Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1015 insertions, 0 deletions

diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/helpers.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/helpers.js
new file mode 100644
index 0000000000..823242cf92
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/helpers.js
@@ -0,0 +1,1015 @@
+/**
+ * @fileoverview A collection of helper functions.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+"use strict";
+
+const parser = require("@babel/eslint-parser");
+const { analyze } = require("eslint-scope");
+const { KEYS: defaultVisitorKeys } = require("eslint-visitor-keys");
+const estraverse = require("estraverse");
+const path = require("path");
+const fs = require("fs");
+const ini = require("multi-ini");
+const recommendedConfig = require("./configs/recommended");
+
+var gRootDir = null;
+var directoryManifests = new Map();
+
+const callExpressionDefinitions = [
+  /^loader\.lazyGetter\((?:globalThis|this), "(\w+)"/,
+  /^loader\.lazyServiceGetter\((?:globalThis|this), "(\w+)"/,
+  /^loader\.lazyRequireGetter\((?:globalThis|this), "(\w+)"/,
+  /^XPCOMUtils\.defineLazyGetter\((?:globalThis|this), "(\w+)"/,
+  /^XPCOMUtils\.defineLazyModuleGetter\((?:globalThis|this), "(\w+)"/,
+  /^ChromeUtils\.defineModuleGetter\((?:globalThis|this), "(\w+)"/,
+  /^XPCOMUtils\.defineLazyPreferenceGetter\((?:globalThis|this), "(\w+)"/,
+  /^XPCOMUtils\.defineLazyProxy\((?:globalThis|this), "(\w+)"/,
+  /^XPCOMUtils\.defineLazyScriptGetter\((?:globalThis|this), "(\w+)"/,
+  /^XPCOMUtils\.defineLazyServiceGetter\((?:globalThis|this), "(\w+)"/,
+  /^XPCOMUtils\.defineConstant\((?:globalThis|this), "(\w+)"/,
+  /^DevToolsUtils\.defineLazyModuleGetter\((?:globalThis|this), "(\w+)"/,
+  /^DevToolsUtils\.defineLazyGetter\((?:globalThis|this), "(\w+)"/,
+  /^Object\.defineProperty\((?:globalThis|this), "(\w+)"/,
+  /^Reflect\.defineProperty\((?:globalThis|this), "(\w+)"/,
+  /^this\.__defineGetter__\("(\w+)"/,
+];
+
+const callExpressionMultiDefinitions = [
+  "XPCOMUtils.defineLazyGlobalGetters(this,",
+  "XPCOMUtils.defineLazyGlobalGetters(globalThis,",
+  "XPCOMUtils.defineLazyModuleGetters(this,",
+  "XPCOMUtils.defineLazyModuleGetters(globalThis,",
+  "XPCOMUtils.defineLazyServiceGetters(this,",
+  "XPCOMUtils.defineLazyServiceGetters(globalThis,",
+  "ChromeUtils.defineESModuleGetters(this,",
+  "ChromeUtils.defineESModuleGetters(globalThis,",
+  "loader.lazyRequireGetter(this,",
+  "loader.lazyRequireGetter(globalThis,",
+];
+
+const workerImportFilenameMatch = /(.*\/)*((.*?)\.jsm?)/;
+
+let xpidlData;
+
+module.exports = {
+  get iniParser() {
+    if (!this._iniParser) {
+      this._iniParser = new ini.Parser();
+    }
+    return this._iniParser;
+  },
+
+  get servicesData() {
+    return require("./services.json");
+  },
+
+  /**
+   * Obtains xpidl data from the object directory specified in the
+   * environment.
+   *
+   * @returns {Map<string, object>}
+   *   A map of interface names to the interface details.
+   */
+  get xpidlData() {
+    let xpidlDir;
+
+    if (process.env.TASK_ID && !process.env.MOZ_XPT_ARTIFACTS_DIR) {
+      throw new Error(
+        "MOZ_XPT_ARTIFACTS_DIR must be set for this rule in automation"
+      );
+    }
+    xpidlDir = process.env.MOZ_XPT_ARTIFACTS_DIR;
+
+    if (!xpidlDir && process.env.MOZ_OBJDIR) {
+      xpidlDir = `${process.env.MOZ_OBJDIR}/dist/xpt_artifacts/`;
+      if (!fs.existsSync(xpidlDir)) {
+        xpidlDir = `${process.env.MOZ_OBJDIR}/config/makefiles/xpidl/`;
+      }
+    }
+    if (!xpidlDir) {
+      throw new Error(
+        "MOZ_OBJDIR must be defined in the environment for this rule, i.e. MOZ_OBJDIR=objdir-ff ./mach ..."
+      );
+    }
+    if (xpidlData) {
+      return xpidlData;
+    }
+    let files = fs.readdirSync(`${xpidlDir}`);
+    // `Makefile` is an expected file in the directory.
+    if (files.length <= 1) {
+      throw new Error("Missing xpidl data files, maybe you need to build?");
+    }
+    xpidlData = new Map();
+    for (let file of files) {
+      if (!file.endsWith(".xpt")) {
+        continue;
+      }
+      let data = JSON.parse(fs.readFileSync(path.join(`${xpidlDir}`, file)));
+      for (let details of data) {
+        xpidlData.set(details.name, details);
+      }
+    }
+    return xpidlData;
+  },
+
+  /**
+   * Gets the abstract syntax tree (AST) of the JavaScript source code contained
+   * in sourceText. This matches the results for an eslint parser, see
+   * https://eslint.org/docs/developer-guide/working-with-custom-parsers.
+   *
+   * @param  {String} sourceText
+   *         Text containing valid JavaScript.
+   * @param  {Object} astOptions
+   *         Extra configuration to pass to the espree parser, these will override
+   *         the configuration from getPermissiveConfig().
+   * @param  {Object} configOptions
+   *         Extra options for getPermissiveConfig().
+   *
+   * @return {Object}
+   *         Returns an object containing `ast`, `scopeManager` and
+   *         `visitorKeys`
+   */
+  parseCode(sourceText, astOptions = {}, configOptions = {}) {
+    // Use a permissive config file to allow parsing of anything that Espree
+    // can parse.
+    let config = { ...this.getPermissiveConfig(configOptions), ...astOptions };
+
+    let parseResult =
+      "parseForESLint" in parser
+        ? parser.parseForESLint(sourceText, config)
+        : { ast: parser.parse(sourceText, config) };
+
+    let visitorKeys = parseResult.visitorKeys || defaultVisitorKeys;
+    visitorKeys.ExperimentalRestProperty = visitorKeys.RestElement;
+    visitorKeys.ExperimentalSpreadProperty = visitorKeys.SpreadElement;
+
+    return {
+      ast: parseResult.ast,
+      scopeManager: parseResult.scopeManager || analyze(parseResult.ast),
+      visitorKeys,
+    };
+  },
+
+  /**
+   * A simplistic conversion of some AST nodes to a standard string form.
+   *
+   * @param  {Object} node
+   *         The AST node to convert.
+   *
+   * @return {String}
+   *         The JS source for the node.
+   */
+  getASTSource(node, context) {
+    switch (node.type) {
+      case "MemberExpression":
+        if (node.computed) {
+          let filename = context && context.getFilename();
+          throw new Error(
+            `getASTSource unsupported computed MemberExpression in ${filename}`
+          );
+        }
+        return (
+          this.getASTSource(node.object) +
+          "." +
+          this.getASTSource(node.property)
+        );
+      case "ThisExpression":
+        return "this";
+      case "Identifier":
+        return node.name;
+      case "Literal":
+        return JSON.stringify(node.value);
+      case "CallExpression":
+        var args = node.arguments.map(a => this.getASTSource(a)).join(", ");
+        return this.getASTSource(node.callee) + "(" + args + ")";
+      case "ObjectExpression":
+        return "{}";
+      case "ExpressionStatement":
+        return this.getASTSource(node.expression) + ";";
+      case "FunctionExpression":
+        return "function() {}";
+      case "ArrayExpression":
+        return "[" + node.elements.map(this.getASTSource, this).join(",") + "]";
+      case "ArrowFunctionExpression":
+        return "() => {}";
+      case "AssignmentExpression":
+        return (
+          this.getASTSource(node.left) + " = " + this.getASTSource(node.right)
+        );
+      case "BinaryExpression":
+        return (
+          this.getASTSource(node.left) +
+          " " +
+          node.operator +
+          " " +
+          this.getASTSource(node.right)
+        );
+      case "UnaryExpression":
+        return node.operator + " " + this.getASTSource(node.argument);
+      default:
+        throw new Error("getASTSource unsupported node type: " + node.type);
+    }
+  },
+
+  /**
+   * This walks an AST in a manner similar to ESLint passing node events to the
+   * listener. The listener is expected to be a simple function
+   * which accepts node type, node and parents arguments.
+   *
+   * @param  {Object} ast
+   *         The AST to walk.
+   * @param  {Array} visitorKeys
+   *         The visitor keys to use for the AST.
+   * @param  {Function} listener
+   *         A callback function to call for the nodes. Passed three arguments,
+   *         event type, node and an array of parent nodes for the current node.
+   */
+  walkAST(ast, visitorKeys, listener) {
+    let parents = [];
+
+    estraverse.traverse(ast, {
+      enter(node, parent) {
+        listener(node.type, node, parents);
+
+        parents.push(node);
+      },
+
+      leave(node, parent) {
+        if (!parents.length) {
+          throw new Error("Left more nodes than entered.");
+        }
+        parents.pop();
+      },
+
+      keys: visitorKeys,
+    });
+    if (parents.length) {
+      throw new Error("Entered more nodes than left.");
+    }
+  },
+
+  /**
+   * Attempts to convert an ExpressionStatement to likely global variable
+   * definitions.
+   *
+   * @param  {Object} node
+   *         The AST node to convert.
+   * @param  {boolean} isGlobal
+   *         True if the current node is in the global scope.
+   *
+   * @return {Array}
+   *         An array of objects that contain details about the globals:
+   *         - {String} name
+   *                    The name of the global.
+   *         - {Boolean} writable
+   *                     If the global is writeable or not.
+   */
+  convertWorkerExpressionToGlobals(node, isGlobal, dirname) {
+    var getGlobalsForFile = require("./globals").getGlobalsForFile;
+
+    let results = [];
+    let expr = node.expression;
+
+    if (
+      node.expression.type === "CallExpression" &&
+      expr.callee &&
+      expr.callee.type === "Identifier" &&
+      expr.callee.name === "importScripts"
+    ) {
+      for (var arg of expr.arguments) {
+        var match = arg.value && arg.value.match(workerImportFilenameMatch);
+        if (match) {
+          if (!match[1]) {
+            let filePath = path.resolve(dirname, match[2]);
+            if (fs.existsSync(filePath)) {
+              let additionalGlobals = getGlobalsForFile(filePath);
+              results = results.concat(additionalGlobals);
+            }
+          }
+          // Import with relative/absolute path should explicitly use
+          // `import-globals-from` comment.
+        }
+      }
+    }
+
+    return results;
+  },
+
+  /**
+   * Attempts to convert an AssignmentExpression into a global variable
+   * definition if it applies to `this` in the global scope.
+   *
+   * @param  {Object} node
+   *         The AST node to convert.
+   * @param  {boolean} isGlobal
+   *         True if the current node is in the global scope.
+   *
+   * @return {Array}
+   *         An array of objects that contain details about the globals:
+   *         - {String} name
+   *                    The name of the global.
+   *         - {Boolean} writable
+   *                     If the global is writeable or not.
+   */
+  convertThisAssignmentExpressionToGlobals(node, isGlobal) {
+    if (
+      isGlobal &&
+      node.expression.left &&
+      node.expression.left.object &&
+      node.expression.left.object.type === "ThisExpression" &&
+      node.expression.left.property &&
+      node.expression.left.property.type === "Identifier"
+    ) {
+      return [{ name: node.expression.left.property.name, writable: true }];
+    }
+    return [];
+  },
+
+  /**
+   * Attempts to convert an CallExpressions that look like module imports
+   * into global variable definitions.
+   *
+   * @param  {Object} node
+   *         The AST node to convert.
+   * @param  {boolean} isGlobal
+   *         True if the current node is in the global scope.
+   *
+   * @return {Array}
+   *         An array of objects that contain details about the globals:
+   *         - {String} name
+   *                    The name of the global.
+   *         - {Boolean} writable
+   *                     If the global is writeable or not.
+   */
+  convertCallExpressionToGlobals(node, isGlobal) {
+    let express = node.expression;
+    if (
+      express.type === "CallExpression" &&
+      express.callee.type === "MemberExpression" &&
+      express.callee.object &&
+      express.callee.object.type === "Identifier" &&
+      express.arguments.length === 1 &&
+      express.arguments[0].type === "ArrayExpression" &&
+      express.callee.property.type === "Identifier" &&
+      express.callee.property.name === "importGlobalProperties"
+    ) {
+      return express.arguments[0].elements.map(literal => {
+        return {
+          explicit: true,
+          name: literal.value,
+          writable: false,
+        };
+      });
+    }
+
+    let source;
+    try {
+      source = this.getASTSource(node);
+    } catch (e) {
+      return [];
+    }
+
+    // The definition matches below must be in the global scope for us to define
+    // a global, so bail out early if we're not a global.
+    if (!isGlobal) {
+      return [];
+    }
+
+    for (let reg of callExpressionDefinitions) {
+      let match = source.match(reg);
+      if (match) {
+        return [{ name: match[1], writable: true, explicit: true }];
+      }
+    }
+
+    if (
+      callExpressionMultiDefinitions.some(expr => source.startsWith(expr)) &&
+      node.expression.arguments[1]
+    ) {
+      let arg = node.expression.arguments[1];
+      if (arg.type === "ObjectExpression") {
+        return arg.properties
+          .map(p => ({
+            name: p.type === "Property" && p.key.name,
+            writable: true,
+            explicit: true,
+          }))
+          .filter(g => g.name);
+      }
+      if (arg.type === "ArrayExpression") {
+        return arg.elements
+          .map(p => ({
+            name: p.type === "Literal" && p.value,
+            writable: true,
+            explicit: true,
+          }))
+          .filter(g => typeof g.name == "string");
+      }
+    }
+
+    if (
+      node.expression.callee.type == "MemberExpression" &&
+      node.expression.callee.property.type == "Identifier" &&
+      node.expression.callee.property.name == "defineLazyScriptGetter"
+    ) {
+      // The case where we have a single symbol as a string has already been
+      // handled by the regexp, so we have an array of symbols here.
+      return node.expression.arguments[1].elements.map(n => ({
+        name: n.value,
+        writable: true,
+        explicit: true,
+      }));
+    }
+
+    return [];
+  },
+
+  /**
+   * Add a variable to the current scope.
+   * HACK: This relies on eslint internals so it could break at any time.
+   *
+   * @param {String} name
+   *        The variable name to add to the scope.
+   * @param {ASTScope} scope
+   *        The scope to add to.
+   * @param {boolean} writable
+   *        Whether the global can be overwritten.
+   * @param {Object} [node]
+   *        The AST node that defined the globals.
+   */
+  addVarToScope(name, scope, writable, node) {
+    scope.__defineGeneric(name, scope.set, scope.variables, null, null);
+
+    let variable = scope.set.get(name);
+    variable.eslintExplicitGlobal = false;
+    variable.writeable = writable;
+    if (node) {
+      variable.defs.push({
+        type: "Variable",
+        node,
+        name: { name, parent: node.parent },
+      });
+      variable.identifiers.push(node);
+    }
+
+    // Walk to the global scope which holds all undeclared variables.
+    while (scope.type != "global") {
+      scope = scope.upper;
+    }
+
+    // "through" contains all references with no found definition.
+    scope.through = scope.through.filter(function(reference) {
+      if (reference.identifier.name != name) {
+        return true;
+      }
+
+      // Links the variable and the reference.
+      // And this reference is removed from `Scope#through`.
+      reference.resolved = variable;
+      variable.references.push(reference);
+      return false;
+    });
+  },
+
+  /**
+   * Adds a set of globals to a scope.
+   *
+   * @param {Array} globalVars
+   *        An array of global variable names.
+   * @param {ASTScope} scope
+   *        The scope.
+   * @param {Object} [node]
+   *        The AST node that defined the globals.
+   */
+  addGlobals(globalVars, scope, node) {
+    globalVars.forEach(v =>
+      this.addVarToScope(v.name, scope, v.writable, v.explicit && node)
+    );
+  },
+
+  /**
+   * To allow espree to parse almost any JavaScript we need as many features as
+   * possible turned on. This method returns that config.
+   *
+   * @param {Object} options
+   *        {
+   *          useBabel: {boolean} whether to set babelOptions.
+   *        }
+   * @return {Object}
+   *         Espree compatible permissive config.
+   */
+  getPermissiveConfig({ useBabel = true } = {}) {
+    const config = {
+      range: true,
+      requireConfigFile: false,
+      babelOptions: {
+        // configFile: path.join(gRootDir, ".babel-eslint.rc.js"),
+        // parserOpts: {
+        //   plugins: [
+        //     "@babel/plugin-proposal-class-static-block",
+        //     "@babel/plugin-syntax-class-properties",
+        //     "@babel/plugin-syntax-jsx",
+        //   ],
+        // },
+      },
+      loc: true,
+      comment: true,
+      attachComment: true,
+      ecmaVersion: this.getECMAVersion(),
+      sourceType: "script",
+    };
+
+    if (useBabel && this.isMozillaCentralBased()) {
+      config.babelOptions.configFile = path.join(
+        gRootDir,
+        ".babel-eslint.rc.js"
+      );
+    }
+    return config;
+  },
+
+  /**
+   * Returns the ECMA version of the recommended config.
+   *
+   * @return {Number} The ECMA version of the recommended config.
+   */
+  getECMAVersion() {
+    return recommendedConfig.parserOptions.ecmaVersion;
+  },
+
+  /**
+   * Check whether it's inside top-level script.
+   *
+   * @param {Array} ancestors
+   *        The parents of the current node.
+   *
+   * @return {Boolean}
+   *         True or false
+   */
+  getIsTopLevelScript(ancestors) {
+    for (let parent of ancestors) {
+      switch (parent.type) {
+        case "ArrowFunctionExpression":
+        case "FunctionDeclaration":
+        case "FunctionExpression":
+        case "PropertyDefinition":
+        case "StaticBlock":
+          return false;
+      }
+    }
+    return true;
+  },
+
+  isTopLevel(ancestors) {
+    for (let parent of ancestors) {
+      switch (parent.type) {
+        case "ArrowFunctionExpression":
+        case "FunctionDeclaration":
+        case "FunctionExpression":
+        case "PropertyDefinition":
+        case "StaticBlock":
+        case "BlockStatement":
+          return false;
+      }
+    }
+    return true;
+  },
+
+  /**
+   * Check whether `this` expression points the global this.
+   *
+   * @param {Array} ancestors
+   *        The parents of the current node.
+   *
+   * @return {Boolean}
+   *         True or false
+   */
+  getIsGlobalThis(ancestors) {
+    for (let parent of ancestors) {
+      switch (parent.type) {
+        case "FunctionDeclaration":
+        case "FunctionExpression":
+        case "PropertyDefinition":
+        case "StaticBlock":
+          return false;
+      }
+    }
+    return true;
+  },
+
+  /**
+   * Check whether the node is evaluated at top-level script unconditionally.
+   *
+   * @param {Array} ancestors
+   *        The parents of the current node.
+   *
+   * @return {Boolean}
+   *         True or false
+   */
+  getIsTopLevelAndUnconditionallyExecuted(ancestors) {
+    for (let parent of ancestors) {
+      switch (parent.type) {
+        // Control flow
+        case "IfStatement":
+        case "SwitchStatement":
+        case "TryStatement":
+        case "WhileStatement":
+        case "DoWhileStatement":
+        case "ForStatement":
+        case "ForInStatement":
+        case "ForOfStatement":
+          return false;
+
+        // Function
+        case "FunctionDeclaration":
+        case "FunctionExpression":
+        case "ArrowFunctionExpression":
+        case "ClassBody":
+          return false;
+
+        // Branch
+        case "LogicalExpression":
+        case "ConditionalExpression":
+        case "ChainExpression":
+          return false;
+
+        case "AssignmentExpression":
+          switch (parent.operator) {
+            // Branch
+            case "||=":
+            case "&&=":
+            case "??=":
+              return false;
+          }
+          break;
+
+        // Implicit branch (default value)
+        case "ObjectPattern":
+        case "ArrayPattern":
+          return false;
+      }
+    }
+    return true;
+  },
+
+  /**
+   * Check whether we might be in a test head file.
+   *
+   * @param  {RuleContext} scope
+   *         You should pass this from within a rule
+   *         e.g. helpers.getIsHeadFile(context)
+   *
+   * @return {Boolean}
+   *         True or false
+   */
+  getIsHeadFile(scope) {
+    var pathAndFilename = this.cleanUpPath(scope.getFilename());
+
+    return /.*[\\/]head(_.+)?\.js$/.test(pathAndFilename);
+  },
+
+  /**
+   * Gets the head files for a potential test file
+   *
+   * @param  {RuleContext} scope
+   *         You should pass this from within a rule
+   *         e.g. helpers.getIsHeadFile(context)
+   *
+   * @return {String[]}
+   *         Paths to head files to load for the test
+   */
+  getTestHeadFiles(scope) {
+    if (!this.getIsTest(scope)) {
+      return [];
+    }
+
+    let filepath = this.cleanUpPath(scope.getFilename());
+    let dir = path.dirname(filepath);
+
+    let names = fs
+      .readdirSync(dir)
+      .filter(
+        name =>
+          (name.startsWith("head") || name.startsWith("xpcshell-head")) &&
+          name.endsWith(".js")
+      )
+      .map(name => path.join(dir, name));
+    return names;
+  },
+
+  /**
+   * Gets all the test manifest data for a directory
+   *
+   * @param  {String} dir
+   *         The directory
+   *
+   * @return {Array}
+   *         An array of objects with file and manifest properties
+   */
+  getManifestsForDirectory(dir) {
+    if (directoryManifests.has(dir)) {
+      return directoryManifests.get(dir);
+    }
+
+    let manifests = [];
+    let names = [];
+    try {
+      names = fs.readdirSync(dir);
+    } catch (err) {
+      // Ignore directory not found, it might be faked by a test
+      if (err.code !== "ENOENT") {
+        throw err;
+      }
+    }
+
+    for (let name of names) {
+      if (!name.endsWith(".ini")) {
+        continue;
+      }
+
+      try {
+        let manifest = this.iniParser.parse(
+          fs.readFileSync(path.join(dir, name), "utf8").split("\n")
+        );
+        manifests.push({
+          file: path.join(dir, name),
+          manifest,
+        });
+      } catch (e) {}
+    }
+
+    directoryManifests.set(dir, manifests);
+    return manifests;
+  },
+
+  /**
+   * Gets the manifest file a test is listed in
+   *
+   * @param  {RuleContext} scope
+   *         You should pass this from within a rule
+   *         e.g. helpers.getIsHeadFile(context)
+   *
+   * @return {String}
+   *         The path to the test manifest file
+   */
+  getTestManifest(scope) {
+    let filepath = this.cleanUpPath(scope.getFilename());
+
+    let dir = path.dirname(filepath);
+    let filename = path.basename(filepath);
+
+    for (let manifest of this.getManifestsForDirectory(dir)) {
+      if (filename in manifest.manifest) {
+        return manifest.file;
+      }
+    }
+
+    return null;
+  },
+
+  /**
+   * Check whether we are in a test of some kind.
+   *
+   * @param  {RuleContext} scope
+   *         You should pass this from within a rule
+   *         e.g. helpers.getIsTest(context)
+   *
+   * @return {Boolean}
+   *         True or false
+   */
+  getIsTest(scope) {
+    // Regardless of the manifest name being in a manifest means we're a test.
+    let manifest = this.getTestManifest(scope);
+    if (manifest) {
+      return true;
+    }
+
+    return !!this.getTestType(scope);
+  },
+
+  /*
+   * Check if this is an .sjs file.
+   */
+  getIsSjs(scope) {
+    let filepath = this.cleanUpPath(scope.getFilename());
+
+    return path.extname(filepath) == ".sjs";
+  },
+
+  /**
+   * Gets the type of test or null if this isn't a test.
+   *
+   * @param  {RuleContext} scope
+   *         You should pass this from within a rule
+   *         e.g. helpers.getIsHeadFile(context)
+   *
+   * @return {String or null}
+   *         Test type: xpcshell, browser, chrome, mochitest
+   */
+  getTestType(scope) {
+    let testTypes = ["browser", "xpcshell", "chrome", "mochitest", "a11y"];
+    let manifest = this.getTestManifest(scope);
+    if (manifest) {
+      let name = path.basename(manifest);
+      for (let testType of testTypes) {
+        if (name.startsWith(testType)) {
+          return testType;
+        }
+      }
+    }
+
+    let filepath = this.cleanUpPath(scope.getFilename());
+    let filename = path.basename(filepath);
+
+    if (filename.startsWith("browser_")) {
+      return "browser";
+    }
+
+    if (filename.startsWith("test_")) {
+      let parent = path.basename(path.dirname(filepath));
+      for (let testType of testTypes) {
+        if (parent.startsWith(testType)) {
+          return testType;
+        }
+      }
+
+      // It likely is a test, we're just not sure what kind.
+      return "unknown";
+    }
+
+    // Likely not a test
+    return null;
+  },
+
+  getIsWorker(filePath) {
+    let filename = path.basename(this.cleanUpPath(filePath)).toLowerCase();
+
+    return filename.includes("worker");
+  },
+
+  /**
+   * Gets the root directory of the repository by walking up directories from
+   * this file until a .eslintignore file is found. If this fails, the same
+   * procedure will be attempted from the current working dir.
+   * @return {String} The absolute path of the repository directory
+   */
+  get rootDir() {
+    if (!gRootDir) {
+      function searchUpForIgnore(dirName, filename) {
+        let parsed = path.parse(dirName);
+        while (parsed.root !== dirName) {
+          if (fs.existsSync(path.join(dirName, filename))) {
+            return dirName;
+          }
+          // Move up a level
+          dirName = parsed.dir;
+          parsed = path.parse(dirName);
+        }
+        return null;
+      }
+
+      let possibleRoot = searchUpForIgnore(
+        path.dirname(module.filename),
+        ".eslintignore"
+      );
+      if (!possibleRoot) {
+        possibleRoot = searchUpForIgnore(path.resolve(), ".eslintignore");
+      }
+      if (!possibleRoot) {
+        possibleRoot = searchUpForIgnore(path.resolve(), "package.json");
+      }
+      if (!possibleRoot) {
+        // We've couldn't find a root from the module or CWD, so lets just go
+        // for the CWD. We really don't want to throw if possible, as that
+        // tends to give confusing results when used with ESLint.
+        possibleRoot = process.cwd();
+      }
+
+      gRootDir = possibleRoot;
+    }
+
+    return gRootDir;
+  },
+
+  /**
+   * ESLint may be executed from various places: from mach, at the root of the
+   * repository, or from a directory in the repository when, for instance,
+   * executed by a text editor's plugin.
+   * The value returned by context.getFileName() varies because of this.
+   * This helper function makes sure to return an absolute file path for the
+   * current context, by looking at process.cwd().
+   * @param {Context} context
+   * @return {String} The absolute path
+   */
+  getAbsoluteFilePath(context) {
+    var fileName = this.cleanUpPath(context.getFilename());
+    var cwd = process.cwd();
+
+    if (path.isAbsolute(fileName)) {
+      // Case 2: executed from the repo's root with mach:
+      //   fileName: /path/to/mozilla/repo/a/b/c/d.js
+      //   cwd: /path/to/mozilla/repo
+      return fileName;
+    } else if (path.basename(fileName) == fileName) {
+      // Case 1b: executed from a nested directory, fileName is the base name
+      // without any path info (happens in Atom with linter-eslint)
+      return path.join(cwd, fileName);
+    }
+    // Case 1: executed form in a nested directory, e.g. from a text editor:
+    //   fileName: a/b/c/d.js
+    //   cwd: /path/to/mozilla/repo/a/b/c
+    var dirName = path.dirname(fileName);
+    return cwd.slice(0, cwd.length - dirName.length) + fileName;
+  },
+
+  /**
+   * When ESLint is run from SublimeText, paths retrieved from
+   * context.getFileName contain leading and trailing double-quote characters.
+   * These characters need to be removed.
+   */
+  cleanUpPath(pathName) {
+    return pathName.replace(/^"/, "").replace(/"$/, "");
+  },
+
+  get globalScriptPaths() {
+    return [
+      path.join(this.rootDir, "browser", "base", "content", "browser.xhtml"),
+      path.join(
+        this.rootDir,
+        "browser",
+        "base",
+        "content",
+        "global-scripts.inc"
+      ),
+    ];
+  },
+
+  isMozillaCentralBased() {
+    return fs.existsSync(this.globalScriptPaths[0]);
+  },
+
+  getSavedEnvironmentItems(environment) {
+    return require("./environments/saved-globals.json").environments[
+      environment
+    ];
+  },
+
+  getSavedRuleData(rule) {
+    return require("./rules/saved-rules-data.json").rulesData[rule];
+  },
+
+  getBuildEnvironment() {
+    var { execFileSync } = require("child_process");
+    var output = execFileSync(
+      path.join(this.rootDir, "mach"),
+      ["environment", "--format=json"],
+      { silent: true }
+    );
+    return JSON.parse(output);
+  },
+
+  /**
+   * Extract the path of require (and require-like) helpers used in DevTools.
+   */
+  getDevToolsRequirePath(node) {
+    if (
+      node.callee.type == "Identifier" &&
+      node.callee.name == "require" &&
+      node.arguments.length == 1 &&
+      node.arguments[0].type == "Literal"
+    ) {
+      return node.arguments[0].value;
+    } else if (
+      node.callee.type == "MemberExpression" &&
+      node.callee.property.type == "Identifier" &&
+      node.callee.property.name == "lazyRequireGetter" &&
+      node.arguments.length >= 3 &&
+      node.arguments[2].type == "Literal"
+    ) {
+      return node.arguments[2].value;
+    }
+    return null;
+  },
+
+  /**
+   * Returns property name from MemberExpression. Also accepts Identifier for consistency.
+   * @param {import("estree").MemberExpression | import("estree").Identifier} node
+   * @returns {string | null}
+   *
+   * @example `foo` gives "foo"
+   * @example `foo.bar` gives "bar"
+   * @example `foo.bar.baz` gives "baz"
+   */
+  maybeGetMemberPropertyName(node) {
+    if (node.type === "MemberExpression") {
+      return node.property.name;
+    }
+    if (node.type === "Identifier") {
+      return node.name;
+    }
+    return null;
+  },
+};