feat: support pull requests with more than 300 changed files

__tests__/utils/diff.test.ts

@@ -1,5 +1,5 @@
 import {test, expect} from 'vitest'
-import {parseGitDiff} from '../../src/utils/diff'
+import {parseGitDiff, parsePatch} from '../../src/utils/diff'
 import {getFixturePath} from '../fixtures/util'
 import * as fs from 'fs'
 
@@ -10,3 +10,40 @@ test('should parse Git diff', async function () {
 
   expect(output).toMatchSnapshot()
 })
+
+test('parsePatch should return empty array for empty patch', () => {
+  expect(parsePatch('')).toEqual([])
+})
+
+test('parsePatch should parse single hunk patch', () => {
+  const patch = `@@ -0,0 +1,3 @@
++line 1
++line 2
++line 3`
+  expect(parsePatch(patch)).toEqual([1, 2, 3])
+})
+
+test('parsePatch should parse patch with context and deletions', () => {
+  const patch = `@@ -1,5 +1,6 @@
+ unchanged line 1
+-deleted line
++added line 1
++added line 2
+ unchanged line 2
+ unchanged line 3`
+  // Line 2 and 3 are the added lines (after unchanged line 1 at position 1)
+  expect(parsePatch(patch)).toEqual([2, 3])
+})
+
+test('parsePatch should parse patch with multiple hunks', () => {
+  const patch = `@@ -1,3 +1,4 @@
+ line 1
++new line 2
+ line 3
+ line 4
+@@ -10,3 +11,4 @@
+ line 11
++new line 12
+ line 13`
+  expect(parsePatch(patch)).toEqual([2, 12])
+})

src/utils/diff.ts

@@ -4,6 +4,35 @@ interface FileDiff {
   deletedLines: number[]
 }
 
+/**
+ * Parse a single file's patch (from GitHub's listFiles API) to extract added line numbers.
+ * The patch format contains only hunk headers (@@) and changes, not the full diff header.
+ */
+export function parsePatch(patch: string): number[] {
+  const addedLines: number[] = []
+  const lines = patch.split('\n')
+  let additionCurrentLineNumber = 0
+  let seenHeaderLine = false
+
+  for (const line of lines) {
+    if (line.startsWith('@@')) {
+      seenHeaderLine = true
+      const lineInfo = getLineInfoFromHeaderLine(line)
+      additionCurrentLineNumber = lineInfo.additionStartingLineNumber
+    } else if (line.startsWith('+') && seenHeaderLine) {
+      addedLines.push(additionCurrentLineNumber)
+      additionCurrentLineNumber++
+    } else if (line.startsWith('-') && seenHeaderLine) {
+      // Deleted line - don't increment addition line number
+    } else if (seenHeaderLine) {
+      // Context line
+      additionCurrentLineNumber++
+    }
+  }
+
+  return addedLines
+}
+
 export function parseGitDiff(diffOutput: string): FileDiff[] {
   const fileDiffs: FileDiff[] = []
   const lines = diffOutput.split('\n')

src/utils/github.ts

@@ -1,5 +1,5 @@
 import * as core from '@actions/core'
-import * as diff from './diff'
+import {parsePatch} from './diff'
 import * as github from '@actions/github'
 import {
   CoverageFile,
@@ -28,17 +28,27 @@ export class GithubUtil {
 
   async getPullRequestDiff(): Promise<PullRequestFiles> {
     const pull_number = github.context.issue.number
-    const response = await this.client.rest.pulls.get({
-      ...github.context.repo,
-      pull_number,
-      mediaType: {
-        format: 'diff'
-      }
-    })
-    const fileLines = diff.parseGitDiff(response.data as unknown as string)
     const prFiles: PullRequestFiles = {}
-    for (const item of fileLines) {
-      prFiles[item.filename] = coalesceLineNumbers(item.addedLines)
+
+    // Use paginated listFiles API to handle PRs with more than 300 files
+    const iterator = this.client.paginate.iterator(
+      this.client.rest.pulls.listFiles,
+      {
+        ...github.context.repo,
+        pull_number,
+        per_page: 100
+      }
+    )
+
+    for await (const response of iterator) {
+      for (const file of response.data) {
+        if (file.patch) {
+          const addedLines = parsePatch(file.patch)
+          if (addedLines.length > 0) {
+            prFiles[file.filename] = coalesceLineNumbers(addedLines)
+          }
+        }
+      }
     }
 
     return prFiles