fix(github): Remote branch existence check

lib/modules/platform/github/branch.spec.ts

@@ -0,0 +1,57 @@
+import * as httpMock from '../../../../test/http-mock';
+import { GithubHttp } from '../../../util/http/github';
+import { remoteBranchExists } from './branch';
+
+describe('modules/platform/github/branch', () => {
+  const http = new GithubHttp();
+
+  it('should return true if the branch exists', async () => {
+    httpMock
+      .scope('https://api.github.com')
+      .head('/repos/my/repo/git/refs/heads/renovate/foobar/')
+      .reply(404)
+      .head('/repos/my/repo/git/refs/heads/renovate/foobar')
+      .reply(200, { ref: 'renovate/foobar' });
+
+    const result = await remoteBranchExists(http, 'my/repo', 'renovate/foobar');
+
+    expect(result).toBe(true);
+  });
+
+  it('should return false if the branch does not exist', async () => {
+    httpMock
+      .scope('https://api.github.com')
+      .head('/repos/my/repo/git/refs/heads/renovate/foobar/')
+      .reply(404)
+      .head('/repos/my/repo/git/refs/heads/renovate/foobar')
+      .reply(404);
+
+    const result = await remoteBranchExists(http, 'my/repo', 'renovate/foobar');
+
+    expect(result).toBe(false);
+  });
+
+  it('should throw an error for nested branches', async () => {
+    httpMock
+      .scope('https://api.github.com')
+      .head('/repos/my/repo/git/refs/heads/renovate/foobar/')
+      .reply(200);
+
+    await expect(
+      remoteBranchExists(http, 'my/repo', 'renovate/foobar')
+    ).rejects.toThrow(
+      `Trying to create a branch 'renovate/foobar' while it's the part of nested branch`
+    );
+  });
+
+  it('should throw an error if the request fails for any other reason', async () => {
+    httpMock
+      .scope('https://api.github.com')
+      .head('/repos/my/repo/git/refs/heads/renovate/foobar/')
+      .reply(500, { message: 'Something went wrong' });
+
+    await expect(
+      remoteBranchExists(http, 'my/repo', 'renovate/foobar')
+    ).rejects.toThrow('external-host-error');
+  });
+});

lib/modules/platform/github/branch.ts

@@ -0,0 +1,38 @@
+import { Http, HttpError } from '../../../util/http';
+import { Result } from '../../../util/result';
+
+function headRef(
+  http: Http,
+  repo: string,
+  branchName: string
+): Promise<boolean> {
+  return Result.wrap(
+    http.headJson(`/repos/${repo}/git/refs/heads/${branchName}`, {
+      memCache: false,
+    })
+  )
+    .transform(() => true)
+    .catch((err) => {
+      if (err instanceof HttpError && err.response?.statusCode === 404) {
+        return Result.ok(false);
+      }
+
+      return Result.err(err);
+    })
+    .unwrapOrThrow();
+}
+
+export async function remoteBranchExists(
+  http: Http,
+  repo: string,
+  branchName: string
+): Promise<boolean> {
+  const refNested = `${branchName}/`;
+  const isNested = await headRef(http, repo, refNested);
+  if (isNested) {
+    const message = `Trying to create a branch '${branchName}' while it's the part of nested branch`;
+    throw new Error(message);
+  }
+
+  return headRef(http, repo, branchName);
+}

lib/modules/platform/github/index.spec.ts

@@ -16,6 +16,7 @@ import { setBaseUrl } from '../../../util/http/github';
 import { toBase64 } from '../../../util/string';
 import { hashBody } from '../pr-body';
 import type { CreatePRConfig, RepoParams, UpdatePrConfig } from '../types';
+import * as branch from './branch';
 import type { ApiPageCache, GhRestPr } from './types';
 import * as github from '.';
 
@@ -939,8 +940,6 @@ describe('modules/platform/github/index', () => {
         ])
         .head('/repos/some/repo/git/commits/123')
         .reply(200)
-        .head('/repos/some/repo/git/refs/heads/somebranch')
-        .reply(404)
         .post('/repos/some/repo/git/refs')
         .reply(201)
         .patch('/repos/some/repo/pulls/91')
@@ -953,6 +952,7 @@ describe('modules/platform/github/index', () => {
           updated_at: '01-09-2022',
         });
       await github.initRepo({ repository: 'some/repo' });
+      jest.spyOn(branch, 'remoteBranchExists').mockResolvedValueOnce(false);
 
       const pr = await github.getBranchPr('somebranch');
       const pr2 = await github.getBranchPr('somebranch');
@@ -1036,12 +1036,11 @@ describe('modules/platform/github/index', () => {
         ])
         .head('/repos/some/repo/git/commits/123')
         .reply(200)
-        .head('/repos/some/repo/git/refs/heads/somebranch')
-        .reply(404)
         .post('/repos/some/repo/git/refs')
         .reply(201)
         .patch('/repos/some/repo/pulls/91')
         .reply(422);
+      jest.spyOn(branch, 'remoteBranchExists').mockResolvedValueOnce(false);
 
       await github.initRepo({ repository: 'some/repo' });
       const pr = await github.getBranchPr('somebranch');
@@ -1069,9 +1068,8 @@ describe('modules/platform/github/index', () => {
           },
         ])
         .head('/repos/some/repo/git/commits/123')
-        .reply(200)
-        .head('/repos/some/repo/git/refs/heads/somebranch')
-        .reply(422);
+        .reply(200);
+      jest.spyOn(branch, 'remoteBranchExists').mockRejectedValueOnce('oops');
 
       await github.initRepo({ repository: 'some/repo' });
       const pr = await github.getBranchPr('somebranch');
@@ -3387,10 +3385,9 @@ describe('modules/platform/github/index', () => {
         .reply(200, { sha: '222' })
         .head('/repos/some/repo/git/commits/222')
         .reply(200)
-        .head('/repos/some/repo/git/refs/heads/foo/bar')
-        .reply(404)
         .post('/repos/some/repo/git/refs')
         .reply(200);
+      jest.spyOn(branch, 'remoteBranchExists').mockResolvedValueOnce(false);
 
       const res = await github.commitFiles({
         branchName: 'foo/bar',
@@ -3417,10 +3414,9 @@ describe('modules/platform/github/index', () => {
         .reply(200, { sha: '222' })
         .head('/repos/some/repo/git/commits/222')
         .reply(200)
-        .head('/repos/some/repo/git/refs/heads/foo/bar')
-        .reply(200)
         .patch('/repos/some/repo/git/refs/heads/foo/bar')
         .reply(200);
+      jest.spyOn(branch, 'remoteBranchExists').mockResolvedValueOnce(true);
 
       const res = await github.commitFiles({
         branchName: 'foo/bar',
@@ -3447,12 +3443,11 @@ describe('modules/platform/github/index', () => {
         .reply(200, { sha: '222' })
         .head('/repos/some/repo/git/commits/222')
         .reply(200)
-        .head('/repos/some/repo/git/refs/heads/foo/bar')
-        .reply(200)
         .patch('/repos/some/repo/git/refs/heads/foo/bar')
         .reply(422)
         .post('/repos/some/repo/git/refs')
         .reply(200);
+      jest.spyOn(branch, 'remoteBranchExists').mockResolvedValueOnce(true);
 
       const res = await github.commitFiles({
         branchName: 'foo/bar',
@@ -3479,10 +3474,9 @@ describe('modules/platform/github/index', () => {
         .reply(200, { sha: '222' })
         .head('/repos/some/repo/git/commits/222')
         .reply(200)
-        .head('/repos/some/repo/git/refs/heads/foo/bar')
-        .reply(200)
         .patch('/repos/some/repo/git/refs/heads/foo/bar')
         .reply(404);
+      jest.spyOn(branch, 'remoteBranchExists').mockResolvedValueOnce(true);
 
       const res = await github.commitFiles({
         branchName: 'foo/bar',

lib/modules/platform/github/index.ts

@@ -61,6 +61,7 @@ import type {
 } from '../types';
 import { repoFingerprint } from '../util';
 import { smartTruncate } from '../utils/pr-body';
+import { remoteBranchExists } from './branch';
 import { coerceRestPr } from './common';
 import {
   enableAutoMergeMutation,
@@ -760,25 +761,21 @@ export async function findPr({
 const REOPEN_THRESHOLD_MILLIS = 1000 * 60 * 60 * 24 * 7;
 
 async function ensureBranchSha(branchName: string, sha: string): Promise<void> {
+  const repository = config.repository!;
   try {
-    const commitUrl = `/repos/${config.repository}/git/commits/${sha}`;
+    const commitUrl = `/repos/${repository}/git/commits/${sha}`;
     await githubApi.head(commitUrl, { memCache: false });
   } catch (err) {
     logger.error({ err, sha, branchName }, 'Commit not found');
     throw err;
   }
 
   const refUrl = `/repos/${config.repository}/git/refs/heads/${branchName}`;
-  let branchExists = false;
-  let branchResult: undefined | HttpResponse<string>;
-  try {
-    branchResult = await githubApi.head(refUrl, { memCache: false });
-    branchExists = true;
-  } catch (err) {
-    if (err.statusCode !== 404) {
-      throw err;
-    }
-  }
+  const branchExists = await remoteBranchExists(
+    githubApi,
+    repository,
+    branchName
+  );
 
   if (branchExists) {
     try {
@@ -787,17 +784,17 @@ async function ensureBranchSha(branchName: string, sha: string): Promise<void> {
     } catch (err) {
       if (err.err?.response?.statusCode === 422) {
         logger.debug(
-          { branchResult, err },
+          { err },
           'Branch update failed due to reference not existing - will try to create'
         );
       } else {
-        logger.warn({ refUrl, err, branchResult }, 'Error updating branch');
+        logger.warn({ refUrl, err }, 'Error updating branch');
         throw err;
       }
     }
   }
 
-  await githubApi.postJson(`/repos/${config.repository}/git/refs`, {
+  await githubApi.postJson(`/repos/${repository}/git/refs`, {
     body: { sha, ref: `refs/heads/${branchName}` },
   });
 }