fix: make git diff relative to current working directory (#11)

* fix: make git diff relative to current working directory

* fix test

* add extra test to ensure it works with both relative and absolute cwd path

* refactor path resolving of cwd for git diff command

---------

Co-authored-by: Yann-Fanch GUYOT <yfguyot@afoneinfrastructure.com>

libs/core/src/git.spec.ts

@@ -4,6 +4,7 @@ import { readFile, writeFile } from 'fs/promises';
 import * as childProcess from 'node:child_process';
 
 const cwd = 'libs/core/src/__fixtures__/git';
+const absoluteCwd = resolve(cwd);
 const branch = 'main';
 
 describe('git', () => {
@@ -115,7 +116,7 @@ describe('git', () => {
   });
 
   describe('getChangedFiles', () => {
-    it('should return changed files with line numbers', () => {
+    it('should return changed files with line numbers from relative cwd path', () => {
       const changedFiles = getChangedFiles({
         base: branch,
         cwd,
@@ -129,6 +130,20 @@ describe('git', () => {
       ]);
     });
 
+    it('should return changed files with line numbers from absolute cwd path', () => {
+      const changedFiles = getChangedFiles({
+        base: branch,
+        cwd: absoluteCwd,
+      });
+
+      expect(changedFiles).toEqual([
+        {
+          filePath: 'index.ts',
+          changedLines: [3],
+        },
+      ]);
+    });
+
     it('should return empty array if no files changed', async () => {
       await restoreFile();
 

libs/core/src/git.ts

@@ -1,4 +1,5 @@
 import { execSync } from 'node:child_process';
+import { resolve } from 'node:path';
 
 const TEN_MEGABYTES = 1024 * 10000;
 
@@ -41,7 +42,11 @@ export function getMergeBase({
 
 export function getDiff({ base, cwd }: BaseGitActionArgs): string {
   try {
-    return execSync(`git diff ${base} --unified=0`, {
+    const diffCommand = cwd
+      ? `git diff ${base} --unified=0 --relative -- ${resolve(cwd)}`
+      : `git diff ${base} --unified=0 `;
+
+    return execSync(diffCommand, {
       maxBuffer: TEN_MEGABYTES,
       cwd,
       stdio: 'pipe',