1 files changed, 76 insertions, 0 deletions
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-useless-run-test.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-useless-run-test.js
new file mode 100644
index 0000000000..ddfbea05e3
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-useless-run-test.js
@@ -0,0 +1,76 @@
+/**
+ * @fileoverview Reject run_test() definitions where they aren't necessary.
+ *
+ * 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";
+
+module.exports = {
+  meta: {
+    docs: {
+      url: "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/rules/no-useless-run-test.html",
+    },
+    fixable: "code",
+    messages: {
+      noUselessRunTest:
+        "Useless run_test function - only contains run_next_test; whole function can be removed",
+    },
+    schema: [],
+    type: "suggestion",
+  },
+
+  create(context) {
+    return {
+      "Program > FunctionDeclaration": function (node) {
+        if (
+          node.id.name === "run_test" &&
+          node.body.type === "BlockStatement" &&
+          node.body.body.length === 1 &&
+          node.body.body[0].type === "ExpressionStatement" &&
+          node.body.body[0].expression.type === "CallExpression" &&
+          node.body.body[0].expression.callee.name === "run_next_test"
+        ) {
+          context.report({
+            node,
+            fix: fixer => {
+              let sourceCode = context.getSourceCode();
+              let startNode;
+              if (sourceCode.getCommentsBefore) {
+                // ESLint 4 has getCommentsBefore.
+                startNode = sourceCode.getCommentsBefore(node);
+              } else if (node && node.body && node.leadingComments) {
+                // This is for ESLint 3.
+                startNode = node.leadingComments;
+              }
+
+              // If we have comments, we want the start node to be the comments,
+              // rather than the token before the comments, so that we don't
+              // remove the comments - for run_test, these are likely to be useful
+              // information about the test.
+              if (startNode?.length) {
+                startNode = startNode[startNode.length - 1];
+              } else {
+                startNode = sourceCode.getTokenBefore(node);
+              }
+
+              return fixer.removeRange([
+                // If there's no startNode, we fall back to zero, i.e. start of
+                // file.
+                startNode ? startNode.range[1] + 1 : 0,
+                // We know the function is a block and it'll end with }. Normally
+                // there's a new line after that, so just advance past it. This
+                // may be slightly not dodgy in some cases, but covers the existing
+                // cases.
+                node.range[1] + 1,
+              ]);
+            },
+            messageId: "noUselessRunTest",
+          });
+        }
+      },
+    };
+  },
+};