Create Module not found error

lib/cli/config.js

@@ -11,7 +11,10 @@ const fs = require('fs');
 const path = require('path');
 const debug = require('debug')('mocha:cli:config');
 const findUp = require('find-up');
-const {createUnparsableFileError} = require('../errors');
+const {
+  createUnparsableFileError,
+  createModuleNotFoundError
+} = require('../errors');
 const utils = require('../utils');
 
 /**
@@ -82,6 +85,12 @@ exports.loadConfig = filepath => {
       config = parsers.json(filepath);
     }
   } catch (err) {
+    if (isModuleNotFoundError(err)) {
+      throw createModuleNotFoundError(
+        `${filepath} is attempting to import a module that does not exist: ${err}`,
+        filepath
+      );
+    }
     throw createUnparsableFileError(
       `Unable to read/parse ${filepath}: ${err}`,
       filepath

lib/errors.js

@@ -170,7 +170,14 @@ var constants = {
    * @constant
    * @default
    */
-  UNPARSABLE_FILE: 'ERR_MOCHA_UNPARSABLE_FILE'
+  UNPARSABLE_FILE: 'ERR_MOCHA_UNPARSABLE_FILE',
+
+  /**
+   * File attempts to import non-existent module
+   * @constant
+   * @default
+   */
+  MODULE_NOT_FOUND: 'ERR_MOCHA_MODULE_NOT_FOUND'
 };
 
 /**
@@ -516,6 +523,25 @@ function createUnparsableFileError(message, filename) {
   return err;
 }
 
+/**
+ * Creates an error object to be thrown when file attempts to import module that does not exist.
+ * @public
+ * @static
+ * @param {string} message - Error message to be displayed.
+ * @param {string} importerFilename - File name of importing module
+ * @param {string} importedFilename - File name of imported module
+ * @returns {Error} Error with code {@link constants.MODULE_NOT_FOUND}
+ */
+function createModuleNotFoundError(
+  message,
+  importerFilename,
+  importedFilename
+) {
+  var err = new Error(message);
+  err.code = constants.MODULE_NOT_FOUND;
+  return err;
+}
+
 /**
  * Returns `true` if an error came out of Mocha.
  * _Can suffer from false negatives, but not false positives._
@@ -547,6 +573,7 @@ module.exports = {
   createNoFilesMatchPatternError,
   createTimeoutError,
   createUnparsableFileError,
+  createModuleNotFoundError,
   createUnsupportedError,
   deprecate,
   isMochaError,

test/integration/config.spec.js

@@ -5,6 +5,7 @@
 
 var fs = require('fs');
 var path = require('path');
+const {constants} = require('../../lib/errors');
 var loadConfig = require('../../lib/cli/config').loadConfig;
 
 describe('config', function () {
@@ -47,6 +48,28 @@ describe('config', function () {
       expect(js, 'to equal', json);
     });
 
+    it('should throw module not found error from absolute path configuration', function () {
+      function _loadConfig() {
+        loadConfig(path.join(configDir, 'mocharcWithInvalidImport.js'));
+      }
+
+      expect(_loadConfig, 'to throw', {
+        code: constants.MODULE_NOT_FOUND
+      });
+    });
+
+    it('should throw module not found error from relative path configuration', function () {
+      var relConfigDir = configDir.substring(projRootDir.length + 1);
+
+      function _loadConfig() {
+        loadConfig(path.join('.', relConfigDir, 'mocharcWithInvalidImport.js'));
+      }
+
+      expect(_loadConfig, 'to throw', {
+        code: constants.MODULE_NOT_FOUND
+      });
+    });
+
     it('should rethrow error from absolute path configuration', function () {
       function _loadConfig() {
         loadConfig(path.join(configDir, 'mocharcWithThrowError.js'));

test/integration/fixtures/config/mocharcWithInvalidImport.js

@@ -0,0 +1,10 @@
+'use strict';
+
+require('invalidImport.js');
+// a comment
+module.exports = {
+  require: ['foo', 'bar'],
+  bail: true,
+  reporter: 'dot',
+  slow: 60
+};

test/integration/fixtures/config/mocharcWithThrowError.js

@@ -1,6 +1,6 @@
 'use strict';
 
-throw new Error("Error from mocharcWithThrowError");
+throw new Error('Error from mocharcWithThrowError');
 
 // a comment
 module.exports = {