Enhance createGitReader() to automatically attempt adding the .git folder, add isGitDir() and resolveGitDir()

Author: lahmatiy

CHANGELOG.md

@@ -3,6 +3,8 @@
 - Added `repo.currentBranch()` method
 - Added `repo.describeRef(ref)` method, which returns an information object about the reference
 - Added `repo.isOid(value)` method to check if a value is an object ID
+- Added `isGitDir()` and `resolveGitDir()` helper functions
+- Enhanced `createGitReader()` to automatically attempt adding the `.git` folder to the provided `gitdir` path, making explicit inclusion of `.git` optional
 
 ## 0.1.3 (2023-10-13)
 

src/gitdir.ts

@@ -0,0 +1,44 @@
+import { stat } from 'fs/promises';
+import { join, resolve } from 'path';
+
+const test = {
+    objects: 'dir',
+    refs: 'dir',
+    HEAD: 'file',
+    config: 'file'
+};
+
+export async function isGitDir(dir: string) {
+    try {
+        const stats = await Promise.all(Object.keys(test).map((name) => stat(join(dir, name))));
+
+        return Object.values(test).every((type, idx) =>
+            type === 'dir' ? stats[idx].isDirectory() : stats[idx].isFile()
+        );
+    } catch {
+        return false;
+    }
+}
+
+export async function resolveGitDir(dir: string) {
+    const absdir = resolve(process.cwd(), dir);
+    let absdirStat;
+
+    try {
+        absdirStat = await stat(absdir);
+    } catch {
+        throw new Error(`No such directory "${absdir}"`);
+    }
+
+    if (!absdirStat.isDirectory()) {
+        throw new Error(`Not a directory "${absdir}"`);
+    }
+
+    try {
+        const dotGitDir = join(absdir, '.git');
+        await stat(dotGitDir);
+        return dotGitDir;
+    } catch {}
+
+    return absdir;
+}

src/index.ts

@@ -1,3 +1,4 @@
+import { isGitDir, resolveGitDir } from './gitdir.js';
 import { createReadObject } from './read-object.js';
 import { createRefIndex } from './resolve-ref.js';
 import { createLooseObjectIndex } from './loose-object-index.js';
@@ -9,21 +10,23 @@ import { GitReaderOptions, NormalizedGitReaderOptions, CruftPackMode } from './t
 
 export * from './types.js';
 export * from './parse-object.js';
+export { isGitDir, resolveGitDir };
 
 export async function createGitReader(gitdir: string, options?: GitReaderOptions) {
     const startInitTime = Date.now();
     const normalizedOptions = normalizeOptions(options);
+    const resolvedGitDir = await resolveGitDir(gitdir);
     const [refIndex, looseObjectIndex, packedObjectIndex] = await Promise.all([
-        createRefIndex(gitdir),
-        createLooseObjectIndex(gitdir),
-        createPackedObjectIndex(gitdir, normalizedOptions)
+        createRefIndex(resolvedGitDir),
+        createLooseObjectIndex(resolvedGitDir),
+        createPackedObjectIndex(resolvedGitDir, normalizedOptions)
     ]);
     const { readObjectHeaderByHash, readObjectByHash, readObjectHeaderByOid, readObjectByOid } =
         createReadObject(looseObjectIndex, packedObjectIndex);
 
     return {
         get gitdir() {
-            return gitdir;
+            return resolvedGitDir;
         },
         readObjectHeaderByHash,
         readObjectByHash,
@@ -35,7 +38,12 @@ export async function createGitReader(gitdir: string, options?: GitReaderOptions
         async dispose() {
             await Promise.all([looseObjectIndex.dispose(), packedObjectIndex.dispose()]);
         },
-        stat: createStatMethod({ gitdir, refIndex, looseObjectIndex, packedObjectIndex }),
+        stat: createStatMethod({
+            gitdir: resolvedGitDir,
+            refIndex,
+            looseObjectIndex,
+            packedObjectIndex
+        }),
 
         initTime: Date.now() - startInitTime
     };

test/gitdir.ts

@@ -0,0 +1,64 @@
+import assert from 'assert';
+import path from 'path';
+import { isGitDir, resolveGitDir } from '@discoveryjs/scan-git';
+
+const cwd = process.cwd();
+const gitdir = path.join(cwd, '.git');
+
+describe('Git Directory Utilities', () => {
+    describe('isGitDir()', () => {
+        it('should return false for non-Git directory', async () => {
+            const actual = await isGitDir(cwd);
+            assert.strictEqual(actual, false);
+        });
+
+        it('should return true for valid Git directory', async () => {
+            const actual = await isGitDir(gitdir);
+            assert.strictEqual(actual, true);
+        });
+    });
+
+    describe('resolveGitDir()', () => {
+        describe('absolute paths', () => {
+            it('should resolve current working directory to Git directory', async () => {
+                const actual = await resolveGitDir(cwd);
+                assert.strictEqual(actual, gitdir);
+            });
+
+            it('should resolve .git directory path to itself', async () => {
+                const actual = await resolveGitDir(gitdir);
+                assert.strictEqual(actual, gitdir);
+            });
+        });
+
+        describe('relative paths', () => {
+            it('should resolve empty path to Git directory', async () => {
+                const actual = await resolveGitDir('');
+                assert.strictEqual(actual, gitdir);
+            });
+
+            it('should resolve .git relative path to Git directory', async () => {
+                const actual = await resolveGitDir('.git');
+                assert.strictEqual(actual, gitdir);
+            });
+        });
+
+        it('should throws for non existing paths', () => {
+            const testdir = path.resolve(cwd, 'non-exists');
+
+            return assert.rejects(
+                () => resolveGitDir(testdir),
+                (e: Error) => e.message.endsWith(`No such directory "${testdir}"`)
+            );
+        });
+
+        it('should throws for non directory paths', () => {
+            const testpath = path.resolve(cwd, 'package.json');
+
+            return assert.rejects(
+                () => resolveGitDir(testpath),
+                (e: Error) => e.message.endsWith(`Not a directory "${testpath}"`)
+            );
+        });
+    });
+});