eslint/lib/rule-tester/rule-tester.js

   1 /**
   2  * @fileoverview Mocha test wrapper
   3  * @author Ilya Volodin
   4  */
   5 "use strict";
   6
   7 /* eslint-env mocha -- Mocha wrapper */
   8
   9 /*
  10  * This is a wrapper around mocha to allow for DRY unittests for eslint
  11  * Format:
  12  * RuleTester.run("{ruleName}", {
  13  *      valid: [
  14  *          "{code}",
  15  *          { code: "{code}", options: {options}, globals: {globals}, parser: "{parser}", settings: {settings} }
  16  *      ],
  17  *      invalid: [
  18  *          { code: "{code}", errors: {numErrors} },
  19  *          { code: "{code}", errors: ["{errorMessage}"] },
  20  *          { code: "{code}", options: {options}, globals: {globals}, parser: "{parser}", settings: {settings}, errors: [{ message: "{errorMessage}", type: "{errorNodeType}"}] }
  21  *      ]
  22  *  });
  23  *
  24  * Variables:
  25  * {code} - String that represents the code to be tested
  26  * {options} - Arguments that are passed to the configurable rules.
  27  * {globals} - An object representing a list of variables that are
  28  *             registered as globals
  29  * {parser} - String representing the parser to use
  30  * {settings} - An object representing global settings for all rules
  31  * {numErrors} - If failing case doesn't need to check error message,
  32  *               this integer will specify how many errors should be
  33  *               received
  34  * {errorMessage} - Message that is returned by the rule on failure
  35  * {errorNodeType} - AST node type that is returned by they rule as
  36  *                   a cause of the failure.
  37  */
  38
  39 //------------------------------------------------------------------------------
  40 // Requirements
  41 //------------------------------------------------------------------------------
  42
  43 const
  44     assert = require("assert"),
  45     path = require("path"),
  46     util = require("util"),
  47     merge = require("lodash.merge"),
  48     equal = require("fast-deep-equal"),
  49     Traverser = require("../../lib/shared/traverser"),
  50     { getRuleOptionsSchema, validate } = require("../shared/config-validator"),
  51     { Linter, SourceCodeFixer, interpolate } = require("../linter");
  52
  53 const ajv = require("../shared/ajv")({ strictDefaults: true });
  54
  55 const espreePath = require.resolve("espree");
  56 const parserSymbol = Symbol.for("eslint.RuleTester.parser");
  57
  58 const { SourceCode } = require("../source-code");
  59
  60 //------------------------------------------------------------------------------
  61 // Typedefs
  62 //------------------------------------------------------------------------------
  63
  64 /** @typedef {import("../shared/types").Parser} Parser */
  65
  66 /* eslint-disable jsdoc/valid-types -- https://github.com/jsdoc-type-pratt-parser/jsdoc-type-pratt-parser/issues/4#issuecomment-778805577 */
  67 /**
  68  * A test case that is expected to pass lint.
  69  * @typedef {Object} ValidTestCase
  70  * @property {string} [name] Name for the test case.
  71  * @property {string} code Code for the test case.
  72  * @property {any[]} [options] Options for the test case.
  73  * @property {{ [name: string]: any }} [settings] Settings for the test case.
  74  * @property {string} [filename] The fake filename for the test case. Useful for rules that make assertion about filenames.
  75  * @property {string} [parser] The absolute path for the parser.
  76  * @property {{ [name: string]: any }} [parserOptions] Options for the parser.
  77  * @property {{ [name: string]: "readonly" | "writable" | "off" }} [globals] The additional global variables.
  78  * @property {{ [name: string]: boolean }} [env] Environments for the test case.
  79  * @property {boolean} [only] Run only this test case or the subset of test cases with this property.
  80  */
  81
  82 /**
  83  * A test case that is expected to fail lint.
  84  * @typedef {Object} InvalidTestCase
  85  * @property {string} [name] Name for the test case.
  86  * @property {string} code Code for the test case.
  87  * @property {number | Array<TestCaseError | string | RegExp>} errors Expected errors.
  88  * @property {string | null} [output] The expected code after autofixes are applied. If set to `null`, the test runner will assert that no autofix is suggested.
  89  * @property {any[]} [options] Options for the test case.
  90  * @property {{ [name: string]: any }} [settings] Settings for the test case.
  91  * @property {string} [filename] The fake filename for the test case. Useful for rules that make assertion about filenames.
  92  * @property {string} [parser] The absolute path for the parser.
  93  * @property {{ [name: string]: any }} [parserOptions] Options for the parser.
  94  * @property {{ [name: string]: "readonly" | "writable" | "off" }} [globals] The additional global variables.
  95  * @property {{ [name: string]: boolean }} [env] Environments for the test case.
  96  * @property {boolean} [only] Run only this test case or the subset of test cases with this property.
  97  */
  98
  99 /**
 100  * A description of a reported error used in a rule tester test.
 101  * @typedef {Object} TestCaseError
 102  * @property {string | RegExp} [message] Message.
 103  * @property {string} [messageId] Message ID.
 104  * @property {string} [type] The type of the reported AST node.
 105  * @property {{ [name: string]: string }} [data] The data used to fill the message template.
 106  * @property {number} [line] The 1-based line number of the reported start location.
 107  * @property {number} [column] The 1-based column number of the reported start location.
 108  * @property {number} [endLine] The 1-based line number of the reported end location.
 109  * @property {number} [endColumn] The 1-based column number of the reported end location.
 110  */
 111 /* eslint-enable jsdoc/valid-types -- https://github.com/jsdoc-type-pratt-parser/jsdoc-type-pratt-parser/issues/4#issuecomment-778805577 */
 112
 113 //------------------------------------------------------------------------------
 114 // Private Members
 115 //------------------------------------------------------------------------------
 116
 117 /*
 118  * testerDefaultConfig must not be modified as it allows to reset the tester to
 119  * the initial default configuration
 120  */
 121 const testerDefaultConfig = { rules: {} };
 122 let defaultConfig = { rules: {} };
 123
 124 /*
 125  * List every parameters possible on a test case that are not related to eslint
 126  * configuration
 127  */
 128 const RuleTesterParameters = [
 129     "name",
 130     "code",
 131     "filename",
 132     "options",
 133     "errors",
 134     "output",
 135     "only"
 136 ];
 137
 138 /*
 139  * All allowed property names in error objects.
 140  */
 141 const errorObjectParameters = new Set([
 142     "message",
 143     "messageId",
 144     "data",
 145     "type",
 146     "line",
 147     "column",
 148     "endLine",
 149     "endColumn",
 150     "suggestions"
 151 ]);
 152 const friendlyErrorObjectParameterList = `[${[...errorObjectParameters].map(key => `'${key}'`).join(", ")}]`;
 153
 154 /*
 155  * All allowed property names in suggestion objects.
 156  */
 157 const suggestionObjectParameters = new Set([
 158     "desc",
 159     "messageId",
 160     "data",
 161     "output"
 162 ]);
 163 const friendlySuggestionObjectParameterList = `[${[...suggestionObjectParameters].map(key => `'${key}'`).join(", ")}]`;
 164
 165 const hasOwnProperty = Function.call.bind(Object.hasOwnProperty);
 166
 167 /**
 168  * Clones a given value deeply.
 169  * Note: This ignores `parent` property.
 170  * @param {any} x A value to clone.
 171  * @returns {any} A cloned value.
 172  */
 173 function cloneDeeplyExcludesParent(x) {
 174     if (typeof x === "object" && x !== null) {
 175         if (Array.isArray(x)) {
 176             return x.map(cloneDeeplyExcludesParent);
 177         }
 178
 179         const retv = {};
 180
 181         for (const key in x) {
 182             if (key !== "parent" && hasOwnProperty(x, key)) {
 183                 retv[key] = cloneDeeplyExcludesParent(x[key]);
 184             }
 185         }
 186
 187         return retv;
 188     }
 189
 190     return x;
 191 }
 192
 193 /**
 194  * Freezes a given value deeply.
 195  * @param {any} x A value to freeze.
 196  * @returns {void}
 197  */
 198 function freezeDeeply(x) {
 199     if (typeof x === "object" && x !== null) {
 200         if (Array.isArray(x)) {
 201             x.forEach(freezeDeeply);
 202         } else {
 203             for (const key in x) {
 204                 if (key !== "parent" && hasOwnProperty(x, key)) {
 205                     freezeDeeply(x[key]);
 206                 }
 207             }
 208         }
 209         Object.freeze(x);
 210     }
 211 }
 212
 213 /**
 214  * Replace control characters by `\u00xx` form.
 215  * @param {string} text The text to sanitize.
 216  * @returns {string} The sanitized text.
 217  */
 218 function sanitize(text) {
 219     return text.replace(
 220         /[\u0000-\u0009\u000b-\u001a]/gu, // eslint-disable-line no-control-regex -- Escaping controls
 221         c => `\\u${c.codePointAt(0).toString(16).padStart(4, "0")}`
 222     );
 223 }
 224
 225 /**
 226  * Define `start`/`end` properties as throwing error.
 227  * @param {string} objName Object name used for error messages.
 228  * @param {ASTNode} node The node to define.
 229  * @returns {void}
 230  */
 231 function defineStartEndAsError(objName, node) {
 232     Object.defineProperties(node, {
 233         start: {
 234             get() {
 235                 throw new Error(`Use ${objName}.range[0] instead of ${objName}.start`);
 236             },
 237             configurable: true,
 238             enumerable: false
 239         },
 240         end: {
 241             get() {
 242                 throw new Error(`Use ${objName}.range[1] instead of ${objName}.end`);
 243             },
 244             configurable: true,
 245             enumerable: false
 246         }
 247     });
 248 }
 249
 250
 251 /**
 252  * Define `start`/`end` properties of all nodes of the given AST as throwing error.
 253  * @param {ASTNode} ast The root node to errorize `start`/`end` properties.
 254  * @param {Object} [visitorKeys] Visitor keys to be used for traversing the given ast.
 255  * @returns {void}
 256  */
 257 function defineStartEndAsErrorInTree(ast, visitorKeys) {
 258     Traverser.traverse(ast, { visitorKeys, enter: defineStartEndAsError.bind(null, "node") });
 259     ast.tokens.forEach(defineStartEndAsError.bind(null, "token"));
 260     ast.comments.forEach(defineStartEndAsError.bind(null, "token"));
 261 }
 262
 263 /**
 264  * Wraps the given parser in order to intercept and modify return values from the `parse` and `parseForESLint` methods, for test purposes.
 265  * In particular, to modify ast nodes, tokens and comments to throw on access to their `start` and `end` properties.
 266  * @param {Parser} parser Parser object.
 267  * @returns {Parser} Wrapped parser object.
 268  */
 269 function wrapParser(parser) {
 270
 271     if (typeof parser.parseForESLint === "function") {
 272         return {
 273             [parserSymbol]: parser,
 274             parseForESLint(...args) {
 275                 const ret = parser.parseForESLint(...args);
 276
 277                 defineStartEndAsErrorInTree(ret.ast, ret.visitorKeys);
 278                 return ret;
 279             }
 280         };
 281     }
 282
 283     return {
 284         [parserSymbol]: parser,
 285         parse(...args) {
 286             const ast = parser.parse(...args);
 287
 288             defineStartEndAsErrorInTree(ast);
 289             return ast;
 290         }
 291     };
 292 }
 293
 294 /**
 295  * Function to replace `SourceCode.prototype.getComments`.
 296  * @returns {void}
 297  * @throws {Error} Deprecation message.
 298  */
 299 function getCommentsDeprecation() {
 300     throw new Error(
 301         "`SourceCode#getComments()` is deprecated and will be removed in a future major version. Use `getCommentsBefore()`, `getCommentsAfter()`, and `getCommentsInside()` instead."
 302     );
 303 }
 304
 305 //------------------------------------------------------------------------------
 306 // Public Interface
 307 //------------------------------------------------------------------------------
 308
 309 // default separators for testing
 310 const DESCRIBE = Symbol("describe");
 311 const IT = Symbol("it");
 312 const IT_ONLY = Symbol("itOnly");
 313
 314 /**
 315  * This is `it` default handler if `it` don't exist.
 316  * @this {Mocha}
 317  * @param {string} text The description of the test case.
 318  * @param {Function} method The logic of the test case.
 319  * @throws {Error} Any error upon execution of `method`.
 320  * @returns {any} Returned value of `method`.
 321  */
 322 function itDefaultHandler(text, method) {
 323     try {
 324         return method.call(this);
 325     } catch (err) {
 326         if (err instanceof assert.AssertionError) {
 327             err.message += ` (${util.inspect(err.actual)} ${err.operator} ${util.inspect(err.expected)})`;
 328         }
 329         throw err;
 330     }
 331 }
 332
 333 /**
 334  * This is `describe` default handler if `describe` don't exist.
 335  * @this {Mocha}
 336  * @param {string} text The description of the test case.
 337  * @param {Function} method The logic of the test case.
 338  * @returns {any} Returned value of `method`.
 339  */
 340 function describeDefaultHandler(text, method) {
 341     return method.call(this);
 342 }
 343
 344 /**
 345  * Mocha test wrapper.
 346  */
 347 class RuleTester {
 348
 349     /**
 350      * Creates a new instance of RuleTester.
 351      * @param {Object} [testerConfig] Optional, extra configuration for the tester
 352      */
 353     constructor(testerConfig) {
 354
 355         /**
 356          * The configuration to use for this tester. Combination of the tester
 357          * configuration and the default configuration.
 358          * @type {Object}
 359          */
 360         this.testerConfig = merge(
 361             {},
 362             defaultConfig,
 363             testerConfig,
 364             { rules: { "rule-tester/validate-ast": "error" } }
 365         );
 366
 367         /**
 368          * Rule definitions to define before tests.
 369          * @type {Object}
 370          */
 371         this.rules = {};
 372         this.linter = new Linter();
 373     }
 374
 375     /**
 376      * Set the configuration to use for all future tests
 377      * @param {Object} config the configuration to use.
 378      * @throws {TypeError} If non-object config.
 379      * @returns {void}
 380      */
 381     static setDefaultConfig(config) {
 382         if (typeof config !== "object") {
 383             throw new TypeError("RuleTester.setDefaultConfig: config must be an object");
 384         }
 385         defaultConfig = config;
 386
 387         // Make sure the rules object exists since it is assumed to exist later
 388         defaultConfig.rules = defaultConfig.rules || {};
 389     }
 390
 391     /**
 392      * Get the current configuration used for all tests
 393      * @returns {Object} the current configuration
 394      */
 395     static getDefaultConfig() {
 396         return defaultConfig;
 397     }
 398
 399     /**
 400      * Reset the configuration to the initial configuration of the tester removing
 401      * any changes made until now.
 402      * @returns {void}
 403      */
 404     static resetDefaultConfig() {
 405         defaultConfig = merge({}, testerDefaultConfig);
 406     }
 407
 408
 409     /*
 410      * If people use `mocha test.js --watch` command, `describe` and `it` function
 411      * instances are different for each execution. So `describe` and `it` should get fresh instance
 412      * always.
 413      */
 414     static get describe() {
 415         return (
 416             this[DESCRIBE] ||
 417             (typeof describe === "function" ? describe : describeDefaultHandler)
 418         );
 419     }
 420
 421     static set describe(value) {
 422         this[DESCRIBE] = value;
 423     }
 424
 425     static get it() {
 426         return (
 427             this[IT] ||
 428             (typeof it === "function" ? it : itDefaultHandler)
 429         );
 430     }
 431
 432     static set it(value) {
 433         this[IT] = value;
 434     }
 435
 436     /**
 437      * Adds the `only` property to a test to run it in isolation.
 438      * @param {string | ValidTestCase | InvalidTestCase} item A single test to run by itself.
 439      * @returns {ValidTestCase | InvalidTestCase} The test with `only` set.
 440      */
 441     static only(item) {
 442         if (typeof item === "string") {
 443             return { code: item, only: true };
 444         }
 445
 446         return { ...item, only: true };
 447     }
 448
 449     static get itOnly() {
 450         if (typeof this[IT_ONLY] === "function") {
 451             return this[IT_ONLY];
 452         }
 453         if (typeof this[IT] === "function" && typeof this[IT].only === "function") {
 454             return Function.bind.call(this[IT].only, this[IT]);
 455         }
 456         if (typeof it === "function" && typeof it.only === "function") {
 457             return Function.bind.call(it.only, it);
 458         }
 459
 460         if (typeof this[DESCRIBE] === "function" || typeof this[IT] === "function") {
 461             throw new Error(
 462                 "Set `RuleTester.itOnly` to use `only` with a custom test framework.\n" +
 463                 "See https://eslint.org/docs/developer-guide/nodejs-api#customizing-ruletester for more."
 464             );
 465         }
 466         if (typeof it === "function") {
 467             throw new Error("The current test framework does not support exclusive tests with `only`.");
 468         }
 469         throw new Error("To use `only`, use RuleTester with a test framework that provides `it.only()` like Mocha.");
 470     }
 471
 472     static set itOnly(value) {
 473         this[IT_ONLY] = value;
 474     }
 475
 476     /**
 477      * Define a rule for one particular run of tests.
 478      * @param {string} name The name of the rule to define.
 479      * @param {Function} rule The rule definition.
 480      * @returns {void}
 481      */
 482     defineRule(name, rule) {
 483         this.rules[name] = rule;
 484     }
 485
 486     /**
 487      * Adds a new rule test to execute.
 488      * @param {string} ruleName The name of the rule to run.
 489      * @param {Function} rule The rule to test.
 490      * @param {{
 491      *   valid: (ValidTestCase | string)[],
 492      *   invalid: InvalidTestCase[]
 493      * }} test The collection of tests to run.
 494      * @throws {TypeError|Error} If non-object `test`, or if a required
 495      * scenario of the given type is missing.
 496      * @returns {void}
 497      */
 498     run(ruleName, rule, test) {
 499
 500         const testerConfig = this.testerConfig,
 501             requiredScenarios = ["valid", "invalid"],
 502             scenarioErrors = [],
 503             linter = this.linter;
 504
 505         if (!test || typeof test !== "object") {
 506             throw new TypeError(`Test Scenarios for rule ${ruleName} : Could not find test scenario object`);
 507         }
 508
 509         requiredScenarios.forEach(scenarioType => {
 510             if (!test[scenarioType]) {
 511                 scenarioErrors.push(`Could not find any ${scenarioType} test scenarios`);
 512             }
 513         });
 514
 515         if (scenarioErrors.length > 0) {
 516             throw new Error([
 517                 `Test Scenarios for rule ${ruleName} is invalid:`
 518             ].concat(scenarioErrors).join("\n"));
 519         }
 520
 521
 522         linter.defineRule(ruleName, Object.assign({}, rule, {
 523
 524             // Create a wrapper rule that freezes the `context` properties.
 525             create(context) {
 526                 freezeDeeply(context.options);
 527                 freezeDeeply(context.settings);
 528                 freezeDeeply(context.parserOptions);
 529
 530                 return (typeof rule === "function" ? rule : rule.create)(context);
 531             }
 532         }));
 533
 534         linter.defineRules(this.rules);
 535
 536         /**
 537          * Run the rule for the given item
 538          * @param {string|Object} item Item to run the rule against
 539          * @throws {Error} If an invalid schema.
 540          * @returns {Object} Eslint run result
 541          * @private
 542          */
 543         function runRuleForItem(item) {
 544             let config = merge({}, testerConfig),
 545                 code, filename, output, beforeAST, afterAST;
 546
 547             if (typeof item === "string") {
 548                 code = item;
 549             } else {
 550                 code = item.code;
 551
 552                 /*
 553                  * Assumes everything on the item is a config except for the
 554                  * parameters used by this tester
 555                  */
 556                 const itemConfig = { ...item };
 557
 558                 for (const parameter of RuleTesterParameters) {
 559                     delete itemConfig[parameter];
 560                 }
 561
 562                 /*
 563                  * Create the config object from the tester config and this item
 564                  * specific configurations.
 565                  */
 566                 config = merge(
 567                     config,
 568                     itemConfig
 569                 );
 570             }
 571
 572             if (item.filename) {
 573                 filename = item.filename;
 574             }
 575
 576             if (hasOwnProperty(item, "options")) {
 577                 assert(Array.isArray(item.options), "options must be an array");
 578                 config.rules[ruleName] = [1].concat(item.options);
 579             } else {
 580                 config.rules[ruleName] = 1;
 581             }
 582
 583             const schema = getRuleOptionsSchema(rule);
 584
 585             /*
 586              * Setup AST getters.
 587              * The goal is to check whether or not AST was modified when
 588              * running the rule under test.
 589              */
 590             linter.defineRule("rule-tester/validate-ast", () => ({
 591                 Program(node) {
 592                     beforeAST = cloneDeeplyExcludesParent(node);
 593                 },
 594                 "Program:exit"(node) {
 595                     afterAST = node;
 596                 }
 597             }));
 598
 599             if (typeof config.parser === "string") {
 600                 assert(path.isAbsolute(config.parser), "Parsers provided as strings to RuleTester must be absolute paths");
 601             } else {
 602                 config.parser = espreePath;
 603             }
 604
 605             linter.defineParser(config.parser, wrapParser(require(config.parser)));
 606
 607             if (schema) {
 608                 ajv.validateSchema(schema);
 609
 610                 if (ajv.errors) {
 611                     const errors = ajv.errors.map(error => {
 612                         const field = error.dataPath[0] === "." ? error.dataPath.slice(1) : error.dataPath;
 613
 614                         return `\t${field}: ${error.message}`;
 615                     }).join("\n");
 616
 617                     throw new Error([`Schema for rule ${ruleName} is invalid:`, errors]);
 618                 }
 619
 620                 /*
 621                  * `ajv.validateSchema` checks for errors in the structure of the schema (by comparing the schema against a "meta-schema"),
 622                  * and it reports those errors individually. However, there are other types of schema errors that only occur when compiling
 623                  * the schema (e.g. using invalid defaults in a schema), and only one of these errors can be reported at a time. As a result,
 624                  * the schema is compiled here separately from checking for `validateSchema` errors.
 625                  */
 626                 try {
 627                     ajv.compile(schema);
 628                 } catch (err) {
 629                     throw new Error(`Schema for rule ${ruleName} is invalid: ${err.message}`);
 630                 }
 631             }
 632
 633             validate(config, "rule-tester", id => (id === ruleName ? rule : null));
 634
 635             // Verify the code.
 636             const { getComments } = SourceCode.prototype;
 637             let messages;
 638
 639             try {
 640                 SourceCode.prototype.getComments = getCommentsDeprecation;
 641                 messages = linter.verify(code, config, filename);
 642             } finally {
 643                 SourceCode.prototype.getComments = getComments;
 644             }
 645
 646             const fatalErrorMessage = messages.find(m => m.fatal);
 647
 648             assert(!fatalErrorMessage, `A fatal parsing error occurred: ${fatalErrorMessage && fatalErrorMessage.message}`);
 649
 650             // Verify if autofix makes a syntax error or not.
 651             if (messages.some(m => m.fix)) {
 652                 output = SourceCodeFixer.applyFixes(code, messages).output;
 653                 const errorMessageInFix = linter.verify(output, config, filename).find(m => m.fatal);
 654
 655                 assert(!errorMessageInFix, [
 656                     "A fatal parsing error occurred in autofix.",
 657                     `Error: ${errorMessageInFix && errorMessageInFix.message}`,
 658                     "Autofix output:",
 659                     output
 660                 ].join("\n"));
 661             } else {
 662                 output = code;
 663             }
 664
 665             return {
 666                 messages,
 667                 output,
 668                 beforeAST,
 669                 afterAST: cloneDeeplyExcludesParent(afterAST)
 670             };
 671         }
 672
 673         /**
 674          * Check if the AST was changed
 675          * @param {ASTNode} beforeAST AST node before running
 676          * @param {ASTNode} afterAST AST node after running
 677          * @returns {void}
 678          * @private
 679          */
 680         function assertASTDidntChange(beforeAST, afterAST) {
 681             if (!equal(beforeAST, afterAST)) {
 682                 assert.fail("Rule should not modify AST.");
 683             }
 684         }
 685
 686         /**
 687          * Check if the template is valid or not
 688          * all valid cases go through this
 689          * @param {string|Object} item Item to run the rule against
 690          * @returns {void}
 691          * @private
 692          */
 693         function testValidTemplate(item) {
 694             const result = runRuleForItem(item);
 695             const messages = result.messages;
 696
 697             assert.strictEqual(messages.length, 0, util.format("Should have no errors but had %d: %s",
 698                 messages.length,
 699                 util.inspect(messages)));
 700
 701             assertASTDidntChange(result.beforeAST, result.afterAST);
 702         }
 703
 704         /**
 705          * Asserts that the message matches its expected value. If the expected
 706          * value is a regular expression, it is checked against the actual
 707          * value.
 708          * @param {string} actual Actual value
 709          * @param {string|RegExp} expected Expected value
 710          * @returns {void}
 711          * @private
 712          */
 713         function assertMessageMatches(actual, expected) {
 714             if (expected instanceof RegExp) {
 715
 716                 // assert.js doesn't have a built-in RegExp match function
 717                 assert.ok(
 718                     expected.test(actual),
 719                     `Expected '${actual}' to match ${expected}`
 720                 );
 721             } else {
 722                 assert.strictEqual(actual, expected);
 723             }
 724         }
 725
 726         /**
 727          * Check if the template is invalid or not
 728          * all invalid cases go through this.
 729          * @param {string|Object} item Item to run the rule against
 730          * @returns {void}
 731          * @private
 732          */
 733         function testInvalidTemplate(item) {
 734             assert.ok(item.errors || item.errors === 0,
 735                 `Did not specify errors for an invalid test of ${ruleName}`);
 736
 737             if (Array.isArray(item.errors) && item.errors.length === 0) {
 738                 assert.fail("Invalid cases must have at least one error");
 739             }
 740
 741             const ruleHasMetaMessages = hasOwnProperty(rule, "meta") && hasOwnProperty(rule.meta, "messages");
 742             const friendlyIDList = ruleHasMetaMessages ? `[${Object.keys(rule.meta.messages).map(key => `'${key}'`).join(", ")}]` : null;
 743
 744             const result = runRuleForItem(item);
 745             const messages = result.messages;
 746
 747             if (typeof item.errors === "number") {
 748
 749                 if (item.errors === 0) {
 750                     assert.fail("Invalid cases must have 'error' value greater than 0");
 751                 }
 752
 753                 assert.strictEqual(messages.length, item.errors, util.format("Should have %d error%s but had %d: %s",
 754                     item.errors,
 755                     item.errors === 1 ? "" : "s",
 756                     messages.length,
 757                     util.inspect(messages)));
 758             } else {
 759                 assert.strictEqual(
 760                     messages.length, item.errors.length, util.format(
 761                         "Should have %d error%s but had %d: %s",
 762                         item.errors.length,
 763                         item.errors.length === 1 ? "" : "s",
 764                         messages.length,
 765                         util.inspect(messages)
 766                     )
 767                 );
 768
 769                 const hasMessageOfThisRule = messages.some(m => m.ruleId === ruleName);
 770
 771                 for (let i = 0, l = item.errors.length; i < l; i++) {
 772                     const error = item.errors[i];
 773                     const message = messages[i];
 774
 775                     assert(hasMessageOfThisRule, "Error rule name should be the same as the name of the rule being tested");
 776
 777                     if (typeof error === "string" || error instanceof RegExp) {
 778
 779                         // Just an error message.
 780                         assertMessageMatches(message.message, error);
 781                     } else if (typeof error === "object" && error !== null) {
 782
 783                         /*
 784                          * Error object.
 785                          * This may have a message, messageId, data, node type, line, and/or
 786                          * column.
 787                          */
 788
 789                         Object.keys(error).forEach(propertyName => {
 790                             assert.ok(
 791                                 errorObjectParameters.has(propertyName),
 792                                 `Invalid error property name '${propertyName}'. Expected one of ${friendlyErrorObjectParameterList}.`
 793                             );
 794                         });
 795
 796                         if (hasOwnProperty(error, "message")) {
 797                             assert.ok(!hasOwnProperty(error, "messageId"), "Error should not specify both 'message' and a 'messageId'.");
 798                             assert.ok(!hasOwnProperty(error, "data"), "Error should not specify both 'data' and 'message'.");
 799                             assertMessageMatches(message.message, error.message);
 800                         } else if (hasOwnProperty(error, "messageId")) {
 801                             assert.ok(
 802                                 ruleHasMetaMessages,
 803                                 "Error can not use 'messageId' if rule under test doesn't define 'meta.messages'."
 804                             );
 805                             if (!hasOwnProperty(rule.meta.messages, error.messageId)) {
 806                                 assert(false, `Invalid messageId '${error.messageId}'. Expected one of ${friendlyIDList}.`);
 807                             }
 808                             assert.strictEqual(
 809                                 message.messageId,
 810                                 error.messageId,
 811                                 `messageId '${message.messageId}' does not match expected messageId '${error.messageId}'.`
 812                             );
 813                             if (hasOwnProperty(error, "data")) {
 814
 815                                 /*
 816                                  *  if data was provided, then directly compare the returned message to a synthetic
 817                                  *  interpolated message using the same message ID and data provided in the test.
 818                                  *  See https://github.com/eslint/eslint/issues/9890 for context.
 819                                  */
 820                                 const unformattedOriginalMessage = rule.meta.messages[error.messageId];
 821                                 const rehydratedMessage = interpolate(unformattedOriginalMessage, error.data);
 822
 823                                 assert.strictEqual(
 824                                     message.message,
 825                                     rehydratedMessage,
 826                                     `Hydrated message "${rehydratedMessage}" does not match "${message.message}"`
 827                                 );
 828                             }
 829                         }
 830
 831                         assert.ok(
 832                             hasOwnProperty(error, "data") ? hasOwnProperty(error, "messageId") : true,
 833                             "Error must specify 'messageId' if 'data' is used."
 834                         );
 835
 836                         if (error.type) {
 837                             assert.strictEqual(message.nodeType, error.type, `Error type should be ${error.type}, found ${message.nodeType}`);
 838                         }
 839
 840                         if (hasOwnProperty(error, "line")) {
 841                             assert.strictEqual(message.line, error.line, `Error line should be ${error.line}`);
 842                         }
 843
 844                         if (hasOwnProperty(error, "column")) {
 845                             assert.strictEqual(message.column, error.column, `Error column should be ${error.column}`);
 846                         }
 847
 848                         if (hasOwnProperty(error, "endLine")) {
 849                             assert.strictEqual(message.endLine, error.endLine, `Error endLine should be ${error.endLine}`);
 850                         }
 851
 852                         if (hasOwnProperty(error, "endColumn")) {
 853                             assert.strictEqual(message.endColumn, error.endColumn, `Error endColumn should be ${error.endColumn}`);
 854                         }
 855
 856                         if (hasOwnProperty(error, "suggestions")) {
 857
 858                             // Support asserting there are no suggestions
 859                             if (!error.suggestions || (Array.isArray(error.suggestions) && error.suggestions.length === 0)) {
 860                                 if (Array.isArray(message.suggestions) && message.suggestions.length > 0) {
 861                                     assert.fail(`Error should have no suggestions on error with message: "${message.message}"`);
 862                                 }
 863                             } else {
 864                                 assert.strictEqual(Array.isArray(message.suggestions), true, `Error should have an array of suggestions. Instead received "${message.suggestions}" on error with message: "${message.message}"`);
 865                                 assert.strictEqual(message.suggestions.length, error.suggestions.length, `Error should have ${error.suggestions.length} suggestions. Instead found ${message.suggestions.length} suggestions`);
 866
 867                                 error.suggestions.forEach((expectedSuggestion, index) => {
 868                                     assert.ok(
 869                                         typeof expectedSuggestion === "object" && expectedSuggestion !== null,
 870                                         "Test suggestion in 'suggestions' array must be an object."
 871                                     );
 872                                     Object.keys(expectedSuggestion).forEach(propertyName => {
 873                                         assert.ok(
 874                                             suggestionObjectParameters.has(propertyName),
 875                                             `Invalid suggestion property name '${propertyName}'. Expected one of ${friendlySuggestionObjectParameterList}.`
 876                                         );
 877                                     });
 878
 879                                     const actualSuggestion = message.suggestions[index];
 880                                     const suggestionPrefix = `Error Suggestion at index ${index} :`;
 881
 882                                     if (hasOwnProperty(expectedSuggestion, "desc")) {
 883                                         assert.ok(
 884                                             !hasOwnProperty(expectedSuggestion, "data"),
 885                                             `${suggestionPrefix} Test should not specify both 'desc' and 'data'.`
 886                                         );
 887                                         assert.strictEqual(
 888                                             actualSuggestion.desc,
 889                                             expectedSuggestion.desc,
 890                                             `${suggestionPrefix} desc should be "${expectedSuggestion.desc}" but got "${actualSuggestion.desc}" instead.`
 891                                         );
 892                                     }
 893
 894                                     if (hasOwnProperty(expectedSuggestion, "messageId")) {
 895                                         assert.ok(
 896                                             ruleHasMetaMessages,
 897                                             `${suggestionPrefix} Test can not use 'messageId' if rule under test doesn't define 'meta.messages'.`
 898                                         );
 899                                         assert.ok(
 900                                             hasOwnProperty(rule.meta.messages, expectedSuggestion.messageId),
 901                                             `${suggestionPrefix} Test has invalid messageId '${expectedSuggestion.messageId}', the rule under test allows only one of ${friendlyIDList}.`
 902                                         );
 903                                         assert.strictEqual(
 904                                             actualSuggestion.messageId,
 905                                             expectedSuggestion.messageId,
 906                                             `${suggestionPrefix} messageId should be '${expectedSuggestion.messageId}' but got '${actualSuggestion.messageId}' instead.`
 907                                         );
 908                                         if (hasOwnProperty(expectedSuggestion, "data")) {
 909                                             const unformattedMetaMessage = rule.meta.messages[expectedSuggestion.messageId];
 910                                             const rehydratedDesc = interpolate(unformattedMetaMessage, expectedSuggestion.data);
 911
 912                                             assert.strictEqual(
 913                                                 actualSuggestion.desc,
 914                                                 rehydratedDesc,
 915                                                 `${suggestionPrefix} Hydrated test desc "${rehydratedDesc}" does not match received desc "${actualSuggestion.desc}".`
 916                                             );
 917                                         }
 918                                     } else {
 919                                         assert.ok(
 920                                             !hasOwnProperty(expectedSuggestion, "data"),
 921                                             `${suggestionPrefix} Test must specify 'messageId' if 'data' is used.`
 922                                         );
 923                                     }
 924
 925                                     if (hasOwnProperty(expectedSuggestion, "output")) {
 926                                         const codeWithAppliedSuggestion = SourceCodeFixer.applyFixes(item.code, [actualSuggestion]).output;
 927
 928                                         assert.strictEqual(codeWithAppliedSuggestion, expectedSuggestion.output, `Expected the applied suggestion fix to match the test suggestion output for suggestion at index: ${index} on error with message: "${message.message}"`);
 929                                     }
 930                                 });
 931                             }
 932                         }
 933                     } else {
 934
 935                         // Message was an unexpected type
 936                         assert.fail(`Error should be a string, object, or RegExp, but found (${util.inspect(message)})`);
 937                     }
 938                 }
 939             }
 940
 941             if (hasOwnProperty(item, "output")) {
 942                 if (item.output === null) {
 943                     assert.strictEqual(
 944                         result.output,
 945                         item.code,
 946                         "Expected no autofixes to be suggested"
 947                     );
 948                 } else {
 949                     assert.strictEqual(result.output, item.output, "Output is incorrect.");
 950                 }
 951             } else {
 952                 assert.strictEqual(
 953                     result.output,
 954                     item.code,
 955                     "The rule fixed the code. Please add 'output' property."
 956                 );
 957             }
 958
 959             assertASTDidntChange(result.beforeAST, result.afterAST);
 960         }
 961
 962         /*
 963          * This creates a mocha test suite and pipes all supplied info through
 964          * one of the templates above.
 965          */
 966         RuleTester.describe(ruleName, () => {
 967             RuleTester.describe("valid", () => {
 968                 test.valid.forEach(valid => {
 969                     RuleTester[valid.only ? "itOnly" : "it"](
 970                         sanitize(typeof valid === "object" ? valid.name || valid.code : valid),
 971                         () => {
 972                             testValidTemplate(valid);
 973                         }
 974                     );
 975                 });
 976             });
 977
 978             RuleTester.describe("invalid", () => {
 979                 test.invalid.forEach(invalid => {
 980                     RuleTester[invalid.only ? "itOnly" : "it"](
 981                         sanitize(invalid.name || invalid.code),
 982                         () => {
 983                             testInvalidTemplate(invalid);
 984                         }
 985                     );
 986                 });
 987             });
 988         });
 989     }
 990 }
 991
 992 RuleTester[DESCRIBE] = RuleTester[IT] = RuleTester[IT_ONLY] = null;
 993
 994 module.exports = RuleTester;