formaterrors/test/testHelpers/moduleLoader.js

API that provides formatting and highlight options for errors and their stack trace

var vm = require('vm');
var fs = require('fs');
var path = require('path');

/**
 * Helper for unit testing:
 * - load module with mocked dependencies
 * - allow accessing private state of the module
 *
 * @param {string} filePath Absolute path to module (file to load)
 * @param {Object=} mocks Hash of mocked dependencies
 */
exports.loadModule = function(filePath, mocks) {
    mocks = mocks || {};

    console.log(filePath);
    
    // this is necessary to allow relative path modules within loaded file
    // i.e. requiring ./some inside file /a/b.js needs to be resolved to /a/some
    var resolveModule = function(module) {
        if (module.charAt(0) !== '.') return module;
        return path.resolve(path.dirname(filePath), module);
    };

    var exports = {};
    var context = {
        require: function(name) {
            return mocks[name] || require(resolveModule(name));
        },
        console: console,
        exports: exports,
        module: {
            exports: exports
        }
    };

    vm.runInNewContext(fs.readFileSync(filePath), context);
    return context;
};