fix: do not attempt to create pull request when no changes detected

src/github.ts

@@ -83,7 +83,7 @@
   token?: string;
   logger?: Logger;
   proxy?: ProxyOption;
   fetch?: any;
 }
 
 type CommitFilter = (commit: Commit) => boolean;
@@ -574,7 +574,7 @@
       }
     )) {
       // Paginate plugin doesn't have types for listing files on a commit
       const data = resp.data as any as {files: {filename: string}[]};
       for (const f of data.files || []) {
         if (f.filename) {
           files.push(f.filename);
@@ -1169,6 +1169,20 @@
         draft: !!options?.draft,
         labels: pullRequest.labels,
       });
+      if (prNumber === 0) {
+        this.logger.warn(
+          'no code changes detected, skipping pull request creation'
+        );
+        return {
+          headBranchName: pullRequest.headBranchName,
+          baseBranchName: targetBranch,
+          number: 0,
+          title: pullRequest.title,
+          body: pullRequest.body,
+          labels: pullRequest.labels,
+          files: [],
+        };
+      }
       return await this.getPullRequest(prNumber);
     }
   );

test/github.ts

@@ -1142,6 +1142,33 @@ describe('GitHub', () => {
     });
   });
 
+  describe('createPullRequest', () => {
+    it('should not call getPullRequest when no code changes detected', async () => {
+      const createPullRequestStub = sandbox
+        .stub(codeSuggester, 'createPullRequest')
+        .resolves(0);
+      const getPullRequestStub = sandbox.stub(github, 'getPullRequest');
+
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      const pullRequest = await (github as any).createPullRequest(
+        {
+          headBranchName: 'release-please--branches--main',
+          baseBranchName: 'main',
+          title: 'Release v1.0.0',
+          body: 'Release body',
+          labels: ['release-please'],
+        },
+        'main',
+        'commit message',
+        []
+      );
+
+      expect(pullRequest.number).to.eql(0);
+      sinon.assert.calledOnce(createPullRequestStub);
+      sinon.assert.notCalled(getPullRequestStub);
+    });
+  });
+
   describe('buildChangeSet', () => {
     it('should merge updates for the same file', async () => {
       const manifestPath = '.release-please-manifest.json';