Add repo.currentBranch() method

Author: lahmatiy

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## next
 
+- 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
 

README.md

@@ -57,6 +57,19 @@ The algorithm to identify a default branch name:
   - `main`
   - `master`
 
+#### repo.currentBranch()
+
+Returns the current branch name along with its commit oid.
+If the repository is in a detached HEAD state, `name` will be `null`.
+
+```js
+const currentBranch = repo.currentBranch();
+// { name: 'main', oid: '8bb6e23769902199e39ab70f2441841712cbdd62' }
+
+const detachedHead = repo.currentBranch();
+// { name: null, oid: '8bb6e23769902199e39ab70f2441841712cbdd62' }
+```
+
 #### repo.isRefExists(ref)
 
 Checks if a `ref` exists.

fixtures/base/collect-data.js

@@ -4,6 +4,8 @@ import { fileURLToPath } from 'url';
 import { createGitReader, parseTree } from '../../lib/index.js';
 
 const repo = await createGitReader(fileURLToPath(new URL('_git', import.meta.url)));
+const defaultBranch = await repo.defaultBranch();
+const currentBranch = await repo.currentBranch();
 const commits = await repo.log();
 const stat = await repo.stat();
 const objects = {};
@@ -38,6 +40,8 @@ fs.writeFileSync(
     fileURLToPath(new URL('data.json', import.meta.url)),
     JSON.stringify(
         {
+            defaultBranch,
+            currentBranch,
             commits,
             filesLists,
             filesDelta,

fixtures/base/data.json

@@ -1,4 +1,9 @@
 {
+    "defaultBranch": "main",
+    "currentBranch": {
+        "name": "test",
+        "oid": "2dbee47a8d4f8d39e1168fad951b703ee05614d6"
+    },
     "commits": [
         {
             "oid": "2dbee47a8d4f8d39e1168fad951b703ee05614d6",

fixtures/clean/_git/HEAD

@@ -1 +1 @@
-ref: refs/heads/development
+ref: refs/heads/empty-branch

src/resolve-ref.ts

@@ -90,7 +90,6 @@ export async function createRefIndex(gitdir: string) {
         }
 
         const refInfo = await refResolver.resolve(expandedRef);
-
         const [, scope, path] = expandedRef.match(/^([^/]+\/[^/]+)\/(.+)$/) || [
             '',
             'refs/heads',
@@ -163,6 +162,37 @@ export async function createRefIndex(gitdir: string) {
                 .replace(/^ref:\s*/, '')
         );
 
+    const currentBranch = async function () {
+        const { ref, oid } = await describeRef('HEAD');
+        const name = ref ? (await describeRef(ref)).name : null;
+
+        return {
+            name,
+            oid
+        };
+    };
+
+    // inspired by https://usethis.r-lib.org/reference/git-default-branch.html
+    const defaultBranch = async function () {
+        const branches = (await listBranches()) as string[]; // FIXME: remove string[]
+
+        if (branches.length <= 1) {
+            return basename(branches[0]);
+        }
+
+        const branchRef =
+            expandRef('refs/remotes/upstream/HEAD') ||
+            expandRef('refs/remotes/origin/HEAD') ||
+            expandRef('refs/heads/main') ||
+            expandRef('refs/heads/master');
+
+        if (branchRef) {
+            return branchRef.endsWith('/HEAD') ? readRefContent(branchRef) : basename(branchRef);
+        }
+
+        return null;
+    };
+
     return {
         isOid,
         isRefExists: (ref: string) => expandRef(ref) !== null,
@@ -175,28 +205,8 @@ export async function createRefIndex(gitdir: string) {
         listBranches,
         listTags,
 
-        // inspired by https://usethis.r-lib.org/reference/git-default-branch.html
-        async defaultBranch() {
-            const branches = (await listBranches()) as string[]; // FIXME: remove string[]
-
-            if (branches.length === 1) {
-                return basename(branches[0]);
-            }
-
-            const branchRef =
-                expandRef('refs/remotes/upstream/HEAD') ||
-                expandRef('refs/remotes/origin/HEAD') ||
-                expandRef('refs/heads/main') ||
-                expandRef('refs/heads/master');
-
-            if (branchRef) {
-                return branchRef.endsWith('/HEAD')
-                    ? readRefContent(branchRef)
-                    : basename(branchRef);
-            }
-
-            return null;
-        },
+        defaultBranch,
+        currentBranch,
 
         async stat() {
             const remotes = listRemotes();

test/resolve-ref.ts

@@ -16,10 +16,11 @@ describe('resolve-ref', () => {
     describe('defaultBranch()', () => {
         const defaultBranches = {
             base: 'main',
+            detached: 'main',
             cruft: 'main',
             'no-remotes': 'main',
             upstream: 'fork-main',
-            clean: 'development' // FIXME
+            clean: 'empty-branch' // FIXME
         };
 
         for (const [repoName, expected] of Object.entries(defaultBranches)) {
@@ -34,6 +35,28 @@ describe('resolve-ref', () => {
         }
     });
 
+    describe('currentBranch()', () => {
+        const defaultBranches = {
+            base: { name: 'test', oid: '2dbee47a8d4f8d39e1168fad951b703ee05614d6' },
+            detached: { name: null, oid: '2dbee47a8d4f8d39e1168fad951b703ee05614d6' },
+            cruft: { name: 'main', oid: '7b84f676f2fbea2a3c6d83924fa63059c7bdfbe2' },
+            'no-remotes': { name: 'main', oid: '293e1ffaf7158c249fc654aec07eca555a25de09' },
+            upstream: { name: 'fork-main', oid: '293e1ffaf7158c249fc654aec07eca555a25de09' },
+            clean: { name: 'empty-branch', oid: null } // FIXME
+        };
+
+        for (const [repoName, expected] of Object.entries(defaultBranches)) {
+            (repoName === 'clean' ? it.skip : it)(repoName, async () => {
+                const repo = await fixtures[repoName].repo();
+                const actual = await repo.currentBranch();
+
+                assert.deepStrictEqual(actual, expected);
+
+                return repo.dispose();
+            });
+        }
+    });
+
     describe('listBranches()', () => {
         it('local branches', async () => {
             const actual = await repo.listBranches();