Fix: arrow-body-style fixer for in wrap (fixes #11849)

lib/rules/arrow-body-style.js

@@ -99,6 +99,24 @@ module.exports = {
             return sourceCode.getTokenAfter(node);
         }
 
+        /**
+         * check if node has `in` operator or not
+         * @param {Node} node The argument node which needs to be checked
+         * @returns {boolean} `true` if there is an `in` operator else `false`.
+         */
+        function isIn(node) {
+            if (
+                node.type === "BinaryExpression" ||
+                node.type === "LogicalExpression"
+            ) {
+                if (node.operator === "in") {
+                    return true;
+                }
+                return isIn(node.left) || isIn(node.right);
+            }
+            return false;
+        }
+
         /**
          * Determines whether a arrow function body needs braces
          * @param {ASTNode} node The arrow function node.
@@ -157,6 +175,8 @@ module.exports = {
                                 sourceCode.commentsExistBetween(openingBrace, firstValueToken) ||
                                 sourceCode.commentsExistBetween(lastValueToken, closingBrace);
 
+                            const isInOp = isIn(blockBody[0].argument);
+
                             /*
                              * Remove tokens around the return value.
                              * If comments don't exist, remove extra spaces as well.
@@ -178,7 +198,7 @@ module.exports = {
                              * If the first token of the reutrn value is `{` or the return value is a sequence expression,
                              * enclose the return value by parentheses to avoid syntax error.
                              */
-                            if (astUtils.isOpeningBraceToken(firstValueToken) || blockBody[0].argument.type === "SequenceExpression") {
+                            if (astUtils.isOpeningBraceToken(firstValueToken) || blockBody[0].argument.type === "SequenceExpression" || isInOp) {
                                 fixes.push(
                                     fixer.insertTextBefore(firstValueToken, "("),
                                     fixer.insertTextAfter(lastValueToken, ")")

tests/lib/rules/arrow-body-style.js

@@ -45,6 +45,77 @@ ruleTester.run("arrow-body-style", rule, {
         { code: "var foo = () => { return { bar: 0 }; };", options: ["as-needed", { requireReturnForObjectLiteral: true }] }
     ],
     invalid: [
+        {
+            code: "for (let a = (b, c, d) => { return vb && c in d; }; ;);",
+            output: "for (let a = (b, c, d) => (vb && c in d); ;);",
+            errors: [
+                {
+                    line: 1,
+                    column: 27,
+                    messageId: "unexpectedSingleBlock"
+                }
+            ]
+        },
+        {
+            code: "for (let a = (b, c, d) => { return v in b && c in d; }; ;);",
+            output: "for (let a = (b, c, d) => (v in b && c in d); ;);",
+            errors: [
+                {
+                    line: 1,
+                    column: 27,
+                    messageId: "unexpectedSingleBlock"
+                }
+            ]
+        },
+        {
+            code: "for (let a = (b, c, d) => { return vb in dd ; }; ;);",
+            output: "for (let a = (b, c, d) => (vb in dd ); ;);",
+            errors: [
+                {
+                    line: 1,
+                    column: 27,
+                    messageId: "unexpectedSingleBlock"
+                }
+            ]
+        },
+        {
+            code: "for (let a = (b, c, d) => { return vb in c in dd ; }; ;);",
+            output: "for (let a = (b, c, d) => (vb in c in dd ); ;);",
+            errors: [
+                {
+                    line: 1,
+                    column: 27,
+                    messageId: "unexpectedSingleBlock"
+                }
+            ]
+        },
+        {
+            code: "do{let a = () => {return f in ff}}while(true){}",
+            output: "do{let a = () => (f in ff)}while(true){}",
+            errors: [{
+                line: 1,
+                column: 18,
+                messageId: "unexpectedSingleBlock"
+            }]
+        },
+        {
+            code: "scores.map(score => { return x in +(score / maxScore).toFixed(2)});",
+            output: "scores.map(score => (x in +(score / maxScore).toFixed(2)));",
+            errors: [{
+                line: 1,
+                column: 21,
+                messageId: "unexpectedSingleBlock"
+            }]
+        },
+        {
+            code: "const fn = (a, b) => { return a + x in Number(b) };",
+            output: "const fn = (a, b) => (a + x in Number(b));",
+            errors: [{
+                line: 1,
+                column: 22,
+                messageId: "unexpectedSingleBlock"
+            }]
+        },
         {
             code: "var foo = () => 0",
             output: "var foo = () => {return 0}",