node/tools/eslint-rules/required-modules.js

/**
 * @fileoverview Require usage of specified node modules.
 * @author Rich Trott
 */
'use strict';

const { isRequireCall, isString } = require('./rules-utils.js');

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

module.exports = {
  meta: { schema: [{
    'type': 'object',
    'additionalProperties': {
      'type': 'string',
    },
  }] },
  create(context) {
  // Trim required module names
    const options = context.options[0];
    const requiredModules = options ? Object.keys(options).map((x) => {
      return [ x, new RegExp(options[x]) ];
    }) : [];
    const isESM = context.languageOptions.sourceType === 'module';

    const foundModules = [];

    // If no modules are required we don't need to check the CallExpressions
    if (requiredModules.length === 0) {
      return {};
    }

    /**
     * Function to check if the path is a required module and return its name.
     * @param {string} str The path to check
     * @returns {undefined | string} required module name or undefined
     */
    function getRequiredModuleName(str) {
      const match = requiredModules.find(([, test]) => {
        return test.test(str);
      });
      return match ? match[0] : undefined;
    }

    /**
     * Function to check if a node has an argument that is a required module and
     * return its name.
     * @param {ASTNode} node The node to check
     * @returns {undefined | string} required module name or undefined
     */
    function getRequiredModuleNameFromCall(node) {
    // Node has arguments and first argument is string
      if (node.arguments.length && isString(node.arguments[0])) {
        return getRequiredModuleName(node.arguments[0].value.trim());
      }

      return undefined;
    }

    const rules = {
      'Program:exit'(node) {
        if (foundModules.length < requiredModules.length) {
          const missingModules = requiredModules.filter(
            ([module]) => foundModules.indexOf(module) === -1,
          );
          missingModules.forEach(([moduleName]) => {
            context.report(
              node,
              'Mandatory module "{{moduleName}}" must be loaded.',
              { moduleName: moduleName },
            );
          });
        }
      },
    };

    if (isESM) {
      rules.ImportDeclaration = (node) => {
        const requiredModuleName = getRequiredModuleName(node.source.value);
        if (requiredModuleName) {
          foundModules.push(requiredModuleName);
        }
      };
    } else {
      rules.CallExpression = (node) => {
        if (isRequireCall(node)) {
          const requiredModuleName = getRequiredModuleNameFromCall(node);

          if (requiredModuleName) {
            foundModules.push(requiredModuleName);
          }
        }
      };
    }

    return rules;
  },
};