ability to create error instances without new keyword

Author: dfenster

lib/helpers/class-generator.js

@@ -26,9 +26,17 @@ module.exports = function generateErrorClass(name, options){
     Class.captureStackTrace(this, Class);
   };
 
-  var classGeneratorFn = new Function('classConstructor',
-    "return function " + name + "(" + options.args.join(', ') + "){ classConstructor.apply(this, arguments); };"
-  );
+  var classGeneratorFn = new Function('classConstructor', [
+    "return function ", name, "(", options.args.join(', '), "){",
+      "if(!(this instanceof ", name, ")) {",
+        "var instance = Object.create(", name, ".prototype);",
+        "classConstructor.apply(instance, arguments);",
+        "return instance;",
+      "} else {",
+        "classConstructor.apply(this, arguments);",
+      "}",
+    "};",
+  ].join(''));
   var Class = classGeneratorFn(classConstructor);
 
   util.inherits(Class, options.extends);

lib/http-status.js

@@ -3,6 +3,12 @@ var util = require('util');
 var STATUS_CODE_ATTRIBUTE_NAME = module.exports.STATUS_CODE_ATTRIBUTE_NAME = 'status';
 
 var HttpStatusError = module.exports = function HttpStatusError(status_code, message) {
+  if(!(this instanceof HttpStatusError)) {
+    var instance = Object.create(HttpStatusError.prototype);
+    HttpStatusError.apply(instance, arguments);
+    return instance;
+  }
+
   if(typeof message == 'number' && typeof status_code != 'number') {
     //old interface, so swap.
     var c = message;

tests/http-status.js

@@ -0,0 +1,49 @@
+var assert = require('assert');
+var HttpStatusError = require('../').HttpStatusError;
+
+describe("HttpStatusError", function(){
+  function performBasicAssertions(error){
+    assert.equal(error.name, "HttpStatusError"), 'Its name is correct.';
+    console.log(error, error.stack)
+    assert.ok(new RegExp(error.name + ": " + error.message.replace(/\)/g, '\\)').replace(/\(/g, '\\(') + "\n(.*\n)+").test(error.stack), "Stack is good");
+    assert.ok(error instanceof Error, Error, "It is an instanceof Error");
+  }
+
+  it("should work with status code and message", function(){
+    var error = new HttpStatusError(403, "You got a 403");
+    assert.equal(error.message, "You got a 403");
+    assert.equal(error.status, 403);
+    assert.equal(error.status_code, 403);
+    assert.equal(error.statusCode, 403);
+    performBasicAssertions(error);
+  });
+
+  it("should work with status code", function(){
+    var error = new HttpStatusError(403);
+    assert.equal(error.message, "(403) Forbidden!");
+    assert.equal(error.status, 403);
+    assert.equal(error.status_code, 403);
+    assert.equal(error.statusCode, 403);
+    performBasicAssertions(error);
+  });
+
+  it("should work with status code and message without new", function(){
+    var error = HttpStatusError(403, "You got a 403");
+    assert.equal(error.message, "You got a 403");
+    assert.equal(error.status, 403);
+    assert.equal(error.status_code, 403);
+    assert.equal(error.statusCode, 403);
+    performBasicAssertions(error);
+  });
+
+  it("should work with status code without new", function(){
+    var error = HttpStatusError(403);
+    assert.equal(error.message, "(403) Forbidden!");
+    assert.equal(error.status, 403);
+    assert.equal(error.status_code, 403);
+    assert.equal(error.statusCode, 403);
+    performBasicAssertions(error);
+  });
+
+
+});

tests/support/index.js

@@ -8,18 +8,32 @@ module.exports.testError = function testError(name, opts){
   opts.extends = opts.extends || Error;
   opts.full_name = opts.full_name || name;
 
+  function performAssertions(Err, error) {
+    assert.equal(error.name, name), 'Its name is correct.';
+    assert.equal(error.message, opts.message_to_assert);
+    assert.ok(new RegExp(error.name + ": " + error.message + "\n(.*\n)+").test(error.stack), "Stack is good");
+    assert.equal(Err.super_.name, opts.extends.name, "It is an instance of" + opts.extends.name);
+    assert.ok(error instanceof Error, opts.extends, "It is an instanceof " + opts.extends.name);  
+  }  
+
   describe(name, function(){
+    var Err = errors;
+    (opts.full_name).split('.').forEach(function(dir){ Err = Err[dir]; });
+
     it("should work", function(){
-      var Err = errors;
-      (opts.full_name).split('.').forEach(function(dir){ Err = Err[dir]; });
       assert.ok(Err, name + " exists.");
       var inner_error = new Error("inner error");
       var error = new Err(opts.message);
-      assert.equal(error.name, name), 'Its name is correct.';
-      assert.equal(error.message, opts.message_to_assert);
-      assert.ok(new RegExp(error.name + ": " + error.message + "\n(.*\n)+").test(error.stack), "Stack is good");
-      assert.equal(Err.super_.name, opts.extends.name, "It is an instance of" + opts.extends.name);
-      assert.ok(error instanceof Error, opts.extends, "It is an instanceof " + opts.extends.name);
+
+      performAssertions(Err, error);
+    });
+
+    it("should work without new", function(){
+      assert.ok(Err, name + " exists.");
+      var inner_error = new Error("inner error");
+      var error = Err(opts.message);
+
+      performAssertions(Err, error);
     });
   });
 }