)
+        localFilesList.forEach(file => core.info(`  - ${file}`))
+      } catch (error) {
+        core.warning(`Failed to list local files: ${error}`)
+      }
+
+      // Perform normal checkout
+      await git.checkout(checkoutInfo.ref, checkoutInfo.startPoint)
+
+      // Restore local files that were not tracked by git
+      core.info('Restoring local files after checkout')
+      try {
+        let restoredCount = 0
+        const execOptions = {
+          cwd: process.cwd(),
+          silent: true,
+          ignoreReturnCode: true
+        }
+
+        for (const [filePath, content] of localFiles.entries()) {
+          // Check if file exists in git using a child process instead of git.execGit
+          const {exec} = require('@actions/exec')
+          let exitCode = 0
+          const output = {
+            stdout: '',
+            stderr: ''
+          }
+
+          // Capture output
+          const options = {
+            ...execOptions,
+            listeners: {
+              stdout: (data: Buffer) => {
+                output.stdout += data.toString()
+              },
+              stderr: (data: Buffer) => {
+                output.stderr += data.toString()
+              }
+            }
+          }
+
+          exitCode = await exec(
+            'git',
+            ['ls-files', '--error-unmatch', filePath],
+            options
+          )
+
+          if (exitCode !== 0) {
+            // File is not tracked by git, safe to restore
+            const fullPath = path.join(process.cwd(), filePath)
+            // Ensure directory exists
+            fs.mkdirSync(path.dirname(fullPath), {recursive: true})
+            fs.writeFileSync(fullPath, content)
+            core.info(`Restored local file: ${filePath}`)
+            restoredCount++
+          } else {
+            core.info(`Skipping ${filePath} as it's tracked by git`)
+          }
+        }
+        core.info(`Successfully restored ${restoredCount} local files`)
+      } catch (error) {
+        core.warning(`Failed to restore local files: ${error}`)
+      }
+    } else {
+      // Use the default behavior with --force
+      await git.checkout(checkoutInfo.ref, checkoutInfo.startPoint)
+    }
     core.endGroup()
 
     // Submodules

src/git-source-settings.ts

@@ -25,10 +25,15 @@ export interface IGitSourceSettings {
   commit: string
 
   /**
-   * Indicates whether to clean the repository
+   * Whether to execute git clean and git reset before fetching
    */
   clean: boolean
 
+  /**
+   * Whether to preserve local changes during checkout
+   */
+  preserveLocalChanges: boolean
+
   /**
    * The filter determining which objects to include
    */

src/input-helper.ts

@@ -71,7 +71,7 @@ export async function getInputs(): Promise<IGitSourceSettings> {
     }
   }
   // SHA?
-  else if (result.ref.match(/^[0-9a-fA-F]{40}$/)) {
+  else if (result.ref.match(/^(?:[0-9a-fA-F]{40}|[0-9a-fA-F]{64})$/)) {
     result.commit = result.ref
     result.ref = ''
   }
@@ -82,6 +82,12 @@ export async function getInputs(): Promise<IGitSourceSettings> {
   result.clean = (core.getInput('clean') || 'true').toUpperCase() === 'TRUE'
   core.debug(`clean = ${result.clean}`)
 
+  // Preserve local changes
+  result.preserveLocalChanges =
+    (core.getInput('preserve-local-changes') || 'false').toUpperCase() ===
+    'TRUE'
+  core.debug(`preserveLocalChanges = ${result.preserveLocalChanges}`)
+
   // Filter
   const filter = core.getInput('filter')
   if (filter) {

src/ref-helper.ts

@@ -258,7 +258,9 @@ export async function checkCommitInfo(
     }
 
     // Extract details from message
-    const match = commitInfo.match(/Merge ([0-9a-f]{40}) into ([0-9a-f]{40})/)
+    const match = commitInfo.match(
+      /Merge ([0-9a-f]{40}|[0-9a-f]{64}) into ([0-9a-f]{40}|[0-9a-f]{64})/
+    )
     if (!match) {
       core.debug('Unexpected message format')
       return