1 files changed, 45 insertions, 0 deletions
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/reject-top-level-await.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/reject-top-level-await.js
new file mode 100644
index 0000000000..dff7db0f9a
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/reject-top-level-await.js
@@ -0,0 +1,45 @@
+/**
+ * @fileoverview Don't allow only() in tests
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+"use strict";
+
+var helpers = require("../helpers");
+
+module.exports = {
+  meta: {
+    docs: {
+      url: "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/rules/reject-top-level-await.html",
+    },
+    messages: {
+      rejectTopLevelAwait:
+        "Top-level await is not currently supported in component files.",
+    },
+    schema: [],
+    type: "problem",
+  },
+
+  create(context) {
+    return {
+      AwaitExpression(node) {
+        if (!helpers.getIsTopLevelScript(context.getAncestors())) {
+          return;
+        }
+        context.report({ node, messageId: "rejectTopLevelAwait" });
+      },
+      ForOfStatement(node) {
+        if (
+          !node.await ||
+          !helpers.getIsTopLevelScript(context.getAncestors())
+        ) {
+          return;
+        }
+        context.report({ node, messageId: "rejectTopLevelAwait" });
+      },
+    };
+  },
+};