1 files changed, 25 insertions, 0 deletions
diff --git a/scripts/frontend/stylelint/stylelint_duplicate_selectors.js b/scripts/frontend/stylelint/stylelint_duplicate_selectors.js
new file mode 100644
index 00000000000..77c1f1292b7
--- /dev/null
+++ b/scripts/frontend/stylelint/stylelint_duplicate_selectors.js
@@ -0,0 +1,25 @@
+const stylelint = require('stylelint');
+const utils = require('./stylelint_utils');
+
+const ruleName = 'stylelint-gitlab/duplicate-selectors';
+
+const messages = stylelint.utils.ruleMessages(ruleName, {
+  expected: (selector1, selector2) => {
+    return `"${selector1}" and "${selector2}" have the same properties.`;
+  },
+});
+
+module.exports = stylelint.createPlugin(ruleName, (enabled) => {
+  if (!enabled) {
+    return;
+  }
+
+  // eslint-disable-next-line consistent-return
+  return (root, result) => {
+    const selectorGroups = {};
+    utils.createPropertiesHashmap(root, result, ruleName, messages, selectorGroups, true);
+  };
+});
+
+module.exports.ruleName = ruleName;
+module.exports.messages = messages;