diff --git a/package.json b/package.json
index 3389901..096cb66 100644
--- a/package.json
+++ b/package.json
@@ -97,4 +97,4 @@
     "validate-commit-msg": "^2.14.0",
     "webpack-config-utils": "^2.3.0"
   }
-}
+}
\ No newline at end of file
diff --git a/src/core/type.ts b/src/core/type.ts
index 778a1a3..c80ecad 100644
--- a/src/core/type.ts
+++ b/src/core/type.ts
@@ -5,7 +5,7 @@ export interface Type<T> extends Function {
 }
 
 export declare type IdentityType<T> = T | symbol;
-export declare type PropertyKeyType = IdentityType<string | number>;
+export declare type PropertyKeyType = IdentityType<string>;
 export declare type MetadataKeyType = IdentityType<string>;
 
 export enum PrimitiveType {
diff --git a/src/reflect/AccessibleObject.ts b/src/reflect/AccessibleObject.ts
index 2150163..151b3bb 100644
--- a/src/reflect/AccessibleObject.ts
+++ b/src/reflect/AccessibleObject.ts
@@ -21,7 +21,7 @@ export abstract class AccessibleObject implements AnnotatedElement {
   }
 
   public isAnnotationPresent<AnnotationType extends Annotation>(annotationClass: Type<AnnotationType>): boolean {
-    return null !== this.getAnnotation(annotationClass);
+    return undefined !== this.getAnnotation(annotationClass);
   }
 
   public getOwnAnnotation<AnnotationType extends Annotation>(annotationClass: Type<AnnotationType>): AnnotationType | undefined {
diff --git a/src/reflect/Class.ts b/src/reflect/Class.ts
index 29180d3..00175db 100644
--- a/src/reflect/Class.ts
+++ b/src/reflect/Class.ts
@@ -38,11 +38,9 @@ export class Class extends AccessibleObject {
       SystemClassRegistry.set(type, clazz);
     }
 
-    if (null === clazz._constructor) {
+    if (undefined === clazz._constructor) {
       const parameterTypes = Metadata.getOwnParamTypes(type);
-      if (undefined !== parameterTypes) {
-        clazz._constructor = new Constructor(clazz, parameterTypes);
-      }
+      clazz._constructor = new Constructor(clazz, parameterTypes);
     }
 
     return clazz;
@@ -124,9 +122,6 @@ export class Class extends AccessibleObject {
     const fields: Map<PropertyKeyType, Field> = new Map();
 
     const types = TypeUtil.ancestorsOf(this._type);
-    if (null === types || 0 === types.length) {
-      return fields;
-    }
     for (let i = 0; i < types.length; i++) {
       const tType = types[i];
       const tClazz = Class.forType(tType);
@@ -160,9 +155,6 @@ export class Class extends AccessibleObject {
     const methods: Map<PropertyKeyType, Method> = new Map();
 
     const types = TypeUtil.ancestorsOf(this._type);
-    if (null === types || 0 === types.length) {
-      return methods;
-    }
     for (let i = 0; i < types.length; i++) {
       const tClazzType = types[i];
       const tClazz = Class.forType(tClazzType);
@@ -188,9 +180,6 @@ export class Class extends AccessibleObject {
     const annotations: Map<Type<any>, Annotation> = new Map();
 
     const types = TypeUtil.ancestorsOf(this._type);
-    if (null === types || 0 === types.length) {
-      return annotations;
-    }
     for (let i = 0; i < types.length; i++) {
       const tClazzType = types[i];
       const tClazz = Class.forType(tClazzType);
diff --git a/src/reflect/Constructor.ts b/src/reflect/Constructor.ts
index 50dc52b..f0f669e 100644
--- a/src/reflect/Constructor.ts
+++ b/src/reflect/Constructor.ts
@@ -5,6 +5,8 @@
 import { Class } from './Class';
 import { Executable } from './Executable';
 
+const CONSTRUCTOR_NAME = 'constructor';
+
 export class Constructor extends Executable {
   // private _rawConstructor: Function;
 
@@ -19,5 +21,3 @@ export class Constructor extends Executable {
     return new (ctor.bind.apply(ctor, [null].concat(args)))();
   }
 }
-
-const CONSTRUCTOR_NAME = 'constructor';
diff --git a/src/reflect/Executable.ts b/src/reflect/Executable.ts
index c6ef735..0199642 100644
--- a/src/reflect/Executable.ts
+++ b/src/reflect/Executable.ts
@@ -49,10 +49,6 @@ export abstract class Executable extends AccessibleObject implements Member {
    * getParameterCount
    */
   public getParameterCount(): number {
-    if (null === this._parameters) {
-      return 0;
-    }
-
     return this._parameters.length;
   }
   /**
@@ -65,9 +61,6 @@ export abstract class Executable extends AccessibleObject implements Member {
    * getParameter
    */
   public getParameter(index: number): Parameter | undefined {
-    if (null === this._parameters) {
-      return undefined;
-    }
     if (0 > index || this._parameters.length <= index) {
       return undefined;
     }
diff --git a/src/reflect/Metadata.ts b/src/reflect/Metadata.ts
index 881df21..055ccf5 100644
--- a/src/reflect/Metadata.ts
+++ b/src/reflect/Metadata.ts
@@ -5,6 +5,31 @@ import {
 
 import { TypeUtil } from '../util/TypeUtil';
 
+/**
+ * Metadata key
+ * @private
+ * @type {string}
+ */
+const DESIGN_PARAM_TYPES = 'design:paramtypes';
+/**
+ * Metadata key
+ * @private
+ * @type {string}
+ */
+const DESIGN_TYPE = 'design:type';
+/**
+ * Metadata key
+ * @private
+ * @type {string}
+ */
+const DESIGN_RETURN_TYPE = 'design:returntype';
+/**
+ * Properties collections
+ * @private
+ * @type {string}
+ */
+const PROPERTIES: Map<MetadataKeyType, any[]> = new Map<MetadataKeyType, any[]>();
+
 export class Metadata {
   /**
    * Gets the metadata value for the provided metadata key on the target object or its prototype chain.
@@ -504,28 +529,3 @@ export class Metadata {
     return Reflect.getOwnMetadata(DESIGN_PARAM_TYPES, target, propertyKey);
   }
 }
-
-/**
- * Metadata key
- * @private
- * @type {string}
- */
-const DESIGN_PARAM_TYPES = 'design:paramtypes';
-/**
- * Metadata key
- * @private
- * @type {string}
- */
-const DESIGN_TYPE = 'design:type';
-/**
- * Metadata key
- * @private
- * @type {string}
- */
-const DESIGN_RETURN_TYPE = 'design:returntype';
-/**
- * Properties collections
- * @private
- * @type {string}
- */
-const PROPERTIES: Map<MetadataKeyType, any[]> = new Map<MetadataKeyType, any[]>();
diff --git a/src/util/TypeUtil.ts b/src/util/TypeUtil.ts
index a1467b2..4a7b761 100644
--- a/src/util/TypeUtil.ts
+++ b/src/util/TypeUtil.ts
@@ -4,6 +4,10 @@ import {
   Type,
 } from '../core';
 
+const COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;
+const DEFAULT_PARAMS = /=[^,]+/mg;
+const FAT_ARROWS = /=>.*$/mg;
+
 export class TypeUtil {
   /**
    * Get the provide constructor.
@@ -151,7 +155,7 @@ export class TypeUtil {
    * @returns {boolean}
    */
   public static isMethod(target: any, propertyKey: PropertyKeyType): boolean {
-    if (typeof(target[propertyKey]) === undefined) {
+    if (typeof target.propertyKey === 'undefined') {
       return false;
     }
 
@@ -389,26 +393,27 @@ export class TypeUtil {
    * @param {number} time
    * @returns {Promise<any>}
    */
-  public static promiseTimeout(promise: Promise<any>, time = 1000): Promise<{ ok: boolean, response: any }> {
-    const timeout = (p: Promise<any>, t: number) => new Promise((resolve) => {
-      p.then((response) => {
-        resolve();
-
-        return response;
-      });
-      setTimeout(() => resolve({ ok: false }), t);
-    });
-
-    promise = promise.then((response) => ({ ok: true, response }));
+  public static promiseTimeout(promise: Promise<any>, timeout = 1000): Promise<{ ok: boolean, response?: any }> {
+    let _hTimeout: any;
 
     return Promise.race([
       promise,
-      timeout(promise, time),
+      new Promise((resolve, reject) => {
+        promise.then(response => {
+          clearTimeout(_hTimeout);
+
+          resolve();
+
+          return { ok: true, response };
+        }).catch(reason => {
+          clearTimeout(_hTimeout);
+          reject(reason);
+        });
+
+        _hTimeout = setTimeout(() => {
+          resolve({ ok: false });
+        }, timeout);
+      }),
     ]);
   }
-
 }
-
-const COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;
-const DEFAULT_PARAMS = /=[^,]+/mg;
-const FAT_ARROWS = /=>.*$/mg;
diff --git a/src/util/index.ts b/src/util/index.ts
index d289752..fc67c99 100644
--- a/src/util/index.ts
+++ b/src/util/index.ts
@@ -1,3 +1,3 @@
 export * from './AnnotationUtil';
 export * from './Registry';
-export * from './TypeUtil';
\ No newline at end of file
+export * from './TypeUtil';
diff --git a/tsconfig.json b/tsconfig.json
index 78b0be7..a3a84db 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -4,6 +4,8 @@
     "module": "esnext",
     "target": "es5",
     "types": [
+      "jest",
+      "node",
       "reflect-metadata",
     ],
     "lib": [