Add support for placeholder merge requests

Author: mschoettle

README.md

@@ -206,8 +206,18 @@ Set to `true` (default) to enable using the [GitHub preview API for importing is
 
 ### usePlaceholderIssuesForMissingIssues
 
+NOTE: This setting requires `usePlaceholderIssuesForMissingMergeRequests` to be set to `false` (default).
+
 If this is set to `true` (default) then the migration process will automatically create empty dummy issues for every 'missing' GitLab issue (if you deleted a GitLab issue for example). Those issues will be closed on Github and they ensure that the issue ids stay the same on both GitLab and Github.
 
+### usePlaceholderIssuesForMissingMergeRequests
+
+NOTE: GitLab has distinct numbers for issues and merge requests whereas GitHub treats pull requests as issues.
+Only use this setting if your GitLab repository does not have issues or you do not intend on migrating them.
+This setting therefore requires `usePlaceholderIssuesForMissingIssues` to be set to `false`.
+
+If this is set to `true` then the migration process will automatically create empty dummy issues for every 'missing' GitLab merge request (if you deleted a GitLab merge request for example). Those issues will be closed on Github and they ensure that the issue ids stay the same on both GitLab and Github.
+
 #### usePlaceholderMilestonesForMissingMilestones
 
 If this is set to `true` (default) then the migration process will automatically create empty dummy milestones for every 'missing' GitLab milestone (if you deleted a GitLab milestone for example). Those milestones will be closed on Github and they ensure that the milestone ids stay the same on both GitLab and Github.

sample_settings.ts

@@ -49,6 +49,7 @@ export default {
   useIssueImportAPI: true,
   usePlaceholderMilestonesForMissingMilestones: true,
   usePlaceholderIssuesForMissingIssues: true,
+  usePlaceholderIssuesForMissingMergeRequests: false,
   useReplacementIssuesForCreationFails: true,
   useIssuesForAllMergeRequests: false,
   filterByLabel: undefined,

src/githubHelper.ts

@@ -900,6 +900,15 @@ export class GithubHelper {
   async createPullRequestAndComments(
     mergeRequest: GitLabMergeRequest
   ): Promise<void> {
+    // Use the issue creation for placeholder issues
+    if (mergeRequest.isPlaceholder) {
+      let issue = mergeRequest as unknown;
+      await this.createIssueAndComments(issue as GitLabIssue);
+      console.log(`Created placeholder issue for placeholder merge request #${mergeRequest.iid}`);
+
+      return;
+    }
+
     let pullRequestData = await this.createPullRequest(mergeRequest);
 
     // createPullRequest() returns an issue number if a PR could not be created and

src/index.ts

@@ -4,7 +4,7 @@ import {
   SimpleLabel,
   SimpleMilestone,
 } from './githubHelper';
-import { GitlabHelper, GitLabIssue, GitLabMilestone } from './gitlabHelper';
+import { GitlabHelper, GitLabIssue, GitLabMergeRequest, GitLabMilestone } from './gitlabHelper';
 import settings from '../settings';
 
 import { Octokit as GitHubApi } from '@octokit/rest';
@@ -156,6 +156,23 @@ function createPlaceholderIssue(expectedIdx: number): Partial<GitLabIssue> {
   };
 }
 
+/**
+ * Creates dummy data for a placeholder issue
+ *
+ * @param expectedIdx Number of the GitLab issue
+ * @returns Data for the issue
+ */
+function createPlaceholderMergeRequest(expectedIdx: number): Partial<GitLabMergeRequest> {
+  return {
+    iid: expectedIdx,
+    title: `[PLACEHOLDER] - for merge request #${expectedIdx}`,
+    description:
+      'This is to ensure that merge request numbers in GitLab and GitHub are the same',
+    state: 'closed',
+    isPlaceholder: true,
+  };
+}
+
 // ----------------------------------------------------------------------------
 
 /**
@@ -549,6 +566,25 @@ async function transferMergeRequests() {
   // Issues are sometimes created from Gitlab merge requests. Avoid creating duplicates.
   let githubIssues = await githubHelper.getAllGithubIssues();
 
+  if (settings.usePlaceholderIssuesForMissingMergeRequests) {
+    for (let i = 0; i < mergeRequests.length; i++) {
+      // GitLab issue internal Id (iid)
+      let expectedIdx = i + 1;
+
+      // is there a gap in the GitLab merge requests?
+      // Create placeholder issues so that new GitHub issues will have the same
+      // issue number as in GitLab. If a placeholder is used it is because there
+      // was a gap in GitLab merge requests -- likely caused by a deleted GitLab merge request.
+      if (mergeRequests[i].iid !== expectedIdx) {
+        mergeRequests.splice(i, 0, createPlaceholderMergeRequest(expectedIdx) as GitLabMergeRequest); // HACK: remove type coercion
+        counters.nrOfPlaceholderIssues++;
+        console.log(
+          `Added placeholder issue for GitLab merge request #${expectedIdx}.`
+        );
+      }
+    }
+  }
+
   console.log(
     'Transferring ' + mergeRequests.length.toString() + ' merge requests'
   );
@@ -568,11 +604,17 @@ async function transferMergeRequests() {
     let githubIssue = githubIssues.find(
       // allow for issues titled "Original Issue Name - [merged|closed]"
       i => {
-        // regex needs escaping in case merge request title contains special characters
-        const regex = new RegExp(escapeRegExp(mr.title.trim()) + ' - \\[(merged|closed)\\]');
-        return regex.test(i.title.trim()) && i.body.includes(mr.web_url);
+        if (!mr.isPlaceholder) {
+          // regex needs escaping in case merge request title contains special characters
+          const regex = new RegExp(escapeRegExp(mr.title.trim()) + ' - \\[(merged|closed)\\]');
+          return regex.test(i.title.trim()) && i.body.includes(mr.web_url);
+        }
+        else {
+          return i.title.trim() === mr.title.trim();
+        }
       }
     );
+
     if (!githubRequest && !githubIssue) {
       if (settings.skipMergeRequestStates.includes(mr.state)) {
         console.log(

src/settings.ts

@@ -24,6 +24,7 @@ export default interface Settings {
   useIssueImportAPI: boolean;
   usePlaceholderMilestonesForMissingMilestones: boolean;
   usePlaceholderIssuesForMissingIssues: boolean;
+  usePlaceholderIssuesForMissingMergeRequests: boolean;
   useReplacementIssuesForCreationFails: boolean;
   useIssuesForAllMergeRequests: boolean;
   filterByLabel?: string;