Fix: no-undefined warned on non-computed property keys (fixes #7964)

eslint · Jan 28, 2017 · 2794cf6 · 2794cf6
1 parent 5ae6e00
commit 2794cf6
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Showing 2 changed files with 38 additions and 9 deletions.
diff --git a/lib/rules/no-undefined.js b/lib/rules/no-undefined.js
@@ -21,15 +21,38 @@ module.exports = {
 
     create(context) {
 
+        /**
+         * Returns true if an Identifier with name of "undefined" is in an
+         * acceptable location.
+         * @param {ASTNode} node The Identifer node to check.
+         * @returns {boolean} True if undefined is allowed here, false otherwise.
+         */
+        function isValidUndefinedIdentifier(node) {
+            switch (node.parent.type) {
+                case "MemberExpression":
+
+                    // foo.undefined is valid, foo[undefined] is not
+                    return node === node.parent.property && !node.parent.computed;
+
+                case "Property":
+
+                    // Only non-computed keys are valid here
+                    return node === node.parent.key &&
+                        !node.parent.computed;
+
+                default:
+                    return false;
+            }
+        }
+
         return {
 
             Identifier(node) {
-                if (node.name === "undefined") {
-                    const parent = context.getAncestors().pop();
-
-                    if (!parent || parent.type !== "MemberExpression" || node !== parent.property || parent.computed) {
-                        context.report({ node, message: "Unexpected use of undefined." });
-                    }
+                if (node.name === "undefined" && !isValidUndefinedIdentifier(node)) {
+                    context.report({
+                        node,
+                        message: "Unexpected use of undefined."
+                    });
                 }
             }
         };

diff --git a/tests/lib/rules/no-undefined.js b/tests/lib/rules/no-undefined.js
@@ -18,7 +18,7 @@ const rule = require("../../../lib/rules/no-undefined"),
 
 const errors = [{ message: "Unexpected use of undefined.", type: "Identifier" }];
 
-const ruleTester = new RuleTester();
+const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
 
 ruleTester.run("no-undefined", rule, {
     valid: [
@@ -31,7 +31,11 @@ ruleTester.run("no-undefined", rule, {
         "ndefined",
         "a.undefined",
         "this.undefined",
-        "global['undefined']"
+        "global['undefined']",
+
+        // https://github.com/eslint/eslint/issues/7964
+        "({ undefined: bar })",
+        "({ undefined: bar } = foo)"
     ],
     invalid: [
         { code: "undefined", errors },
@@ -44,6 +48,8 @@ ruleTester.run("no-undefined", rule, {
         { code: "try {} catch(undefined) {}", errors },
         { code: "(function undefined(){}())", errors },
         { code: "undefined = true", errors },
-        { code: "var undefined = true", errors }
+        { code: "var undefined = true", errors },
+        { code: "({ bar: undefined })", errors },
+        { code: "({ bar: undefined } = foo)", errors }
     ]
 });