no-loop-func.js

/**
 * @fileoverview Tests for no-loop-func rule.
 * @author Ilya Volodin
 */

"use strict";

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

const rule = require("../../../lib/rules/no-loop-func"),
    RuleTester = require("../../../lib/rule-tester/rule-tester");

//------------------------------------------------------------------------------
// Tests
//------------------------------------------------------------------------------

const ruleTester = new RuleTester();

ruleTester.run("no-loop-func", rule, {
    valid: [
        "string = 'function a() {}';",
        "for (var i=0; i<l; i++) { } var a = function() { i; };",
        "for (var i=0, a=function() { i; }; i<l; i++) { }",
        "for (var x in xs.filter(function(x) { return x != upper; })) { }",
        {
            code: "for (var x of xs.filter(function(x) { return x != upper; })) { }",
            languageOptions: { ecmaVersion: 6 }
        },

        // no refers to variables that declared on upper scope.
        "for (var i=0; i<l; i++) { (function() {}) }",
        "for (var i in {}) { (function() {}) }",
        {
            code: "for (var i of {}) { (function() {}) }",
            languageOptions: { ecmaVersion: 6 }
        },

        // functions which are using unmodified variables are OK.
        {
            code: "for (let i=0; i<l; i++) { (function() { i; }) }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (let i in {}) { i = 7; (function() { i; }) }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (const i of {}) { (function() { i; }) }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (let i = 0; i < 10; ++i) { for (let x in xs.filter(x => x != i)) {  } }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a = 0; for (let i=0; i<l; i++) { (function() { a; }); }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a = 0; for (let i in {}) { (function() { a; }); }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a = 0; for (let i of {}) { (function() { a; }); }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a = 0; for (let i=0; i<l; i++) { (function() { (function() { a; }); }); }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a = 0; for (let i in {}) { function foo() { (function() { a; }); } }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a = 0; for (let i of {}) { (() => { (function() { a; }); }); }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "var a = 0; for (let i=0; i<l; i++) { (function() { a; }); }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "var a = 0; for (let i in {}) { (function() { a; }); }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "var a = 0; for (let i of {}) { (function() { a; }); }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: [
                "let result = {};",
                "for (const score in scores) {",
                "  const letters = scores[score];",
                "  letters.split('').forEach(letter => {",
                "    result[letter] = score;",
                "  });",
                "}",
                "result.__default = 6;"
            ].join("\n"),
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: [
                "while (true) {",
                "    (function() { a; });",
                "}",
                "let a;"
            ].join("\n"),
            languageOptions: { ecmaVersion: 6 }
        },

        /*
         * These loops _look_ like they might be unsafe, but because i is undeclared, they're fine
         * at least as far as this rule is concerned - the loop doesn't declare/generate the variable.
         */
        "while(i) { (function() { i; }) }",
        "do { (function() { i; }) } while (i)",

        /**
         * These loops _look_ like they might be unsafe, but because i is declared outside the loop
         * and is not updated in or after the loop, they're fine as far as this rule is concerned.
         * The variable that's captured is just the one variable shared by all the loops, but that's
         * explicitly expected in these cases.
         */
        "var i; while(i) { (function() { i; }) }",
        "var i; do { (function() { i; }) } while (i)",

        /**
         * These loops use an undeclared variable, and so shouldn't be flagged by this rule,
         * they'll be picked up by no-undef.
         */
        {
            code: "for (var i=0; i<l; i++) { (function() { undeclared; }) }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (let i=0; i<l; i++) { (function() { undeclared; }) }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (var i in {}) { i = 7; (function() { undeclared; }) }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (let i in {}) { i = 7; (function() { undeclared; }) }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (const i of {}) { (function() { undeclared; }) }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (let i = 0; i < 10; ++i) { for (let x in xs.filter(x => x != undeclared)) {  } }",
            languageOptions: { ecmaVersion: 6 },
        },

        // IIFE
        {
            code: `
            let current = getStart();
            while (current) {
            (() => {
                current;
                current.a;
                current.b;
                current.c;
                current.d;
            })();
            
            current = current.upper;
            }
            `,
            languageOptions: { ecmaVersion: 6 }
        },
        "for (var i=0; (function() { i; })(), i<l; i++) { }",
        "for (var i=0; i<l; (function() { i; })(), i++) { }",
        {
            code: "for (let i = 0; i < 10; ++i) { (()=>{ i;})() }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (let i = 0; i < 10; ++i) { (function a(){i;})() }",
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i++) {
                arr.push((f => f)((() => i)()));
            }
            `,
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i++) {
                arr.push((() => {
                    return (() => i)();
                })());
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        }

    ],
    invalid: [
        {
            code: "for (var i=0; i<l; i++) { (function() { i; }) }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "FunctionExpression" }]
        },
        {
            code: "for (var i=0; i<l; i++) { for (var j=0; j<m; j++) { (function() { i+j; }) } }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i', 'j'" }, type: "FunctionExpression" }]
        },
        {
            code: "for (var i in {}) { (function() { i; }) }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "FunctionExpression" }]
        },
        {
            code: "for (var i of {}) { (function() { i; }) }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (var i=0; i < l; i++) { (() => { i; }) }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (var i=0; i < l; i++) { var a = function() { i; } }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "FunctionExpression" }]
        },
        {
            code: "for (var i=0; i < l; i++) { function a() { i; }; a(); }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "FunctionDeclaration" }]
        },

        // Warns functions which are using modified variables.
        {
            code: "let a; for (let i=0; i<l; i++) { a = 1; (function() { a; });}",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a; for (let i in {}) { (function() { a; }); a = 1; }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a; for (let i of {}) { (function() { a; }); } a = 1; ",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a; for (let i=0; i<l; i++) { (function() { (function() { a; }); }); a = 1; }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a; for (let i in {}) { a = 1; function foo() { (function() { a; }); } }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionDeclaration" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a; for (let i of {}) { (() => { (function() { a; }); }); } a = 1;",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (var i = 0; i < 10; ++i) { for (let x in xs.filter(x => x != i)) {  } }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (let x of xs) { let a; for (let y of ys) { a = 1; (function() { a; }); } }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (var x of xs) { for (let y of ys) { (function() { x; }); } }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'x'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "for (var x of xs) { (function() { x; }); }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'x'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "var a; for (let x of xs) { a = 1; (function() { a; }); }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "var a; for (let x of xs) { (function() { a; }); a = 1; }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a; function foo() { a = 10; } for (let x of xs) { (function() { a; }); } foo();",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a; function foo() { a = 10; for (let x of xs) { (function() { a; }); } } foo();",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'a'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },

        // IIFE
        {
            code: "let a; for (var i=0; i<l; i++) { (function* (){i;})() }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: "let a; for (var i=0; i<l; i++) { (async function (){i;})() }",
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 2022 }
        },
        {
            code: `
            let current = getStart();
            const arr = [];
            while (current) {
                (function f() {
                    current;
                    arr.push(f);
                })();
                
                current = current.upper;
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'current'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i++) {
                (function fun () {
                    if (arr.includes(fun)) return i;
                    else arr.push(fun);
                })();
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: `
            let current = getStart();
            const arr = [];
            while (current) {
                const p = (async () => {
                    await someDelay();
                    current;
                })();

                arr.push(p);
                current = current.upper;
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'current'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 2022 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i++) {
                arr.push((f => f)(() => i));
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i++) {
                arr.push((() => {
                    return () => i;
                })());
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i++) {
                arr.push((() => {
                    return () => { return i };
                })());
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i++) {
                arr.push((() => {
                    return () => { return () => i };
                })());
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i++) {
                arr.push((() => {
                    return () => (() => i)();
                })());
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 6 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i ++) {
                (() => {
                    arr.push((async () => {
                        await 1;
                        return i;
                    })());
                })();
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "ArrowFunctionExpression" }],
            languageOptions: { ecmaVersion: 2022 }
        },
        {
            code: `
            var arr = [];

            for (var i = 0; i < 5; i ++) {
                (() => {
                    (function f() {
                        if (!arr.includes(f)) {
                            arr.push(f);
                        }
                        return i;
                    })();
                })();
            
            }
            `,
            errors: [{ messageId: "unsafeRefs", data: { varNames: "'i'" }, type: "FunctionExpression" }],
            languageOptions: { ecmaVersion: 2022 }
        }
    ]
});