fix(github)!: change automerge priority order to prefer squash (#32016)

Changes the priority order so that squash merges are preferred over rebase merge and merge commits. Doing so allows GitHub to sign the resulting commit on the base branch.

BREAKING CHANGE: Renovate will now prefer squash merges over others in GitHub, if they are allowed.

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

@@ -532,7 +532,7 @@ describe('modules/platform/github/index', () => {
   }
 
   describe('initRepo', () => {
-    it('should rebase', async () => {
+    it('should squash', async () => {
       const scope = httpMock.scope(githubApiHost);
       initRepoMock(scope, 'some/repo');
       const config = await github.initRepo({ repository: 'some/repo' });
@@ -675,7 +675,7 @@ describe('modules/platform/github/index', () => {
       expect(config).toMatchSnapshot();
     });
 
-    it('should squash', async () => {
+    it('should merge', async () => {
       httpMock
         .scope(githubApiHost)
         .post(`/graphql`)
@@ -687,8 +687,8 @@ describe('modules/platform/github/index', () => {
               nameWithOwner: 'some/repo',
               hasIssuesEnabled: true,
               mergeCommitAllowed: true,
-              rebaseMergeAllowed: false,
-              squashMergeAllowed: true,
+              rebaseMergeAllowed: true,
+              squashMergeAllowed: false,
               defaultBranchRef: {
                 name: 'master',
                 target: {
@@ -704,7 +704,7 @@ describe('modules/platform/github/index', () => {
       expect(config).toMatchSnapshot();
     });
 
-    it('should merge', async () => {
+    it('should rebase', async () => {
       httpMock
         .scope(githubApiHost)
         .post(`/graphql`)
@@ -715,8 +715,8 @@ describe('modules/platform/github/index', () => {
               isArchived: false,
               nameWithOwner: 'some/repo',
               hasIssuesEnabled: true,
-              mergeCommitAllowed: true,
-              rebaseMergeAllowed: false,
+              mergeCommitAllowed: false,
+              rebaseMergeAllowed: true,
               squashMergeAllowed: false,
               defaultBranchRef: {
                 name: 'master',
@@ -2882,7 +2882,7 @@ describe('modules/platform/github/index', () => {
           },
           variables: {
             pullRequestId: 'abcd',
-            mergeMethod: 'REBASE',
+            mergeMethod: 'SQUASH',
           },
         },
       };
@@ -3510,7 +3510,7 @@ describe('modules/platform/github/index', () => {
         },
         variables: {
           pullRequestId: 'abcd',
-          mergeMethod: 'REBASE',
+          mergeMethod: 'SQUASH',
         },
       },
     };
@@ -3683,7 +3683,7 @@ describe('modules/platform/github/index', () => {
   });
 
   describe('mergePr(prNo) - autodetection', () => {
-    it('should try rebase first', async () => {
+    it('should try squash first', async () => {
       const scope = httpMock.scope(githubApiHost);
       initRepoMock(scope, 'some/repo');
       scope.put('/repos/some/repo/pulls/1235/merge').reply(200);
@@ -3702,12 +3702,12 @@ describe('modules/platform/github/index', () => {
       ).toBeTrue();
     });
 
-    it('should try squash after rebase', async () => {
+    it('should try merge after squash', async () => {
       const scope = httpMock.scope(githubApiHost);
       initRepoMock(scope, 'some/repo');
       scope
         .put('/repos/some/repo/pulls/1236/merge')
-        .reply(400, 'no rebasing allowed');
+        .reply(400, 'no squashing allowed');
       await github.initRepo({ repository: 'some/repo' });
       const pr = {
         number: 1236,
@@ -3723,15 +3723,15 @@ describe('modules/platform/github/index', () => {
       ).toBeFalse();
     });
 
-    it('should try merge after squash', async () => {
+    it('should try rebase after merge', async () => {
       const scope = httpMock.scope(githubApiHost);
       initRepoMock(scope, 'some/repo');
       scope
-        .put('/repos/some/repo/pulls/1237/merge')
-        .reply(405, 'no rebasing allowed')
         .put('/repos/some/repo/pulls/1237/merge')
         .reply(405, 'no squashing allowed')
         .put('/repos/some/repo/pulls/1237/merge')
+        .reply(405, 'no merging allowed')
+        .put('/repos/some/repo/pulls/1237/merge')
         .reply(200);
       await github.initRepo({ repository: 'some/repo' });
       const pr = {
@@ -3753,12 +3753,12 @@ describe('modules/platform/github/index', () => {
       initRepoMock(scope, 'some/repo');
       scope
         .put('/repos/some/repo/pulls/1237/merge')
-        .reply(405, 'no rebasing allowed')
-        .put('/repos/some/repo/pulls/1237/merge')
-        .replyWithError('no squashing allowed')
+        .reply(405, 'no squashing allowed')
         .put('/repos/some/repo/pulls/1237/merge')
         .replyWithError('no merging allowed')
         .put('/repos/some/repo/pulls/1237/merge')
+        .replyWithError('no rebasing allowed')
+        .put('/repos/some/repo/pulls/1237/merge')
         .replyWithError('never gonna give you up');
       await github.initRepo({ repository: 'some/repo' });
       const pr = {

lib/modules/platform/github/index.ts

@@ -553,12 +553,12 @@ export async function initRepo({
     // Base branch may be configured but defaultBranch is always fixed
     logger.debug(`${repository} default branch = ${config.defaultBranch}`);
     // GitHub allows administrators to block certain types of merge, so we need to check it
-    if (repo.rebaseMergeAllowed) {
-      config.mergeMethod = 'rebase';
-    } else if (repo.squashMergeAllowed) {
+    if (repo.squashMergeAllowed) {
       config.mergeMethod = 'squash';
     } else if (repo.mergeCommitAllowed) {
       config.mergeMethod = 'merge';
+    } else if (repo.rebaseMergeAllowed) {
+      config.mergeMethod = 'rebase';
     } else {
       // This happens if we don't have Administrator read access, it is not a critical error
       logger.debug('Could not find allowed merge methods for repo');
@@ -1910,25 +1910,25 @@ export async function mergePr({
     }
   }
   if (!automerged) {
-    // We need to guess the merge method and try squash -> rebase -> merge
-    options.body.merge_method = 'rebase';
+    // We need to guess the merge method and try squash -> merge -> rebase
+    options.body.merge_method = 'squash';
     try {
       logger.debug({ options, url }, `mergePr`);
       automergeResult = await githubApi.putJson(url, options);
     } catch (err1) {
-      logger.debug({ err: err1 }, `Failed to rebase merge PR`);
+      logger.debug({ err: err1 }, `Failed to squash merge PR`);
       try {
-        options.body.merge_method = 'squash';
+        options.body.merge_method = 'merge';
         logger.debug({ options, url }, `mergePr`);
         automergeResult = await githubApi.putJson(url, options);
       } catch (err2) {
-        logger.debug({ err: err2 }, `Failed to merge squash PR`);
+        logger.debug({ err: err2 }, `Failed to merge commit PR`);
         try {
-          options.body.merge_method = 'merge';
+          options.body.merge_method = 'rebase';
           logger.debug({ options, url }, `mergePr`);
           automergeResult = await githubApi.putJson(url, options);
         } catch (err3) {
-          logger.debug({ err: err3 }, `Failed to merge commit PR`);
+          logger.debug({ err: err3 }, `Failed to rebase merge PR`);
           logger.info({ pr: prNo }, 'All merge attempts failed');
           return false;
         }