Feat/1074 branch show current (#1083)

* Add support for `git.branch` parsing the single-line response to `branch --show-current`.

* Changeset

* Configure git for use before testing

Author: steveukx

.changeset/nasty-bikes-say.md

@@ -0,0 +1,7 @@
+---
+"simple-git": minor
+---
+
+Support the use of `git.branch(['--show-current'])` to limit the branch list to only the current branch.
+
+Thanks to @peterbe for pointing out the use-case.

biome.json

@@ -131,8 +131,9 @@
       "**/*.ts",
       "**/*.json",
       "**/*.yml",
-      "!node_modules/**",
-      "!.changeset/**"
+      "!**/coverage/**",
+      "!.changeset/**",
+      "!node_modules/**"
     ]
   }
 }

simple-git/src/lib/parsers/parse-branch.ts

@@ -1,5 +1,5 @@
 import type { BranchSummary } from '../../../typings';
-import { BranchSummaryResult } from '../responses/BranchSummary';
+import { BranchStatusIdentifier, BranchSummaryResult } from '../responses/BranchSummary';
 import { LineParser, parseStringResponse } from '../utils';
 
 const parsers: LineParser<BranchSummaryResult>[] = [
@@ -17,10 +17,18 @@ const parsers: LineParser<BranchSummaryResult>[] = [
    ),
 ];
 
+const currentBranchParser = new LineParser<BranchSummaryResult>(/^(\S+)$/s, (result, [name]) => {
+   result.push(BranchStatusIdentifier.CURRENT, false, name, '', '');
+});
+
 function branchStatus(input?: string) {
    return input ? input.charAt(0) : '';
 }
 
-export function parseBranchSummary(stdOut: string): BranchSummary {
-   return parseStringResponse(new BranchSummaryResult(), parsers, stdOut);
+export function parseBranchSummary(stdOut: string, currentOnly = false): BranchSummary {
+   return parseStringResponse(
+      new BranchSummaryResult(),
+      currentOnly ? [currentBranchParser] : parsers,
+      stdOut
+   );
 }

simple-git/src/lib/tasks/branch.ts

@@ -14,6 +14,8 @@ export function branchTask(
    customArgs: string[]
 ): StringTask<BranchSummary | BranchSingleDeleteResult> {
    const isDelete = containsDeleteBranchCommand(customArgs);
+   const isCurrentOnly = customArgs.includes('--show-current');
+
    const commands = ['branch', ...customArgs];
 
    if (commands.length === 1) {
@@ -32,18 +34,18 @@ export function branchTask(
             return parseBranchDeletions(stdOut, stdErr).all[0];
          }
 
-         return parseBranchSummary(stdOut);
+         return parseBranchSummary(stdOut, isCurrentOnly);
       },
    };
 }
 
 export function branchLocalTask(): StringTask<BranchSummary> {
-   const parser = parseBranchSummary;
-
    return {
       format: 'utf-8',
       commands: ['branch', '-v'],
-      parser,
+      parser(stdOut) {
+         return parseBranchSummary(stdOut);
+      },
    };
 }
 

simple-git/test/integration/branches-show-current.spec.ts

@@ -0,0 +1,44 @@
+import { createTestContext, like, setUpFilesAdded, setUpInit, SimpleGitTestContext } from '@simple-git/test-utils';
+
+describe('branch-show-current', () => {
+   let context: SimpleGitTestContext;
+
+   const expectedBranchSummary = (commit = '', label = '') => like({
+      all: ['my-new-branch'],
+      current: 'my-new-branch',
+      branches: {
+         'my-new-branch': {
+            name: 'my-new-branch',
+            commit,
+            label,
+            current: true,
+            linkedWorkTree: false,
+         },
+      },
+   });
+
+
+   beforeEach(async () => (context = await createTestContext()));
+   beforeEach(async () => {
+      await setUpInit(context);
+      await context.git.raw('checkout', '-b', 'my-new-branch');
+   });
+
+   it('should be able to show you the current on an empty repo', async () => {
+      expect(await context.git.branch(['--show-current']))
+         .toEqual(expectedBranchSummary());
+   });
+
+   it('should be able to show you the current on an regular repo', async () => {
+      await setUpFilesAdded(context, ['some-file'], '.', 'Initial Commit');
+
+      expect(await context.git.branch(['--show-current']))
+         .toEqual(expectedBranchSummary());
+
+      const branch = await context.git.branch();
+      expect(branch).toEqual(expectedBranchSummary(
+         expect.stringMatching(/^.{7}$/),
+         'Initial Commit',
+      ));
+   });
+});