Update: fix no-magic-numbers false negative with ignoreArrayIndexes (#…

…12805)
eslint · Jan 28, 2020 · 562e784 · 562e784
1 parent f5b9656
commit 562e784
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Showing 2 changed files with 46 additions and 4 deletions.
diff --git a/lib/rules/no-magic-numbers.js b/lib/rules/no-magic-numbers.js
@@ -110,11 +110,14 @@ module.exports = {
 
         /**
          * Returns whether the number should be ignored when used as an array index with enabled 'ignoreArrayIndexes' option.
-         * @param {ASTNode} parent the non-"UnaryExpression" parent.
+         * @param {ASTNode} node Node to check
          * @returns {boolean} true if the number should be ignored
          */
-        function shouldIgnoreArrayIndexes(parent) {
-            return parent.type === "MemberExpression" && ignoreArrayIndexes;
+        function shouldIgnoreArrayIndexes(node) {
+            const parent = node.parent;
+
+            return ignoreArrayIndexes &&
+                parent.type === "MemberExpression" && parent.property === node;
         }
 
         return {
@@ -145,7 +148,7 @@ module.exports = {
 
                 if (shouldIgnoreNumber(value) ||
                     shouldIgnoreParseInt(parent, fullNumberNode) ||
-                    shouldIgnoreArrayIndexes(parent) ||
+                    shouldIgnoreArrayIndexes(fullNumberNode) ||
                     shouldIgnoreJSXNumbers(parent)) {
                     return;
                 }

diff --git a/tests/lib/rules/no-magic-numbers.js b/tests/lib/rules/no-magic-numbers.js
@@ -85,6 +85,27 @@ ruleTester.run("no-magic-numbers", rule, {
             code: "f(-100n)",
             options: [{ ignore: ["-100n"] }],
             parserOptions: { ecmaVersion: 2020 }
+        },
+
+        // Regression tests to preserve the behavior of ignoreArrayIndexes.
+        {
+            code: "var foo = bar[-100];",
+            options: [{
+                ignoreArrayIndexes: true
+            }]
+        },
+        {
+            code: "var foo = bar[1.5];",
+            options: [{
+                ignoreArrayIndexes: true
+            }]
+        },
+        {
+            code: "var foo = bar[100n];",
+            options: [{
+                ignoreArrayIndexes: true
+            }],
+            parserOptions: { ecmaVersion: 2020 }
         }
     ],
     invalid: [
@@ -236,6 +257,24 @@ ruleTester.run("no-magic-numbers", rule, {
                 messageId: "noMagic", data: { raw: "3" }, line: 1
             }]
         },
+        {
+            code: "100 .toString()",
+            options: [{
+                ignoreArrayIndexes: true
+            }],
+            errors: [{
+                messageId: "noMagic", data: { raw: "100" }, line: 1
+            }]
+        },
+        {
+            code: "200[100]",
+            options: [{
+                ignoreArrayIndexes: true
+            }],
+            errors: [{
+                messageId: "noMagic", data: { raw: "200" }, line: 1
+            }]
+        },
         {
             code: "var a = <div arrayProp={[1,2,3]}></div>;",
             parserOptions: {