rule-tester.js

/**
 * @fileoverview Tests for ESLint Tester
 * @author Nicholas C. Zakas
 */
"use strict";

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const sinon = require("sinon"),
    EventEmitter = require("events"),
    { RuleTester } = require("../../../lib/rule-tester"),
    assert = require("chai").assert,
    nodeAssert = require("assert"),
    espree = require("espree");

const NODE_ASSERT_STRICT_EQUAL_OPERATOR = (() => {
    try {
        nodeAssert.strictEqual(1, 2);
    } catch (err) {
        return err.operator;
    }
    throw new Error("unexpected successful assertion");
})();

/**
 * Do nothing.
 * @returns {void}
 */
function noop() {

    // do nothing.
}

//------------------------------------------------------------------------------
// Rewire Things
//------------------------------------------------------------------------------

/*
 * So here's the situation. Because RuleTester uses it() and describe() from
 * Mocha, any failures would show up in the output of this test file. That means
 * when we tested that a failure is thrown, that would also count as a failure
 * in the testing for RuleTester. In order to remove those results from the
 * results of this file, we need to overwrite it() and describe() just in
 * RuleTester to do nothing but run code. Effectively, it() and describe()
 * just become regular functions inside of index.js, not at all related to Mocha.
 * That allows the results of this file to be untainted and therefore accurate.
 *
 * To assert that the right arguments are passed to RuleTester.describe/it, an
 * event emitter is used which emits the arguments.
 */

const ruleTesterTestEmitter = new EventEmitter();

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

describe("RuleTester", () => {

    // Stub `describe()` and `it()` while this test suite.
    before(() => {
        RuleTester.describe = function(text, method) {
            ruleTesterTestEmitter.emit("describe", text, method);
            return method.call(this);
        };
        RuleTester.it = function(text, method) {
            ruleTesterTestEmitter.emit("it", text, method);
            return method.call(this);
        };
    });
    after(() => {
        RuleTester.describe = null;
        RuleTester.it = null;
    });

    let ruleTester;

    /**
     * A helper function to verify Node.js core error messages.
     * @param {string} actual The actual input
     * @param {string} expected The expected input
     * @returns {Function} Error callback to verify that the message is correct
     *                     for the actual and expected input.
     */
    function assertErrorMatches(actual, expected) {
        const err = new nodeAssert.AssertionError({
            actual,
            expected,
            operator: NODE_ASSERT_STRICT_EQUAL_OPERATOR
        });

        return err.message;
    }

    beforeEach(() => {
        RuleTester.resetDefaultConfig();
        ruleTester = new RuleTester();
    });

    it("should not throw an error when everything passes", () => {
        ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
            valid: [
                "Eval(foo)"
            ],
            invalid: [
                { code: "eval(foo)", errors: [{ message: "eval sucks.", type: "CallExpression" }] }
            ]
        });
    });

    it("should throw an error when valid code is invalid", () => {

        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "eval(foo)"
                ],
                invalid: [
                    { code: "eval(foo)", errors: [{ message: "eval sucks.", type: "CallExpression" }] }
                ]
            });
        }, /Should have no errors but had 1/u);
    });

    it("should throw an error when valid code is invalid", () => {

        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    { code: "eval(foo)" }
                ],
                invalid: [
                    { code: "eval(foo)", errors: [{ message: "eval sucks.", type: "CallExpression" }] }
                ]
            });
        }, /Should have no errors but had 1/u);
    });

    it("should throw an error if invalid code is valid", () => {

        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "Eval(foo)"
                ],
                invalid: [
                    { code: "Eval(foo)", errors: [{ message: "eval sucks.", type: "CallExpression" }] }
                ]
            });
        }, /Should have 1 error but had 0/u);
    });

    it("should throw an error when the error message is wrong", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {

                // Only the invalid test matters here
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", errors: [{ message: "Bad error message." }] }
                ]
            });
        }, assertErrorMatches("Bad var.", "Bad error message."));
    });

    it("should throw an error when the error message regex does not match", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [],
                invalid: [
                    { code: "var foo = bar;", errors: [{ message: /Bad error message/u }] }
                ]
            });
        }, /Expected 'Bad var.' to match \/Bad error message\//u);
    });

    it("should throw an error when the error is not a supported type", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {

                // Only the invalid test matters here
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", errors: [42] }
                ]
            });
        }, /Error should be a string, object, or RegExp/u);
    });

    it("should throw an error when any of the errors is not a supported type", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {

                // Only the invalid test matters here
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar; var baz = quux", errors: [{ type: "VariableDeclaration" }, null] }
                ]
            });
        }, /Error should be a string, object, or RegExp/u);
    });

    it("should throw an error when the error is a string and it does not match error message", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {

                // Only the invalid test matters here
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", errors: ["Bad error message."] }
                ]
            });
        }, assertErrorMatches("Bad var.", "Bad error message."));
    });

    it("should throw an error when the error is a string and it does not match error message", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {

                valid: [
                ],
                invalid: [
                    { code: "var foo = bar;", errors: [/Bad error message/u] }
                ]
            });
        }, /Expected 'Bad var.' to match \/Bad error message\//u);
    });

    it("should not throw an error when the error is a string and it matches error message", () => {
        ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {

            // Only the invalid test matters here
            valid: [
                "bar = baz;"
            ],
            invalid: [
                { code: "var foo = bar;", output: " foo = bar;", errors: ["Bad var."] }
            ]
        });
    });

    it("should not throw an error when the error is a regex and it matches error message", () => {
        ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
            valid: [],
            invalid: [
                { code: "var foo = bar;", output: " foo = bar;", errors: [/^Bad var/u] }
            ]
        });
    });

    it("should throw an error when the error is an object with an unknown property name", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", errors: [{ Message: "Bad var." }] }
                ]
            });
        }, /Invalid error property name 'Message'/u);
    });

    it("should throw an error when any of the errors is an object with an unknown property name", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    {
                        code: "var foo = bar; var baz = quux",
                        errors: [
                            { message: "Bad var.", type: "VariableDeclaration" },
                            { message: "Bad var.", typo: "VariableDeclaration" }
                        ]
                    }
                ]
            });
        }, /Invalid error property name 'typo'/u);
    });

    it("should not throw an error when the error is a regex in an object and it matches error message", () => {
        ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
            valid: [],
            invalid: [
                { code: "var foo = bar;", output: " foo = bar;", errors: [{ message: /^Bad var/u }] }
            ]
        });
    });

    it("should throw an error when the expected output doesn't match", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", output: "foo = bar", errors: [{ message: "Bad var.", type: "VariableDeclaration" }] }
                ]
            });
        }, /Output is incorrect/u);
    });

    it("should use strict equality to compare output", () => {
        const replaceProgramWith5Rule = {
            meta: {
                fixable: "code"
            },

            create: context => ({
                Program(node) {
                    context.report({ node, message: "bad", fix: fixer => fixer.replaceText(node, "5") });
                }
            })
        };

        // Should not throw.
        ruleTester.run("foo", replaceProgramWith5Rule, {
            valid: [],
            invalid: [
                { code: "var foo = bar;", output: "5", errors: 1 }
            ]
        });

        assert.throws(() => {
            ruleTester.run("foo", replaceProgramWith5Rule, {
                valid: [],
                invalid: [
                    { code: "var foo = bar;", output: 5, errors: 1 }
                ]
            });
        }, /Output is incorrect/u);
    });

    it("should throw an error when the expected output doesn't match and errors is just a number", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", output: "foo = bar", errors: 1 }
                ]
            });
        }, /Output is incorrect/u);
    });

    it("should not throw an error when the expected output is null and no errors produce output", () => {
        ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
            valid: [
                "bar = baz;"
            ],
            invalid: [
                { code: "eval(x)", errors: 1, output: null },
                { code: "eval(x); eval(y);", errors: 2, output: null }
            ]
        });
    });

    it("should throw an error when the expected output is null and problems produce output", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", output: null, errors: 1 }
                ]
            });
        }, /Expected no autofixes to be suggested/u);

        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    {
                        code: "var foo = bar; var qux = boop;",
                        output: null,
                        errors: 2
                    }
                ]
            });
        }, /Expected no autofixes to be suggested/u);
    });

    it("should throw an error when the expected output is null and only some problems produce output", () => {
        assert.throws(() => {
            ruleTester.run("fixes-one-problem", require("../../fixtures/testers/rule-tester/fixes-one-problem"), {
                valid: [],
                invalid: [
                    { code: "foo", output: null, errors: 2 }
                ]
            });
        }, /Expected no autofixes to be suggested/u);
    });

    it("should throw an error when the expected output isn't specified and problems produce output", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", errors: 1 }
                ]
            });
        }, "The rule fixed the code. Please add 'output' property.");
    });

    it("should throw an error if invalid code specifies wrong type", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "Eval(foo)"
                ],
                invalid: [
                    { code: "eval(foo)", errors: [{ message: "eval sucks.", type: "CallExpression2" }] }
                ]
            });
        }, /Error type should be CallExpression2, found CallExpression/u);
    });

    it("should throw an error if invalid code specifies wrong line", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "Eval(foo)"
                ],
                invalid: [
                    { code: "eval(foo)", errors: [{ message: "eval sucks.", type: "CallExpression", line: 5 }] }
                ]
            });
        }, /Error line should be 5/u);
    });

    it("should not skip line assertion if line is a falsy value", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "Eval(foo)"
                ],
                invalid: [
                    { code: "\neval(foo)", errors: [{ message: "eval sucks.", type: "CallExpression", line: 0 }] }
                ]
            });
        }, /Error line should be 0/u);
    });

    it("should throw an error if invalid code specifies wrong column", () => {
        const wrongColumn = 10,
            expectedErrorMessage = "Error column should be 1";

        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: ["Eval(foo)"],
                invalid: [{
                    code: "eval(foo)",
                    errors: [{
                        message: "eval sucks.",
                        column: wrongColumn
                    }]
                }]
            });
        }, expectedErrorMessage);
    });

    it("should throw error for empty error array", () => {
        assert.throws(() => {
            ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                valid: [],
                invalid: [{
                    code: "var foo;",
                    errors: []
                }]
            });
        }, /Invalid cases must have at least one error/u);
    });

    it("should throw error for errors : 0", () => {
        assert.throws(() => {
            ruleTester.run(
                "suggestions-messageIds",
                require("../../fixtures/testers/rule-tester/suggestions")
                    .withMessageIds,
                {
                    valid: [],
                    invalid: [
                        {
                            code: "var foo;",
                            errors: 0
                        }
                    ]
                }
            );
        }, /Invalid cases must have 'error' value greater than 0/u);
    });

    it("should not skip column assertion if column is a falsy value", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: ["Eval(foo)"],
                invalid: [{
                    code: "var foo; eval(foo)",
                    errors: [{ message: "eval sucks.", column: 0 }]
                }]
            });
        }, /Error column should be 0/u);
    });

    it("should throw an error if invalid code specifies wrong endLine", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", output: "foo = bar", errors: [{ message: "Bad var.", type: "VariableDeclaration", endLine: 10 }] }
                ]
            });
        }, "Error endLine should be 10");
    });

    it("should throw an error if invalid code specifies wrong endColumn", () => {
        assert.throws(() => {
            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "bar = baz;"
                ],
                invalid: [
                    { code: "var foo = bar;", output: "foo = bar", errors: [{ message: "Bad var.", type: "VariableDeclaration", endColumn: 10 }] }
                ]
            });
        }, "Error endColumn should be 10");
    });

    it("should throw an error if invalid code has the wrong number of errors", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "Eval(foo)"
                ],
                invalid: [
                    {
                        code: "eval(foo)",
                        errors: [
                            { message: "eval sucks.", type: "CallExpression" },
                            { message: "eval sucks.", type: "CallExpression" }
                        ]
                    }
                ]
            });
        }, /Should have 2 errors but had 1/u);
    });

    it("should throw an error if invalid code does not have errors", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "Eval(foo)"
                ],
                invalid: [
                    { code: "eval(foo)" }
                ]
            });
        }, /Did not specify errors for an invalid test of no-eval/u);
    });

    it("should throw an error if invalid code has the wrong explicit number of errors", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "Eval(foo)"
                ],
                invalid: [
                    { code: "eval(foo)", errors: 2 }
                ]
            });
        }, /Should have 2 errors but had 1/u);
    });

    it("should throw an error if there's a parsing error in a valid test", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "1eval('foo')"
                ],
                invalid: [
                    { code: "eval('foo')", errors: [{}] }
                ]
            });
        }, /fatal parsing error/iu);
    });

    it("should throw an error if there's a parsing error in an invalid test", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "noeval('foo')"
                ],
                invalid: [
                    { code: "1eval('foo')", errors: [{}] }
                ]
            });
        }, /fatal parsing error/iu);
    });

    it("should throw an error if there's a parsing error in an invalid test and errors is just a number", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    "noeval('foo')"
                ],
                invalid: [
                    { code: "1eval('foo')", errors: 1 }
                ]
            });
        }, /fatal parsing error/iu);
    });

    // https://github.com/eslint/eslint/issues/4779
    it("should throw an error if there's a parsing error and output doesn't match", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [],
                invalid: [
                    { code: "eval(`foo`)", output: "eval(`foo`);", errors: [{}] }
                ]
            });
        }, /fatal parsing error/iu);
    });

    it("should not throw an error if invalid code has at least an expected empty error object", () => {
        ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
            valid: ["Eval(foo)"],
            invalid: [{
                code: "eval(foo)",
                errors: [{}]
            }]
        });
    });

    it("should pass-through the globals config of valid tests to the to rule", () => {
        ruleTester.run("no-test-global", require("../../fixtures/testers/rule-tester/no-test-global"), {
            valid: [
                "var test = 'foo'",
                {
                    code: "var test2 = 'bar'",
                    globals: { test: true }
                }
            ],
            invalid: [{ code: "bar", errors: 1 }]
        });
    });

    it("should pass-through the globals config of invalid tests to the to rule", () => {
        ruleTester.run("no-test-global", require("../../fixtures/testers/rule-tester/no-test-global"), {
            valid: ["var test = 'foo'"],
            invalid: [
                {
                    code: "var test = 'foo'; var foo = 'bar'",
                    errors: 1
                },
                {
                    code: "var test = 'foo'",
                    globals: { foo: true },
                    errors: [{ message: "Global variable foo should not be used." }]
                }
            ]
        });
    });

    it("should pass-through the settings config to rules", () => {
        ruleTester.run("no-test-settings", require("../../fixtures/testers/rule-tester/no-test-settings"), {
            valid: [
                {
                    code: "var test = 'bar'", settings: { test: 1 }
                }
            ],
            invalid: [
                {
                    code: "var test = 'bar'", settings: { "no-test": 22 }, errors: 1
                }
            ]
        });
    });

    it("should pass-through the filename to the rule", () => {
        (function() {
            ruleTester.run("", require("../../fixtures/testers/rule-tester/no-test-filename"), {
                valid: [
                    {
                        code: "var foo = 'bar'",
                        filename: "somefile.js"
                    }
                ],
                invalid: [
                    {
                        code: "var foo = 'bar'",
                        errors: [
                            { message: "Filename test was not defined." }
                        ]
                    }
                ]
            });
        }());
    });

    it("should pass-through the options to the rule", () => {
        ruleTester.run("no-invalid-args", require("../../fixtures/testers/rule-tester/no-invalid-args"), {
            valid: [
                {
                    code: "var foo = 'bar'",
                    options: [false]
                }
            ],
            invalid: [
                {
                    code: "var foo = 'bar'",
                    options: [true],
                    errors: [{ message: "Invalid args" }]
                }
            ]
        });
    });

    it("should throw an error if the options are an object", () => {
        assert.throws(() => {
            ruleTester.run("no-invalid-args", require("../../fixtures/testers/rule-tester/no-invalid-args"), {
                valid: [
                    {
                        code: "foo",
                        options: { ok: true }
                    }
                ],
                invalid: []
            });
        }, /options must be an array/u);
    });

    it("should throw an error if the options are a number", () => {
        assert.throws(() => {
            ruleTester.run("no-invalid-args", require("../../fixtures/testers/rule-tester/no-invalid-args"), {
                valid: [
                    {
                        code: "foo",
                        options: 0
                    }
                ],
                invalid: []
            });
        }, /options must be an array/u);
    });

    it("should pass-through the parser to the rule", () => {
        const spy = sinon.spy(ruleTester.linter, "verify");

        ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
            valid: [
                {
                    code: "Eval(foo)"
                }
            ],
            invalid: [
                {
                    code: "eval(foo)",
                    parser: require.resolve("esprima"),
                    errors: [{ line: 1 }]
                }
            ]
        });
        assert.strictEqual(spy.args[1][1].parser, require.resolve("esprima"));
    });
    it("should pass normalized ecmaVersion to the rule", () => {
        const reportEcmaVersionRule = {
            meta: {
                messages: {
                    ecmaVersionMessage: "context.parserOptions.ecmaVersion is {{type}} {{ecmaVersion}}."
                }
            },
            create: context => ({
                Program(node) {
                    const { ecmaVersion } = context.parserOptions;

                    context.report({
                        node,
                        messageId: "ecmaVersionMessage",
                        data: { type: typeof ecmaVersion, ecmaVersion }
                    });
                }
            })
        };

        const notEspree = require.resolve("../../fixtures/parsers/empty-program-parser");

        ruleTester.run("report-ecma-version", reportEcmaVersionRule, {
            valid: [],
            invalid: [
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "undefined", ecmaVersion: "undefined" } }]
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "undefined", ecmaVersion: "undefined" } }],
                    parserOptions: {}
                },
                {
                    code: "<div/>",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "undefined", ecmaVersion: "undefined" } }],
                    parserOptions: { ecmaFeatures: { jsx: true } }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "undefined", ecmaVersion: "undefined" } }],
                    parser: require.resolve("espree")
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "6" } }],
                    parserOptions: { ecmaVersion: 6 }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "6" } }],
                    parserOptions: { ecmaVersion: 2015 }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "undefined", ecmaVersion: "undefined" } }],
                    env: { browser: true }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "undefined", ecmaVersion: "undefined" } }],
                    env: { es6: false }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "6" } }],
                    env: { es6: true }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "8" } }],
                    env: { es6: false, es2017: true }
                },
                {
                    code: "let x",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "6" } }],
                    env: { es6: "truthy" }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "8" } }],
                    env: { es2017: true }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "11" } }],
                    env: { es2020: true }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "12" } }],
                    env: { es2021: true }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: String(espree.latestEcmaVersion) } }],
                    parserOptions: { ecmaVersion: "latest" }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: String(espree.latestEcmaVersion) } }],
                    parser: require.resolve("espree"),
                    parserOptions: { ecmaVersion: "latest" }
                },
                {
                    code: "<div/>",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: String(espree.latestEcmaVersion) } }],
                    parserOptions: { ecmaVersion: "latest", ecmaFeatures: { jsx: true } }
                },
                {
                    code: "import 'foo'",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: String(espree.latestEcmaVersion) } }],
                    parserOptions: { ecmaVersion: "latest", sourceType: "module" }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: String(espree.latestEcmaVersion) } }],
                    parserOptions: { ecmaVersion: "latest" },
                    env: { es6: true }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: String(espree.latestEcmaVersion) } }],
                    parserOptions: { ecmaVersion: "latest" },
                    env: { es2020: true }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "undefined", ecmaVersion: "undefined" } }],
                    parser: notEspree
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "undefined", ecmaVersion: "undefined" } }],
                    parser: notEspree,
                    parserOptions: {}
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "5" } }],
                    parser: notEspree,
                    parserOptions: { ecmaVersion: 5 }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "6" } }],
                    parser: notEspree,
                    parserOptions: { ecmaVersion: 6 }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "6" } }],
                    parser: notEspree,
                    parserOptions: { ecmaVersion: 2015 }
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "string", ecmaVersion: "latest" } }],
                    parser: notEspree,
                    parserOptions: { ecmaVersion: "latest" }
                }
            ]
        });

        [{ parserOptions: { ecmaVersion: 6 } }, { env: { es6: true } }].forEach(options => {
            new RuleTester(options).run("report-ecma-version", reportEcmaVersionRule, {
                valid: [],
                invalid: [
                    {
                        code: "",
                        errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "6" } }]
                    },
                    {
                        code: "",
                        errors: [{ messageId: "ecmaVersionMessage", data: { type: "number", ecmaVersion: "6" } }],
                        parserOptions: {}
                    }
                ]
            });
        });

        new RuleTester({ parser: notEspree }).run("report-ecma-version", reportEcmaVersionRule, {
            valid: [],
            invalid: [
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "undefined", ecmaVersion: "undefined" } }]
                },
                {
                    code: "",
                    errors: [{ messageId: "ecmaVersionMessage", data: { type: "string", ecmaVersion: "latest" } }],
                    parserOptions: { ecmaVersion: "latest" }
                }
            ]
        });
    });

    it("should pass-through services from parseForESLint to the rule", () => {
        const enhancedParserPath = require.resolve("../../fixtures/parsers/enhanced-parser");
        const disallowHiRule = {
            create: context => ({
                Literal(node) {
                    const disallowed = context.parserServices.test.getMessage(); // returns "Hi!"

                    if (node.value === disallowed) {
                        context.report({ node, message: `Don't use '${disallowed}'` });
                    }
                }
            })
        };

        ruleTester.run("no-hi", disallowHiRule, {
            valid: [
                {
                    code: "'Hello!'",
                    parser: enhancedParserPath
                }
            ],
            invalid: [
                {
                    code: "'Hi!'",
                    parser: enhancedParserPath,
                    errors: [{ message: "Don't use 'Hi!'" }]
                }
            ]
        });
    });

    it("should prevent invalid options schemas", () => {
        assert.throws(() => {
            ruleTester.run("no-invalid-schema", require("../../fixtures/testers/rule-tester/no-invalid-schema"), {
                valid: [
                    "var answer = 6 * 7;",
                    { code: "var answer = 6 * 7;", options: [] }
                ],
                invalid: [
                    { code: "var answer = 6 * 7;", options: ["bar"], errors: [{ message: "Expected nothing." }] }
                ]
            });
        }, "Schema for rule no-invalid-schema is invalid:,\titems: should be object\n\titems[0].enum: should NOT have fewer than 1 items\n\titems: should match some schema in anyOf");

    });

    it("should prevent schema violations in options", () => {
        assert.throws(() => {
            ruleTester.run("no-schema-violation", require("../../fixtures/testers/rule-tester/no-schema-violation"), {
                valid: [
                    "var answer = 6 * 7;",
                    { code: "var answer = 6 * 7;", options: ["foo"] }
                ],
                invalid: [
                    { code: "var answer = 6 * 7;", options: ["bar"], errors: [{ message: "Expected foo." }] }
                ]
            });
        }, /Value "bar" should be equal to one of the allowed values./u);

    });

    it("should disallow invalid defaults in rules", () => {
        const ruleWithInvalidDefaults = {
            meta: {
                schema: [
                    {
                        oneOf: [
                            { enum: ["foo"] },
                            {
                                type: "object",
                                properties: {
                                    foo: {
                                        enum: ["foo", "bar"],
                                        default: "foo"
                                    }
                                },
                                additionalProperties: false
                            }
                        ]
                    }
                ]
            },
            create: () => ({})
        };

        assert.throws(() => {
            ruleTester.run("invalid-defaults", ruleWithInvalidDefaults, {
                valid: [
                    {
                        code: "foo",
                        options: [{}]
                    }
                ],
                invalid: []
            });
        }, /Schema for rule invalid-defaults is invalid: default is ignored for: data1\.foo/u);
    });

    it("throw an error when an unknown config option is included", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    { code: "Eval(foo)", foo: "bar" }
                ],
                invalid: []
            });
        }, /ESLint configuration in rule-tester is invalid./u);
    });

    it("throw an error when an invalid config value is included", () => {
        assert.throws(() => {
            ruleTester.run("no-eval", require("../../fixtures/testers/rule-tester/no-eval"), {
                valid: [
                    { code: "Eval(foo)", env: ["es6"] }
                ],
                invalid: []
            });
        }, /Property "env" is the wrong type./u);
    });

    it("should pass-through the tester config to the rule", () => {
        ruleTester = new RuleTester({
            globals: { test: true }
        });

        ruleTester.run("no-test-global", require("../../fixtures/testers/rule-tester/no-test-global"), {
            valid: [
                "var test = 'foo'",
                "var test2 = test"
            ],
            invalid: [{ code: "bar", errors: 1, globals: { foo: true } }]
        });
    });

    it("should correctly set the globals configuration", () => {
        const config = { globals: { test: true } };

        RuleTester.setDefaultConfig(config);
        assert(
            RuleTester.getDefaultConfig().globals.test,
            "The default config object is incorrect"
        );
    });

    it("should correctly reset the global configuration", () => {
        const config = { globals: { test: true } };

        RuleTester.setDefaultConfig(config);
        RuleTester.resetDefaultConfig();
        assert.deepStrictEqual(
            RuleTester.getDefaultConfig(),
            { rules: {} },
            "The default configuration has not reset correctly"
        );
    });

    it("should enforce the global configuration to be an object", () => {

        /**
         * Set the default config for the rules tester
         * @param {Object} config configuration object
         * @returns {Function} Function to be executed
         * @private
         */
        function setConfig(config) {
            return function() {
                RuleTester.setDefaultConfig(config);
            };
        }
        assert.throw(setConfig());
        assert.throw(setConfig(1));
        assert.throw(setConfig(3.14));
        assert.throw(setConfig("foo"));
        assert.throw(setConfig(null));
        assert.throw(setConfig(true));
    });

    it("should pass-through the globals config to the tester then to the to rule", () => {
        const config = { globals: { test: true } };

        RuleTester.setDefaultConfig(config);
        ruleTester = new RuleTester();

        ruleTester.run("no-test-global", require("../../fixtures/testers/rule-tester/no-test-global"), {
            valid: [
                "var test = 'foo'",
                "var test2 = test"
            ],
            invalid: [{ code: "bar", errors: 1, globals: { foo: true } }]
        });
    });

    it("should throw an error if AST was modified", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast"), {
                valid: [
                    "var foo = 0;"
                ],
                invalid: []
            });
        }, "Rule should not modify AST.");
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast"), {
                valid: [],
                invalid: [
                    { code: "var bar = 0;", errors: ["error"] }
                ]
            });
        }, "Rule should not modify AST.");
    });

    it("should throw an error if AST was modified (at Program)", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-first"), {
                valid: [
                    "var foo = 0;"
                ],
                invalid: []
            });
        }, "Rule should not modify AST.");
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-first"), {
                valid: [],
                invalid: [
                    { code: "var bar = 0;", errors: ["error"] }
                ]
            });
        }, "Rule should not modify AST.");
    });

    it("should throw an error if AST was modified (at Program:exit)", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-last"), {
                valid: [
                    "var foo = 0;"
                ],
                invalid: []
            });
        }, "Rule should not modify AST.");
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-last"), {
                valid: [],
                invalid: [
                    { code: "var bar = 0;", errors: ["error"] }
                ]
            });
        }, "Rule should not modify AST.");
    });

    it("should throw an error if rule uses start and end properties on nodes, tokens or comments", () => {
        const usesStartEndRule = {
            create(context) {

                const sourceCode = context.getSourceCode();

                return {
                    CallExpression(node) {
                        noop(node.arguments[1].start);
                    },
                    "BinaryExpression[operator='+']"(node) {
                        noop(node.end);
                    },
                    "UnaryExpression[operator='-']"(node) {
                        noop(sourceCode.getFirstToken(node).start);
                    },
                    ConditionalExpression(node) {
                        noop(sourceCode.getFirstToken(node).end);
                    },
                    BlockStatement(node) {
                        noop(sourceCode.getCommentsInside(node)[0].start);
                    },
                    ObjectExpression(node) {
                        noop(sourceCode.getCommentsInside(node)[0].end);
                    },
                    Decorator(node) {
                        noop(node.start);
                    }
                };
            }
        };

        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: ["foo(a, b)"],
                invalid: []
            });
        }, "Use node.range[0] instead of node.start");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [],
                invalid: [{ code: "var a = b * (c + d) / e;", errors: 1 }]
            });
        }, "Use node.range[1] instead of node.end");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [],
                invalid: [{ code: "var a = -b * c;", errors: 1 }]
            });
        }, "Use token.range[0] instead of token.start");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: ["var a = b ? c : d;"],
                invalid: []
            });
        }, "Use token.range[1] instead of token.end");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: ["function f() { /* comment */ }"],
                invalid: []
            });
        }, "Use token.range[0] instead of token.start");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [],
                invalid: [{ code: "var x = //\n {\n //comment\n //\n}", errors: 1 }]
            });
        }, "Use token.range[1] instead of token.end");

        const enhancedParserPath = require.resolve("../../fixtures/parsers/enhanced-parser");

        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [{ code: "foo(a, b)", parser: enhancedParserPath }],
                invalid: []
            });
        }, "Use node.range[0] instead of node.start");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [],
                invalid: [{ code: "var a = b * (c + d) / e;", parser: enhancedParserPath, errors: 1 }]
            });
        }, "Use node.range[1] instead of node.end");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [],
                invalid: [{ code: "var a = -b * c;", parser: enhancedParserPath, errors: 1 }]
            });
        }, "Use token.range[0] instead of token.start");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [{ code: "var a = b ? c : d;", parser: enhancedParserPath }],
                invalid: []
            });
        }, "Use token.range[1] instead of token.end");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [{ code: "function f() { /* comment */ }", parser: enhancedParserPath }],
                invalid: []
            });
        }, "Use token.range[0] instead of token.start");
        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [],
                invalid: [{ code: "var x = //\n {\n //comment\n //\n}", parser: enhancedParserPath, errors: 1 }]
            });
        }, "Use token.range[1] instead of token.end");

        assert.throws(() => {
            ruleTester.run("uses-start-end", usesStartEndRule, {
                valid: [{ code: "@foo class A {}", parser: require.resolve("../../fixtures/parsers/enhanced-parser2") }],
                invalid: []
            });
        }, "Use node.range[0] instead of node.start");
    });

    it("should throw an error if no test scenarios given", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-last"));
        }, "Test Scenarios for rule foo : Could not find test scenario object");
    });

    it("should throw an error if no acceptable test scenario object is given", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-last"), []);
        }, "Test Scenarios for rule foo is invalid:\nCould not find any valid test scenarios\nCould not find any invalid test scenarios");
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-last"), "");
        }, "Test Scenarios for rule foo : Could not find test scenario object");
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-last"), 2);
        }, "Test Scenarios for rule foo : Could not find test scenario object");
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-last"), {});
        }, "Test Scenarios for rule foo is invalid:\nCould not find any valid test scenarios\nCould not find any invalid test scenarios");
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-last"), {
                valid: []
            });
        }, "Test Scenarios for rule foo is invalid:\nCould not find any invalid test scenarios");
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/modify-ast-at-last"), {
                invalid: []
            });
        }, "Test Scenarios for rule foo is invalid:\nCould not find any valid test scenarios");
    });

    // Nominal message/messageId use cases
    it("should assert match if message provided in both test and result.", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/messageId").withMessageOnly, {
                valid: [],
                invalid: [{ code: "foo", errors: [{ message: "something" }] }]
            });
        }, /Avoid using variables named/u);

        ruleTester.run("foo", require("../../fixtures/testers/rule-tester/messageId").withMessageOnly, {
            valid: [],
            invalid: [{ code: "foo", errors: [{ message: "Avoid using variables named 'foo'." }] }]
        });
    });

    it("should assert match between messageId if provided in both test and result.", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/messageId").withMetaWithData, {
                valid: [],
                invalid: [{ code: "foo", errors: [{ messageId: "unused" }] }]
            });
        }, "messageId 'avoidFoo' does not match expected messageId 'unused'.");

        ruleTester.run("foo", require("../../fixtures/testers/rule-tester/messageId").withMetaWithData, {
            valid: [],
            invalid: [{ code: "foo", errors: [{ messageId: "avoidFoo" }] }]
        });
    });
    it("should assert match between resulting message output if messageId and data provided in both test and result", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/messageId").withMetaWithData, {
                valid: [],
                invalid: [{ code: "foo", errors: [{ messageId: "avoidFoo", data: { name: "notFoo" } }] }]
            });
        }, "Hydrated message \"Avoid using variables named 'notFoo'.\" does not match \"Avoid using variables named 'foo'.\"");
    });

    // messageId/message misconfiguration cases
    it("should throw if user tests for both message and messageId", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/messageId").withMetaWithData, {
                valid: [],
                invalid: [{ code: "foo", errors: [{ message: "something", messageId: "avoidFoo" }] }]
            });
        }, "Error should not specify both 'message' and a 'messageId'.");
    });
    it("should throw if user tests for messageId but the rule doesn't use the messageId meta syntax.", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/messageId").withMessageOnly, {
                valid: [],
                invalid: [{ code: "foo", errors: [{ messageId: "avoidFoo" }] }]
            });
        }, "Error can not use 'messageId' if rule under test doesn't define 'meta.messages'");
    });
    it("should throw if user tests for messageId not listed in the rule's meta syntax.", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/messageId").withMetaWithData, {
                valid: [],
                invalid: [{ code: "foo", errors: [{ messageId: "useFoo" }] }]
            });
        }, /Invalid messageId 'useFoo'/u);
    });
    it("should throw if data provided without messageId.", () => {
        assert.throws(() => {
            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/messageId").withMetaWithData, {
                valid: [],
                invalid: [{ code: "foo", errors: [{ data: "something" }] }]
            });
        }, "Error must specify 'messageId' if 'data' is used.");
    });

    // fixable rules with or without `meta` property
    it("should not throw an error if a rule that has `meta.fixable` produces fixes", () => {
        const replaceProgramWith5Rule = {
            meta: {
                fixable: "code"
            },
            create(context) {
                return {
                    Program(node) {
                        context.report({ node, message: "bad", fix: fixer => fixer.replaceText(node, "5") });
                    }
                };
            }
        };

        ruleTester.run("replaceProgramWith5", replaceProgramWith5Rule, {
            valid: [],
            invalid: [
                { code: "var foo = bar;", output: "5", errors: 1 }
            ]
        });
    });
    it("should throw an error if a new-format rule that doesn't have `meta` produces fixes", () => {
        const replaceProgramWith5Rule = {
            create(context) {
                return {
                    Program(node) {
                        context.report({ node, message: "bad", fix: fixer => fixer.replaceText(node, "5") });
                    }
                };
            }
        };

        assert.throws(() => {
            ruleTester.run("replaceProgramWith5", replaceProgramWith5Rule, {
                valid: [],
                invalid: [
                    { code: "var foo = bar;", output: "5", errors: 1 }
                ]
            });
        }, "Fixable rules should export a `meta.fixable` property.");
    });
    it("should throw an error if a legacy-format rule produces fixes", () => {

        /**
         * Legacy-format rule (a function instead of an object with `create` method).
         * @param {RuleContext} context The ESLint rule context object.
         * @returns {Object} Listeners.
         */
        function replaceProgramWith5Rule(context) {
            return {
                Program(node) {
                    context.report({ node, message: "bad", fix: fixer => fixer.replaceText(node, "5") });
                }
            };
        }

        assert.throws(() => {
            ruleTester.run("replaceProgramWith5", replaceProgramWith5Rule, {
                valid: [],
                invalid: [
                    { code: "var foo = bar;", output: "5", errors: 1 }
                ]
            });
        }, "Fixable rules should export a `meta.fixable` property.");
    });

    describe("suggestions", () => {
        it("should pass with valid suggestions (tested using desc)", () => {
            ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/suggestions").basic, {
                valid: [
                    "var boo;"
                ],
                invalid: [{
                    code: "var foo;",
                    errors: [{
                        suggestions: [{
                            desc: "Rename identifier 'foo' to 'bar'",
                            output: "var bar;"
                        }]
                    }]
                }]
            });
        });

        it("should pass with suggestions on multiple lines", () => {
            ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/suggestions").basic, {
                valid: [],
                invalid: [
                    {
                        code: "function foo() {\n  var foo = 1;\n}",
                        errors: [{
                            suggestions: [{
                                desc: "Rename identifier 'foo' to 'bar'",
                                output: "function bar() {\n  var foo = 1;\n}"
                            }]
                        }, {
                            suggestions: [{
                                desc: "Rename identifier 'foo' to 'bar'",
                                output: "function foo() {\n  var bar = 1;\n}"
                            }]
                        }]
                    }
                ]
            });
        });

        it("should pass with valid suggestions (tested using messageIds)", () => {
            ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                valid: [],
                invalid: [{
                    code: "var foo;",
                    errors: [{
                        suggestions: [{
                            messageId: "renameFoo",
                            output: "var bar;"
                        }, {
                            messageId: "renameFoo",
                            output: "var baz;"
                        }]
                    }]
                }]
            });
        });

        it("should pass with valid suggestions (one tested using messageIds, the other using desc)", () => {
            ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                valid: [],
                invalid: [{
                    code: "var foo;",
                    errors: [{
                        suggestions: [{
                            messageId: "renameFoo",
                            output: "var bar;"
                        }, {
                            desc: "Rename identifier 'foo' to 'baz'",
                            output: "var baz;"
                        }]
                    }]
                }]
            });
        });

        it("should pass with valid suggestions (tested using both desc and messageIds for the same suggestion)", () => {
            ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                valid: [],
                invalid: [{
                    code: "var foo;",
                    errors: [{
                        suggestions: [{
                            desc: "Rename identifier 'foo' to 'bar'",
                            messageId: "renameFoo",
                            output: "var bar;"
                        }, {
                            desc: "Rename identifier 'foo' to 'baz'",
                            messageId: "renameFoo",
                            output: "var baz;"
                        }]
                    }]
                }]
            });
        });

        it("should pass with valid suggestions (tested using only desc on a rule that utilizes meta.messages)", () => {
            ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                valid: [],
                invalid: [{
                    code: "var foo;",
                    errors: [{
                        suggestions: [{
                            desc: "Rename identifier 'foo' to 'bar'",
                            output: "var bar;"
                        }, {
                            desc: "Rename identifier 'foo' to 'baz'",
                            output: "var baz;"
                        }]
                    }]
                }]
            });
        });

        it("should pass with valid suggestions (tested using messageIds and data)", () => {
            ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                valid: [],
                invalid: [{
                    code: "var foo;",
                    errors: [{
                        suggestions: [{
                            messageId: "renameFoo",
                            data: { newName: "bar" },
                            output: "var bar;"
                        }, {
                            messageId: "renameFoo",
                            data: { newName: "baz" },
                            output: "var baz;"
                        }]
                    }]
                }]
            });
        });


        it("should pass when tested using empty suggestion test objects if the array length is correct", () => {
            ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                valid: [],
                invalid: [{
                    code: "var foo;",
                    errors: [{
                        suggestions: [{}, {}]
                    }]
                }]
            });
        });

        it("should support explicitly expecting no suggestions", () => {
            [void 0, null, false, []].forEach(suggestions => {
                ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/no-eval"), {
                    valid: [],
                    invalid: [{
                        code: "eval('var foo');",
                        errors: [{
                            suggestions
                        }]
                    }]
                });
            });
        });

        it("should fail when expecting no suggestions and there are suggestions", () => {
            [void 0, null, false, []].forEach(suggestions => {
                assert.throws(() => {
                    ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/suggestions").basic, {
                        valid: [],
                        invalid: [{
                            code: "var foo;",
                            errors: [{
                                suggestions
                            }]
                        }]
                    });
                }, "Error should have no suggestions on error with message: \"Avoid using identifiers named 'foo'.\"");
            });
        });

        it("should fail when testing for suggestions that don't exist", () => {
            assert.throws(() => {
                ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                messageId: "this-does-not-exist"
                            }]
                        }]
                    }]
                });
            }, "Error should have an array of suggestions. Instead received \"undefined\" on error with message: \"Bad var.\"");
        });

        it("should fail when there are a different number of suggestions", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/suggestions").basic, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                desc: "Rename identifier 'foo' to 'bar'",
                                output: "var bar;"
                            }, {
                                desc: "Rename identifier 'foo' to 'baz'",
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error should have 2 suggestions. Instead found 1 suggestions");
        });

        it("should throw if the suggestion description doesn't match", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/suggestions").basic, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                desc: "not right",
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 0 : desc should be \"not right\" but got \"Rename identifier 'foo' to 'bar'\" instead.");
        });

        it("should throw if the suggestion description doesn't match (although messageIds match)", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                desc: "Rename identifier 'foo' to 'bar'",
                                messageId: "renameFoo",
                                output: "var bar;"
                            }, {
                                desc: "Rename id 'foo' to 'baz'",
                                messageId: "renameFoo",
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 1 : desc should be \"Rename id 'foo' to 'baz'\" but got \"Rename identifier 'foo' to 'baz'\" instead.");
        });

        it("should throw if the suggestion messageId doesn't match", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                messageId: "unused",
                                output: "var bar;"
                            }, {
                                messageId: "renameFoo",
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 0 : messageId should be 'unused' but got 'renameFoo' instead.");
        });

        it("should throw if the suggestion messageId doesn't match (although descriptions match)", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                desc: "Rename identifier 'foo' to 'bar'",
                                messageId: "renameFoo",
                                output: "var bar;"
                            }, {
                                desc: "Rename identifier 'foo' to 'baz'",
                                messageId: "avoidFoo",
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 1 : messageId should be 'avoidFoo' but got 'renameFoo' instead.");
        });

        it("should throw if test specifies messageId for a rule that doesn't have meta.messages", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/suggestions").basic, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                messageId: "renameFoo",
                                output: "var bar;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 0 : Test can not use 'messageId' if rule under test doesn't define 'meta.messages'.");
        });

        it("should throw if test specifies messageId that doesn't exist in the rule's meta.messages", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                messageId: "renameFoo",
                                output: "var bar;"
                            }, {
                                messageId: "removeFoo",
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 1 : Test has invalid messageId 'removeFoo', the rule under test allows only one of ['avoidFoo', 'unused', 'renameFoo'].");
        });

        it("should throw if hydrated desc doesn't match (wrong data value)", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                messageId: "renameFoo",
                                data: { newName: "car" },
                                output: "var bar;"
                            }, {
                                messageId: "renameFoo",
                                data: { newName: "baz" },
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 0 : Hydrated test desc \"Rename identifier 'foo' to 'car'\" does not match received desc \"Rename identifier 'foo' to 'bar'\".");
        });

        it("should throw if hydrated desc doesn't match (wrong data key)", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                messageId: "renameFoo",
                                data: { newName: "bar" },
                                output: "var bar;"
                            }, {
                                messageId: "renameFoo",
                                data: { name: "baz" },
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 1 : Hydrated test desc \"Rename identifier 'foo' to '{{ newName }}'\" does not match received desc \"Rename identifier 'foo' to 'baz'\".");
        });

        it("should throw if test specifies both desc and data", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                desc: "Rename identifier 'foo' to 'bar'",
                                messageId: "renameFoo",
                                data: { newName: "bar" },
                                output: "var bar;"
                            }, {
                                messageId: "renameFoo",
                                data: { newName: "baz" },
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 0 : Test should not specify both 'desc' and 'data'.");
        });

        it("should throw if test uses data but doesn't specify messageId", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                messageId: "renameFoo",
                                data: { newName: "bar" },
                                output: "var bar;"
                            }, {
                                data: { newName: "baz" },
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Error Suggestion at index 1 : Test must specify 'messageId' if 'data' is used.");
        });

        it("should throw if the resulting suggestion output doesn't match", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/suggestions").basic, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                desc: "Rename identifier 'foo' to 'bar'",
                                output: "var baz;"
                            }]
                        }]
                    }]
                });
            }, "Expected the applied suggestion fix to match the test suggestion output");
        });

        it("should fail when specified suggestion isn't an object", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/suggestions").basic, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [null]
                        }]
                    }]
                });
            }, "Test suggestion in 'suggestions' array must be an object.");

            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [
                                {
                                    messageId: "renameFoo",
                                    output: "var bar;"
                                },
                                "Rename identifier 'foo' to 'baz'"
                            ]
                        }]
                    }]
                });
            }, "Test suggestion in 'suggestions' array must be an object.");
        });

        it("should fail when the suggestion is an object with an unknown property name", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-basic", require("../../fixtures/testers/rule-tester/suggestions").basic, {
                    valid: [
                        "var boo;"
                    ],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                message: "Rename identifier 'foo' to 'bar'"
                            }]
                        }]
                    }]
                });
            }, /Invalid suggestion property name 'message'/u);
        });

        it("should fail when any of the suggestions is an object with an unknown property name", () => {
            assert.throws(() => {
                ruleTester.run("suggestions-messageIds", require("../../fixtures/testers/rule-tester/suggestions").withMessageIds, {
                    valid: [],
                    invalid: [{
                        code: "var foo;",
                        errors: [{
                            suggestions: [{
                                messageId: "renameFoo",
                                output: "var bar;"
                            }, {
                                messageId: "renameFoo",
                                outpt: "var baz;"
                            }]
                        }]
                    }]
                });
            }, /Invalid suggestion property name 'outpt'/u);
        });
    });

    describe("naming test cases", () => {

        /**
         * Asserts that a particular value will be emitted from an EventEmitter.
         * @param {EventEmitter} emitter The emitter that should emit a value
         * @param {string} emitType The type of emission to listen for
         * @param {*} expectedValue The value that should be emitted
         * @returns {Promise} A Promise that fulfills if the value is emitted, and rejects if something else is emitted.
         * The Promise will be indefinitely pending if no value is emitted.
         */
        function assertEmitted(emitter, emitType, expectedValue) {
            return new Promise((resolve, reject) => {
                emitter.once(emitType, emittedValue => {
                    if (emittedValue === expectedValue) {
                        resolve();
                    } else {
                        reject(new Error(`Expected ${expectedValue} to be emitted but ${emittedValue} was emitted instead.`));
                    }
                });
            });
        }

        it("should use the first argument as the name of the test suite", () => {
            const assertion = assertEmitted(ruleTesterTestEmitter, "describe", "this-is-a-rule-name");

            ruleTester.run("this-is-a-rule-name", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [],
                invalid: []
            });

            return assertion;
        });

        it("should use the test code as the name of the tests for valid code (string form)", () => {
            const assertion = assertEmitted(ruleTesterTestEmitter, "it", "valid(code);");

            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    "valid(code);"
                ],
                invalid: []
            });

            return assertion;
        });

        it("should use the test code as the name of the tests for valid code (object form)", () => {
            const assertion = assertEmitted(ruleTesterTestEmitter, "it", "valid(code);");

            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    {
                        code: "valid(code);"
                    }
                ],
                invalid: []
            });

            return assertion;
        });

        it("should use the test code as the name of the tests for invalid code", () => {
            const assertion = assertEmitted(ruleTesterTestEmitter, "it", "var x = invalid(code);");

            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [],
                invalid: [
                    {
                        code: "var x = invalid(code);",
                        output: " x = invalid(code);",
                        errors: 1
                    }
                ]
            });

            return assertion;
        });

        // https://github.com/eslint/eslint/issues/8142
        it("should use the empty string as the name of the test if the test case is an empty string", () => {
            const assertion = assertEmitted(ruleTesterTestEmitter, "it", "");

            ruleTester.run("foo", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [
                    {
                        code: ""
                    }
                ],
                invalid: []
            });

            return assertion;
        });
    });

    // https://github.com/eslint/eslint/issues/11615
    it("should fail the case if autofix made a syntax error.", () => {
        assert.throw(() => {
            ruleTester.run(
                "foo",
                context => ({
                    Identifier(node) {
                        context.report({
                            node,
                            message: "make a syntax error",
                            fix(fixer) {
                                return fixer.replaceText(node, "one two");
                            }
                        });
                    }
                }),
                {
                    valid: ["one()"],
                    invalid: []
                }
            );
        }, /A fatal parsing error occurred in autofix.\nError: .+\nAutofix output:\n.+/u);
    });

    describe("sanitize test cases", () => {
        let originalRuleTesterIt;
        let spyRuleTesterIt;

        before(() => {
            originalRuleTesterIt = RuleTester.it;
            spyRuleTesterIt = sinon.spy();
            RuleTester.it = spyRuleTesterIt;
        });
        after(() => {
            RuleTester.it = originalRuleTesterIt;
        });
        beforeEach(() => {
            spyRuleTesterIt.resetHistory();
            ruleTester = new RuleTester();
        });
        it("should present newline when using back-tick as new line", () => {
            const code = `
            var foo = bar;`;

            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [],
                invalid: [
                    {
                        code,
                        errors: [/^Bad var/u]
                    }
                ]
            });
            sinon.assert.calledWith(spyRuleTesterIt, code);
        });
        it("should present \\u0000 as a string", () => {
            const code = "\u0000";

            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [],
                invalid: [
                    {
                        code,
                        errors: [/^Bad var/u]
                    }
                ]
            });
            sinon.assert.calledWith(spyRuleTesterIt, "\\u0000");
        });
        it("should present the pipe character correctly", () => {
            const code = "var foo = bar || baz;";

            ruleTester.run("no-var", require("../../fixtures/testers/rule-tester/no-var"), {
                valid: [],
                invalid: [
                    {
                        code,
                        errors: [/^Bad var/u]
                    }
                ]
            });
            sinon.assert.calledWith(spyRuleTesterIt, code);
        });

    });

});