feat: new branchNameStrict configuration flag

docs/usage/configuration-options.md

@@ -2911,3 +2911,7 @@ To disable the vulnerability alerts feature, set `enabled=false` in a `vulnerabi
   }
 }
 ```
+
+## strictBranchSlugify
+
+By default, Renovate does not use strict-mode when slugifying the branch name. To enforce strict-mode and prevent any special characters within the branch name, set this to `true`

lib/config/options/index.ts

@@ -2342,6 +2342,12 @@ const options: RenovateOptions[] = [
     default: false,
     supportedPlatforms: ['github'],
   },
+  {
+    name: 'strictBranchSlugify',
+    description: `Whether to be strict about the use of special characters in the branch name.`,
+    type: 'boolean',
+    default: false,
+  },
 ];
 
 export function getOptions(): RenovateOptions[] {

lib/config/types.ts

@@ -69,6 +69,7 @@ export interface RenovateSharedConfig {
   semanticCommits?: 'auto' | 'enabled' | 'disabled';
   semanticCommitScope?: string | null;
   semanticCommitType?: string;
+  strictBranchSlugify?: boolean;
   suppressNotifications?: string[];
   timezone?: string;
   unicodeEmoji?: boolean;

lib/workers/repository/updates/branch-name.spec.ts

@@ -230,14 +230,14 @@ describe('workers/repository/updates/branch-name', () => {
             groupName: 'invalid branch name.lock',
             group: { branchName: 'renovate/{{groupSlug}}' },
           },
-          expectedBranchName: 'renovate/invalid-branch-namelock',
+          expectedBranchName: 'renovate/invalid-branch-name',
         },
         {
           upgrade: {
             groupName: '.a-bad-  name:@.lock',
             group: { branchName: 'renovate/{{groupSlug}}' },
           },
-          expectedBranchName: 'renovate/a-bad-namelock',
+          expectedBranchName: 'renovate/a-bad-name-@',
         },
         {
           upgrade: { branchName: 'renovate/bad-branch-name1..' },
@@ -293,5 +293,35 @@ describe('workers/repository/updates/branch-name', () => {
         expect(fixture.upgrade.branchName).toEqual(fixture.expectedBranchName);
       });
     });
+
+    it('strict branch slugify enabled', () => {
+      const upgrade: RenovateConfig = {
+        strictBranchSlugify: true,
+        groupName: '[some] group name.#$%version',
+        group: {
+          branchName: '{{groupSlug}}-{{branchTopic}}',
+          branchTopic: 'grouptopic',
+        },
+      };
+      generateBranchName(upgrade);
+      expect(upgrade.branchName).toBe(
+        'some-group-namedollarpercentversion-grouptopic'
+      );
+    });
+
+    it('strict branch slugify disabled', () => {
+      const upgrade: RenovateConfig = {
+        strictBranchSlugify: false,
+        groupName: '[some] group name.#$%version',
+        group: {
+          branchName: '{{groupSlug}}-{{branchTopic}}',
+          branchTopic: 'grouptopic',
+        },
+      };
+      generateBranchName(upgrade);
+      expect(upgrade.branchName).toBe(
+        'some-group-name.dollarpercentversion-grouptopic'
+      );
+    });
   });
 });

lib/workers/repository/updates/branch-name.ts

@@ -43,7 +43,7 @@ export function generateBranchName(update: RenovateConfig): void {
     );
     update.groupSlug = slugify(update.groupSlug ?? update.groupName, {
       lower: true,
-      strict: true,
+      strict: update.strictBranchSlugify,
     });
     if (update.updateType === 'major' && update.separateMajorMinor) {
       if (update.separateMultipleMajor) {