feat: support merging in gitlab

Implement accept merge request api.

Relates to #166

Author: KnisterPeter

src/provider/gitlab/api.ts

@@ -14,6 +14,8 @@ export interface GitLab {
   getMergeRequest(id: string, mr_iid: number): Promise<GitLabResponse<MergeRequest>>;
   createMergeRequest(id: string, body: CreateMergeRequestBody): Promise<GitLabResponse<MergeRequest>>;
   updateMergeRequest(id: string, mr_iid: number, body: UpdateMergeRequestBody): Promise<GitLabResponse<MergeRequest>>;
+  acceptMergeRequest(id: string, mr_iid: number, body: AcceptMergeRequestBody)
+    : Promise<GitLabResponse<AcceptMergeRequestResponse>>;
   getProjectIssues(id: string, body: ProjectIssuesBody): Promise<GitLabResponse<Issue[]>>;
   searchUser(parameters?: SearchUsersParameters): Promise<GitLabResponse<UserResponse[]>>;
 }
@@ -24,6 +26,16 @@ export interface GitLabResponse<T> {
   body: T;
 }
 
+export interface AcceptMergeRequestBody {
+  should_remove_source_branch?: boolean;
+}
+
+export interface AcceptMergeRequestResponse {
+  title: string;
+  state: 'merged';
+  sha: string;
+}
+
 export interface SearchUsersParameters {
   username?: string;
 }
@@ -190,6 +202,9 @@ namespace impl {
     @Put('/projects/:id/merge_requests/:merge_request_iid')
     public updateMergeRequest(): any {/* */}
 
+    @Put('/projects/:id/merge_requests/:merge_request_iid/merge')
+    public acceptMergeRequest(): any {/* */}
+
     @Get('/projects/:id/issues')
     public getProjectIssues(): any {/* */}
 

src/provider/gitlab/merge-request.ts

@@ -1,3 +1,4 @@
+import { getConfiguration } from '../../helper';
 import { Response } from '../client';
 import {
   PullRequest,
@@ -102,7 +103,20 @@ export class GitLabMergeRequest implements PullRequest {
   }
 
   public async merge(_body: MergeBody): Promise<Response<MergeResult>> {
-    throw new Error('Method not implemented.');
+    const response = await this.client.acceptMergeRequest(
+      encodeURIComponent(this.repository.pathWithNamespace),
+      this.mergeRequest.iid,
+      {
+        should_remove_source_branch: getConfiguration('gitlab').removeSourceBranch
+      }
+    );
+    return {
+      body: {
+        message: response.body.title,
+        merged: response.body.state === 'merged',
+        sha: response.body.sha
+      }
+    };
   }
 
   public async assign(assignees: GitLabUser[]): Promise<void> {