test: add coverage for auto merge feature

e2e/e2e.spec.ts

@@ -468,8 +468,8 @@ describe("e2e tests", () => {
     );
 
     // Pull request was created with the corrects params
-    expect(fakeGitHub.pullRequestHandler).toHaveBeenCalledTimes(1);
-    const request = fakeGitHub.pullRequestHandler.mock
+    expect(fakeGitHub.createPullRequestHandler).toHaveBeenCalledTimes(1);
+    const request = fakeGitHub.createPullRequestHandler.mock
       .calls[0][0] as CompletedRequest;
     expect(request.path).toEqual(
       expect.stringMatching(/bazelbuild\/bazel-central-registry/)
@@ -491,6 +491,22 @@ describe("e2e tests", () => {
         `https://github.com/${testOrg}/${repo}/releases/tag/${tag}`
       )
     );
+
+    // Pull request was updated to enable auto merge
+    expect(fakeGitHub.updatePullRequestHandler).toHaveBeenCalledTimes(1);
+    const updateRequest = fakeGitHub.updatePullRequestHandler.mock
+      .calls[0][0] as CompletedRequest;
+    expect(updateRequest.path).toEqual(
+      expect.stringMatching(
+        /repos\/bazelbuild\/bazel-central-registry\/pulls\/\d+/
+      )
+    );
+    const updateBody = (await updateRequest.body.getJson()) as any;
+    expect(updateBody).toEqual(
+      expect.objectContaining({
+        allow_auto_merge: true,
+      })
+    );
   });
 
   test("happy path with multiple modules", async () => {
@@ -536,8 +552,8 @@ describe("e2e tests", () => {
     expect(messages.length).toEqual(0);
 
     // One pull requests was created with the corrects params
-    expect(fakeGitHub.pullRequestHandler).toHaveBeenCalledTimes(1);
-    let request = fakeGitHub.pullRequestHandler.mock
+    expect(fakeGitHub.createPullRequestHandler).toHaveBeenCalledTimes(1);
+    let request = fakeGitHub.createPullRequestHandler.mock
       .calls[0][0] as CompletedRequest;
     expect(request.path).toEqual(
       expect.stringMatching(/bazelbuild\/bazel-central-registry/)
@@ -644,8 +660,8 @@ describe("e2e tests", () => {
     expect(response.status).toEqual(200);
 
     // Pull request points to releaser's BCR fork
-    expect(fakeGitHub.pullRequestHandler).toHaveBeenCalled();
-    const request = fakeGitHub.pullRequestHandler.mock
+    expect(fakeGitHub.createPullRequestHandler).toHaveBeenCalled();
+    const request = fakeGitHub.createPullRequestHandler.mock
       .calls[0][0] as CompletedRequest;
     const body = (await request.body.getJson()) as any;
     expect(body).toEqual(

e2e/stubs/fake-github.ts

@@ -1,6 +1,7 @@
 import { User } from "@octokit/webhooks-types";
 import { randomUUID } from "crypto";
 import * as mockttp from "mockttp";
+import { randomInt } from "node:crypto";
 import url from "node:url";
 import { StubbedServer } from "./stubbed-server";
 
@@ -18,7 +19,8 @@ export class FakeGitHub implements StubbedServer {
     { owner: string; repo: string; sourceOwner?: string; sourceRepo?: string }
   >();
 
-  public readonly pullRequestHandler = jest.fn();
+  public readonly createPullRequestHandler = jest.fn();
+  public readonly updatePullRequestHandler = jest.fn();
   public readonly installationTokenHandler = jest.fn();
 
   public constructor() {
@@ -38,14 +40,16 @@ export class FakeGitHub implements StubbedServer {
       this.setupGetOwnedReposHandler(),
       this.setupGetRepoHandler(),
       this.setupCreatePullHandler(),
+      this.setupUpdatePullHandler(),
       this.setupAppHandler(),
     ]);
   }
 
   public async reset(): Promise<void> {
     this.server.reset();
     this.clearMockedData();
-    this.pullRequestHandler.mockReset();
+    this.createPullRequestHandler.mockReset();
+    this.updatePullRequestHandler.mockReset();
     this.installationTokenHandler.mockReset();
     await this.setupHandlers();
   }
@@ -262,16 +266,31 @@ export class FakeGitHub implements StubbedServer {
   }
 
   private async setupCreatePullHandler(): Promise<void> {
-    this.pullRequestHandler.mockImplementation((request) => {
+    this.createPullRequestHandler.mockImplementation((request) => {
       return {
         statusCode: 201,
-        body: "{}",
+        json: {
+          number: randomInt(100),
+        },
       };
     });
 
     await this.server
       .forPost("/repos/bazelbuild/bazel-central-registry/pulls")
-      .thenCallback((request) => this.pullRequestHandler(request));
+      .thenCallback((request) => this.createPullRequestHandler(request));
+  }
+
+  private async setupUpdatePullHandler(): Promise<void> {
+    this.updatePullRequestHandler.mockImplementation((request) => {
+      return {
+        statusCode: 200,
+        json: {},
+      };
+    });
+
+    await this.server
+      .forPatch(/\/repos\/bazelbuild\/bazel-central-registry\/pulls\/\d+$/)
+      .thenCallback((request) => this.updatePullRequestHandler(request));
   }
 
   private async setupAppHandler(): Promise<void> {