Merge branch 'sh-fix-paste-markdown-from-diff' into 'master'

Avoid copying diffs as Markdown tables

Closes #213033

See merge request gitlab-org/gitlab!30572

app/assets/javascripts/behaviors/markdown/paste_markdown_table.js

@@ -47,7 +47,8 @@ export default class PasteMarkdownTable {
 
     const htmlData = this.data.getData('text/html');
     this.doc = new DOMParser().parseFromString(htmlData, 'text/html');
-    const tables = this.doc.querySelectorAll('table');
+    // Avoid formatting lines that were copied from a diff
+    const tables = this.doc.querySelectorAll('table:not(.diff-wrap-lines)');
 
     // We're only looking for exactly one table. If there happens to be
     // multiple tables, it's possible an application copied data into

changelogs/unreleased/sh-fix-paste-markdown-from-diff.yml

+---
+title: Avoid copying diffs as Markdown tables
+merge_request: 30572
+author:
+type: fixed

spec/frontend/behaviors/markdown/paste_markdown_table_spec.js

@@ -57,6 +57,18 @@ describe('PasteMarkdownTable', () => {
 
       expect(new PasteMarkdownTable(data).isTable()).toBe(false);
     });
+
+    it('returns false when the table copy comes from a diff', () => {
+      data.types = ['text/html', 'text/plain'];
+      data.getData = jest.fn().mockImplementation(mimeType => {
+        if (mimeType === 'text/html') {
+          return '<table class="diff-wrap-lines"><tr><td>First</td><td>Second</td></tr></table>';
+        }
+        return 'First\tSecond';
+      });
+
+      expect(new PasteMarkdownTable(data).isTable()).toBe(false);
+    });
   });
 
   describe('convertToTableMarkdown', () => {