Fix missing revision git diff error

__tests__/main.test.ts

@@ -13,7 +13,7 @@ import {
   writeFile
 } from 'node:fs/promises'
 import { join } from 'node:path'
-import { simpleGit, type SimpleGit } from 'simple-git'
+import { simpleGit, type DiffResult, type SimpleGit } from 'simple-git'
 import type { ActionInputs } from '../src/inputs'
 import { run } from '../src/main'
 
@@ -127,6 +127,9 @@ describe('code-pushup action', () => {
     git = simpleGit(workDir)
 
     jest.spyOn(git, 'fetch').mockImplementation()
+    jest.spyOn(git, 'diffSummary').mockResolvedValue({
+      files: [{ file: 'index.ts', binary: false }]
+    } as DiffResult)
 
     await git.init()
     await git.addConfig('user.name', 'John Doe')

src/diff.ts

@@ -2,8 +2,8 @@ import { DiffNameStatus, simpleGit } from 'simple-git'
 
 export async function listChangedFiles(
   refs: {
-    base: { ref: string; sha: string }
-    head: { ref: string; sha: string }
+    base: string
+    head: string
   },
   git = simpleGit()
 ): Promise<string[]> {
@@ -13,8 +13,8 @@ export async function listChangedFiles(
   ]
   const { files } = await git.diffSummary([
     `--diff-filter=${statuses.join('')}`,
-    refs.base.ref,
-    refs.head.ref
+    refs.base,
+    refs.head
   ])
   return files.filter(({ binary }) => !binary).map(({ file }) => file)
 }

src/main.ts

@@ -45,7 +45,7 @@ export async function run(
     }
 
     if (isPullRequest(github.context.payload.pull_request)) {
-      const { base, head } = github.context.payload.pull_request
+      const { base } = github.context.payload.pull_request
       core.debug(`PR detected, preparing to compare base branch ${base.ref}`)
 
       let prevReport: string
@@ -94,7 +94,10 @@ export async function run(
       if (inputs.annotations) {
         await git.fetch('origin', base.ref, ['--depth=1'])
         const reportsDiff = await fs.readFile(diffJsonPath, 'utf8')
-        const changedFiles = await listChangedFiles({ base, head }, git)
+        const changedFiles = await listChangedFiles(
+          { base: 'FETCH_HEAD', head: 'HEAD' },
+          git
+        )
         const issues = filterRelevantIssues({
           currReport: JSON.parse(currReport),
           prevReport: JSON.parse(prevReport),