WIP: module,errors: port module to internal/errors

doc/api/errors.md

@@ -255,6 +255,13 @@ will affect any stack trace captured *after* the value has been changed.
 If set to a non-number value, or set to a negative number, stack traces will
 not capture any frames.
 
+#### error.code
+
+* {string}
+
+The `error.code` property is a string label that identifies the kind of error.
+See [Node.js Error Codes][] for details about specific codes.
+
 ### error.message
 
 * {string}
@@ -550,6 +557,15 @@ found [here][online].
   encountered by [`http`][] or [`net`][] -- often a sign that a `socket.end()`
   was not properly called.
 
+<a id="nodejs-error-codes"></a>
+## Node.js Error Codes
+
+<a id="MODULE_NOT_FOUND"></a>
+### MODULE_NOT_FOUND
+
+The `'MODULE_NOT_FOUND'` error is thrown if `require()` is called on
+file that does not exist.
+
 [`fs.readdir`]: fs.html#fs_fs_readdir_path_options_callback
 [`fs.readFileSync`]: fs.html#fs_fs_readfilesync_file_options
 [`fs.unlink`]: fs.html#fs_fs_unlink_path_callback
@@ -562,6 +578,7 @@ found [here][online].
 [domains]: domain.html
 [event emitter-based]: events.html#events_class_eventemitter
 [file descriptors]: https://en.wikipedia.org/wiki/File_descriptor
+[Node.js Error Codes]: #nodejs-error-codes
 [online]: http://man7.org/linux/man-pages/man3/errno.3.html
 [stream-based]: stream.html
 [syscall]: http://man7.org/linux/man-pages/man2/syscall.2.html

lib/internal/errors.js

@@ -88,3 +88,7 @@ module.exports = exports = {
 // Note: Please try to keep these in alphabetical order
 E('ERR_ASSERTION', (msg) => msg);
 // Add new errors from here...
+E('MODULE_NOT_FOUND', (request) => `Cannot find module '${request}'`);
+E('ERR_PARSING_JSON', (filePath, message) => (
+  `Error parsing '${filePath}': ${message}`
+));

lib/module.js

@@ -23,6 +23,7 @@
 
 const NativeModule = require('native_module');
 const util = require('util');
+const errors = require('internal/errors');
 const internalModule = require('internal/module');
 const vm = require('vm');
 const assert = require('assert').ok;
@@ -482,8 +483,7 @@ Module._resolveFilename = function(request, parent, isMain) {
   // look up the filename first, since that's the cache key.
   var filename = Module._findPath(request, paths, isMain);
   if (!filename) {
-    var err = new Error(`Cannot find module '${request}'`);
-    err.code = 'MODULE_NOT_FOUND';
+    const err = new errors.Error('MODULE_NOT_FOUND', request);
     throw err;
   }
   return filename;

test/parallel/test-cli-syntax.js

@@ -4,6 +4,7 @@ const common = require('../common');
 const assert = require('assert');
 const spawnSync = require('child_process').spawnSync;
 const path = require('path');
+const errors = require('../../lib/internal/errors');
 
 const node = process.execPath;
 
@@ -76,7 +77,8 @@ const syntaxArgs = [
     assert.strictEqual(c.stdout, '', 'stdout produced');
 
     // stderr should have a module not found error message
-    const match = c.stderr.match(/^Error: Cannot find module/m);
+    const expectedError = new errors.Error('MODULE_NOT_FOUND', file);
+    const match = c.stderr.match(expectedError.message);
     assert(match, 'stderr incorrect');
 
     assert.strictEqual(c.status, 1, 'code == ' + c.status);

test/parallel/test-internal-modules.js

@@ -2,10 +2,13 @@
 const common = require('../common');
 const path = require('path');
 const assert = require('assert');
+const errors = require('../../lib/internal/errors');
 
+const internalModuleName = 'internal/freelist';
+const expectedError = new errors.Error('MODULE_NOT_FOUND', internalModuleName);
 assert.throws(function() {
-  require('internal/freelist');
-}, /^Error: Cannot find module 'internal\/freelist'$/);
+  require(internalModuleName);
+}, new RegExp(expectedError.message));
 
 assert.strictEqual(
   require(path.join(common.fixturesDir, 'internal-modules')),

test/parallel/test-repl.js

@@ -23,6 +23,7 @@
 'use strict';
 const common = require('../common');
 const assert = require('assert');
+const errors = require('../../lib/internal/errors');
 
 common.globalCheck = false;
 common.refreshTmpDir();
@@ -343,8 +344,10 @@ function error_test() {
       expect: 'undefined\n' + prompt_unix },
     // REPL should get a normal require() function, not one that allows
     // access to internal modules without the --expose_internals flag.
-    { client: client_unix, send: 'require("internal/repl")',
-      expect: /^Error: Cannot find module 'internal\/repl'/ },
+    {
+      client: client_unix, send: 'require("internal/repl")',
+      expect: new RegExp(new errors.Error('MODULE_NOT_FOUND', 'internal/repl').message)
+    },
     // REPL should handle quotes within regexp literal in multiline mode
     { client: client_unix,
       send: "function x(s) {\nreturn s.replace(/'/,'');\n}",

test/sequential/test-module-loading.js

@@ -24,6 +24,7 @@ require('../common');
 const assert = require('assert');
 const path = require('path');
 const fs = require('fs');
+const errors = require('../../lib/internal/errors');
 
 console.error('load test-module-loading.js');
 
@@ -120,8 +121,10 @@ console.error('test name clashes');
 const my_path = require('../fixtures/path');
 assert.ok(my_path.path_func instanceof Function);
 // this one does not exist and should throw
-assert.throws(function() { require('./utils'); },
-              /^Error: Cannot find module '.\/utils'$/);
+const notFoundPath = './utils';
+const notFoundError = new errors.Error('MODULE_NOT_FOUND', notFoundPath);
+assert.throws(function() { require(notFoundPath); },
+              new RegExp(notFoundError.message));
 
 let errorThrown = false;
 try {
@@ -224,6 +227,7 @@ const children = module.children.reduce(function red(set, child) {
 
 assert.deepStrictEqual(children, {
   'common.js': {},
+  '../lib/internal/errors.js': {},
   'fixtures/not-main-module.js': {},
   'fixtures/a.js': {
     'fixtures/b/c.js': {