fix: fix new Function and add test case

src/evaluate.ts

@@ -293,6 +293,7 @@ const visitors: EvaluateMap = {
       scope.$var(functionName, generatorFunc);
     } else {
       const func = visitors.FunctionExpression(path.$child(node as any));
+
       Object.defineProperties(func, {
         length: { value: node.params.length },
         name: { value: functionName }
@@ -906,9 +907,11 @@ const visitors: EvaluateMap = {
   NewExpression(path) {
     const { node } = path;
     const func = evaluate(path.$child(node.callee));
-    Object.defineProperty(func, "length", { value: node.arguments.length });
-    const args = node.arguments.map(arg => evaluate(path.$child(arg)));
-    return new (func.bind.apply(func, [null].concat(args)))();
+    const args: any[] = node.arguments.map(arg => evaluate(path.$child(arg)));
+    const entity = new func(...args);
+    entity.prototype = entity.prototype || {};
+    entity.prototype.constructor = func;
+    return entity;
   },
 
   // ES2015

test/ecma5/new/NewExpression.test.ts

@@ -4,18 +4,26 @@ import vm from "../../../src/vm";
 test("NewExpression", t => {
   const sandbox: any = vm.createContext({});
 
-  const output: any = vm.runInContext(
+  const { people, People }: any = vm.runInContext(
     `
-function People(name){
+function People(name, age){
   this.name = name;
 }
 
-module.exports = new People("axetroy");
-module.exports.People = People;
+module.exports = {
+  people: new People("axetroy", 12),
+  People: People
+};
   `,
     sandbox
   );
 
-  t.deepEqual(output.People.length, 1);
-  t.deepEqual(output.name, "axetroy");
+  // constructor
+  t.deepEqual(People.length, 2);
+  t.deepEqual(People.name, "People");
+
+  // entity
+  t.true(people instanceof People);
+  t.deepEqual(people.name, "axetroy");
+  t.true(people.prototype.constructor === People);
 });