feat(web): resolve walkthrough diffs for GitLab merge requests

packages/web/server/lib/walkthrough/pull-request.test.js

@@ -2,10 +2,14 @@ import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 
 vi.mock('../github/octokit.js', () => ({ getOctokitOrNull: vi.fn() }));
 vi.mock('../github/repo/index.js', () => ({ resolveGitHubRepoFromDirectory: vi.fn() }));
+vi.mock('../gitlab/client.js', () => ({ getGitLabClientOrNull: vi.fn() }));
+vi.mock('../gitlab/repo.js', () => ({ resolveGitLabRepoFromDirectory: vi.fn() }));
 
 const { getPullRequestDiff } = await import('./pull-request.js');
 const { getOctokitOrNull } = await import('../github/octokit.js');
 const { resolveGitHubRepoFromDirectory } = await import('../github/repo/index.js');
+const { getGitLabClientOrNull } = await import('../gitlab/client.js');
+const { resolveGitLabRepoFromDirectory } = await import('../gitlab/repo.js');
 
 const PATCH = `diff --git a/src/a.ts b/src/a.ts
 --- a/src/a.ts
@@ -14,6 +18,28 @@ const PATCH = `diff --git a/src/a.ts b/src/a.ts
 +const added = true;
 `;
 
+const GITLAB_DIFF_ONE = `diff --git a/a.txt b/a.txt
+--- a/a.txt
++++ b/a.txt
+@@ -1,1 +1,2 @@
++hello
+`;
+
+const GITLAB_DIFF_TWO = `diff --git a/b.txt b/b.txt
+--- a/b.txt
++++ b/b.txt
+@@ -1 +1,2 @@
++world
+`;
+
+const GITLAB_REPO = {
+  namespace: 'acme',
+  project: 'widgets',
+  host: 'gitlab.com',
+  baseUrl: 'https://gitlab.com',
+  url: 'https://gitlab.com/acme/widgets',
+};
+
 describe('getPullRequestDiff', () => {
   let request;
 
@@ -27,6 +53,10 @@ describe('getPullRequestDiff', () => {
       repo: { owner: 'openchamber', repo: 'openchamber' },
       remoteUrl: 'git@github.com:openchamber/openchamber.git',
     });
+    // Default to a non-GitLab directory so the GitHub cases keep routing to
+    // the GitHub path.
+    resolveGitLabRepoFromDirectory.mockResolvedValue({ repo: null, remoteUrl: null });
+    getGitLabClientOrNull.mockReturnValue(null);
   });
 
   afterEach(() => {
@@ -74,4 +104,81 @@ describe('getPullRequestDiff', () => {
       statusCode: 404,
     });
   });
+
+  describe('with a GitLab repository', () => {
+    let mergeRequestDiffs;
+
+    beforeEach(() => {
+      mergeRequestDiffs = vi.fn().mockResolvedValue({
+        status: 200,
+        data: [{ diff: GITLAB_DIFF_ONE }],
+        page: { page: 1, next: null, total: 1, hasMore: false },
+      });
+      getGitLabClientOrNull.mockReturnValue({ mergeRequestDiffs });
+      resolveGitLabRepoFromDirectory.mockResolvedValue({
+        repo: GITLAB_REPO,
+        remoteUrl: 'git@gitlab.com:acme/widgets.git',
+      });
+    });
+
+    it('concatenates merge request diffs across pages into a single patch', async () => {
+      mergeRequestDiffs
+        .mockResolvedValueOnce({
+          status: 200,
+          data: [{ diff: GITLAB_DIFF_ONE }],
+          page: { page: 1, next: 2, total: 2, hasMore: true },
+        })
+        .mockResolvedValueOnce({
+          status: 200,
+          data: [{ diff: GITLAB_DIFF_TWO }],
+          page: { page: 2, next: null, total: 2, hasMore: false },
+        });
+
+      const result = await getPullRequestDiff('/repo', 7);
+
+      expect(result.patch).toBe(`${GITLAB_DIFF_ONE}\n${GITLAB_DIFF_TWO}`);
+      expect(result.meta).toEqual({ namespace: 'acme', project: 'widgets', number: 7 });
+      // The unencoded namespace/project path is passed to the client, which
+      // URL-encodes it internally.
+      expect(mergeRequestDiffs).toHaveBeenCalledTimes(2);
+      expect(mergeRequestDiffs).toHaveBeenNthCalledWith(1, 'acme/widgets', 7, { per_page: 100, page: 1 });
+      expect(mergeRequestDiffs).toHaveBeenNthCalledWith(2, 'acme/widgets', 7, { per_page: 100, page: 2 });
+    });
+
+    it('asks the user to connect GitLab before fetching diffs', async () => {
+      getGitLabClientOrNull.mockReturnValue(null);
+
+      await expect(getPullRequestDiff('/repo', 7)).rejects.toMatchObject({
+        code: 'gitlab-not-connected',
+        statusCode: 401,
+      });
+      expect(mergeRequestDiffs).not.toHaveBeenCalled();
+    });
+
+    it('treats an MR with no diff as missing rather than an empty review', async () => {
+      mergeRequestDiffs.mockResolvedValue({
+        status: 200,
+        data: [{ diff: '   ' }],
+        page: { page: 1, next: null, total: 1, hasMore: false },
+      });
+
+      await expect(getPullRequestDiff('/repo', 7)).rejects.toMatchObject({
+        code: 'empty-diff',
+        statusCode: 404,
+      });
+    });
+
+    it('reports a GitLab repo without namespace or project as having no remote', async () => {
+      resolveGitLabRepoFromDirectory.mockResolvedValue({
+        repo: { namespace: '', project: '' },
+        remoteUrl: 'git@gitlab.com:acme/widgets.git',
+      });
+
+      await expect(getPullRequestDiff('/repo', 7)).rejects.toMatchObject({
+        code: 'no-gitlab-remote',
+        statusCode: 400,
+      });
+      expect(mergeRequestDiffs).not.toHaveBeenCalled();
+    });
+  });
 });