diff --git a/package.json b/package.json
index bc3afec921..d763fceaab 100644
--- a/package.json
+++ b/package.json
@@ -29,6 +29,7 @@
   },
   "homepage": "https://github.com/dolanmiu/docx#readme",
   "devDependencies": {
+    "chai": "^3.5.0",
     "mocha": "^2.4.5"
   }
 }
diff --git a/ts/tests/docxTest.ts b/ts/tests/docxTest.ts
index db5aa28153..f62a408e26 100644
--- a/ts/tests/docxTest.ts
+++ b/ts/tests/docxTest.ts
@@ -1,8 +1,10 @@
 /// <reference path="../typings/mocha/mocha.d.ts" />
+/// <reference path="../typings/chai/chai.d.ts" />
 import * as docx from "../docx";
+import {assert, } from "chai";
 
 describe('Calculator', () => {
-    var document : docx.Document;
+    var document: docx.Document;
 
     /*beforeEach(function () {
         subject = new Calculator();
@@ -23,5 +25,17 @@ describe('Calculator', () => {
         console.log(paragraph);
         console.log(JSON.stringify(paragraph, null, "    "));
         console.log(document.test());
+
+        it("should create valid JSON", () => {
+            var stringifiedJson = JSON.stringify(document);
+            var newJson;
+
+            try {
+                newJson = JSON.parse(stringifiedJson);
+            } catch (e) {
+                assert.isTrue(false);
+            }
+            assert.isTrue(true);
+        });
     });
 });
\ No newline at end of file
diff --git a/ts/tsd.json b/ts/tsd.json
index 2f0a03a834..814460eeaa 100644
--- a/ts/tsd.json
+++ b/ts/tsd.json
@@ -10,6 +10,12 @@
     },
     "lodash/lodash.d.ts": {
       "commit": "299b5caa22876ef27dc8e9a5b7fd7bf93457b6f4"
+    },
+    "chai/chai.d.ts": {
+      "commit": "80057d687aefa736511e434cd2a6c0e9a6bb02bc"
+    },
+    "assertion-error/assertion-error.d.ts": {
+      "commit": "80057d687aefa736511e434cd2a6c0e9a6bb02bc"
     }
   }
 }
diff --git a/ts/typings/assertion-error/assertion-error.d.ts b/ts/typings/assertion-error/assertion-error.d.ts
new file mode 100644
index 0000000000..a0295bd8b3
--- /dev/null
+++ b/ts/typings/assertion-error/assertion-error.d.ts
@@ -0,0 +1,15 @@
+// Type definitions for assertion-error 1.0.0
+// Project: https://github.com/chaijs/assertion-error
+// Definitions by: Bart van der Schoor <https://github.com/Bartvds>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+declare module 'assertion-error' {
+	class AssertionError implements Error {
+		constructor(message: string, props?: any, ssf?: Function);
+		name: string;
+		message: string;
+		showDiff: boolean;
+		stack: string;
+	}
+	export = AssertionError;
+}
diff --git a/ts/typings/chai/chai.d.ts b/ts/typings/chai/chai.d.ts
new file mode 100644
index 0000000000..0ebc855022
--- /dev/null
+++ b/ts/typings/chai/chai.d.ts
@@ -0,0 +1,401 @@
+// Type definitions for chai 3.4.0
+// Project: http://chaijs.com/
+// Definitions by: Jed Mao <https://github.com/jedmao/>,
+//                 Bart van der Schoor <https://github.com/Bartvds>,
+//                 Andrew Brown <https://github.com/AGBrown>,
+//                 Olivier Chevet <https://github.com/olivr70>,
+//                 Matt Wistrand <https://github.com/mwistrand>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+// <reference path="../assertion-error/assertion-error.d.ts"/>
+
+declare namespace Chai {
+
+    interface ChaiStatic {
+        expect: ExpectStatic;
+        should(): Should;
+        /**
+         * Provides a way to extend the internals of Chai
+         */
+        use(fn: (chai: any, utils: any) => void): ChaiStatic;
+        assert: AssertStatic;
+        config: Config;
+        AssertionError: typeof AssertionError;
+    }
+
+    export interface ExpectStatic extends AssertionStatic {
+        fail(actual?: any, expected?: any, message?: string, operator?: string): void;
+    }
+
+    export interface AssertStatic extends Assert {
+    }
+
+    export interface AssertionStatic {
+        (target: any, message?: string): Assertion;
+    }
+
+    interface ShouldAssertion {
+        equal(value1: any, value2: any, message?: string): void;
+        Throw: ShouldThrow;
+        throw: ShouldThrow;
+        exist(value: any, message?: string): void;
+    }
+
+    interface Should extends ShouldAssertion {
+        not: ShouldAssertion;
+        fail(actual: any, expected: any, message?: string, operator?: string): void;
+    }
+
+    interface ShouldThrow {
+        (actual: Function): void;
+        (actual: Function, expected: string|RegExp, message?: string): void;
+        (actual: Function, constructor: Error|Function, expected?: string|RegExp, message?: string): void;
+    }
+
+    interface Assertion extends LanguageChains, NumericComparison, TypeComparison {
+        not: Assertion;
+        deep: Deep;
+        any: KeyFilter;
+        all: KeyFilter;
+        a: TypeComparison;
+        an: TypeComparison;
+        include: Include;
+        includes: Include;
+        contain: Include;
+        contains: Include;
+        ok: Assertion;
+        true: Assertion;
+        false: Assertion;
+        null: Assertion;
+        undefined: Assertion;
+        NaN: Assertion;
+        exist: Assertion;
+        empty: Assertion;
+        arguments: Assertion;
+        Arguments: Assertion;
+        equal: Equal;
+        equals: Equal;
+        eq: Equal;
+        eql: Equal;
+        eqls: Equal;
+        property: Property;
+        ownProperty: OwnProperty;
+        haveOwnProperty: OwnProperty;
+        ownPropertyDescriptor: OwnPropertyDescriptor;
+        haveOwnPropertyDescriptor: OwnPropertyDescriptor;
+        length: Length;
+        lengthOf: Length;
+        match: Match;
+        matches: Match;
+        string(string: string, message?: string): Assertion;
+        keys: Keys;
+        key(string: string): Assertion;
+        throw: Throw;
+        throws: Throw;
+        Throw: Throw;
+        respondTo: RespondTo;
+        respondsTo: RespondTo;
+        itself: Assertion;
+        satisfy: Satisfy;
+        satisfies: Satisfy;
+        closeTo: CloseTo;
+        approximately: CloseTo;
+        members: Members;
+        increase: PropertyChange;
+        increases: PropertyChange;
+        decrease: PropertyChange;
+        decreases: PropertyChange;
+        change: PropertyChange;
+        changes: PropertyChange;
+        extensible: Assertion;
+        sealed: Assertion;
+        frozen: Assertion;
+        oneOf(list: any[], message?: string): Assertion;
+    }
+
+    interface LanguageChains {
+        to: Assertion;
+        be: Assertion;
+        been: Assertion;
+        is: Assertion;
+        that: Assertion;
+        which: Assertion;
+        and: Assertion;
+        has: Assertion;
+        have: Assertion;
+        with: Assertion;
+        at: Assertion;
+        of: Assertion;
+        same: Assertion;
+    }
+
+    interface NumericComparison {
+        above: NumberComparer;
+        gt: NumberComparer;
+        greaterThan: NumberComparer;
+        least: NumberComparer;
+        gte: NumberComparer;
+        below: NumberComparer;
+        lt: NumberComparer;
+        lessThan: NumberComparer;
+        most: NumberComparer;
+        lte: NumberComparer;
+        within(start: number, finish: number, message?: string): Assertion;
+    }
+
+    interface NumberComparer {
+        (value: number, message?: string): Assertion;
+    }
+
+    interface TypeComparison {
+        (type: string, message?: string): Assertion;
+        instanceof: InstanceOf;
+        instanceOf: InstanceOf;
+    }
+
+    interface InstanceOf {
+        (constructor: Object, message?: string): Assertion;
+    }
+
+    interface CloseTo {
+        (expected: number, delta: number, message?: string): Assertion;
+    }
+
+    interface Deep {
+        equal: Equal;
+        include: Include;
+        property: Property;
+        members: Members;
+    }
+
+    interface KeyFilter {
+        keys: Keys;
+    }
+
+    interface Equal {
+        (value: any, message?: string): Assertion;
+    }
+
+    interface Property {
+        (name: string, value?: any, message?: string): Assertion;
+    }
+
+    interface OwnProperty {
+        (name: string, message?: string): Assertion;
+    }
+
+    interface OwnPropertyDescriptor {
+        (name: string, descriptor: PropertyDescriptor, message?: string): Assertion;
+        (name: string, message?: string): Assertion;
+    }
+
+    interface Length extends LanguageChains, NumericComparison {
+        (length: number, message?: string): Assertion;
+    }
+
+    interface Include {
+        (value: Object, message?: string): Assertion;
+        (value: string, message?: string): Assertion;
+        (value: number, message?: string): Assertion;
+        keys: Keys;
+        members: Members;
+        any: KeyFilter;
+        all: KeyFilter;
+    }
+
+    interface Match {
+        (regexp: RegExp|string, message?: string): Assertion;
+    }
+
+    interface Keys {
+        (...keys: string[]): Assertion;
+        (keys: any[]): Assertion;
+        (keys: Object): Assertion;
+    }
+
+    interface Throw {
+        (): Assertion;
+        (expected: string, message?: string): Assertion;
+        (expected: RegExp, message?: string): Assertion;
+        (constructor: Error, expected?: string, message?: string): Assertion;
+        (constructor: Error, expected?: RegExp, message?: string): Assertion;
+        (constructor: Function, expected?: string, message?: string): Assertion;
+        (constructor: Function, expected?: RegExp, message?: string): Assertion;
+    }
+
+    interface RespondTo {
+        (method: string, message?: string): Assertion;
+    }
+
+    interface Satisfy {
+        (matcher: Function, message?: string): Assertion;
+    }
+
+    interface Members {
+        (set: any[], message?: string): Assertion;
+    }
+
+    interface PropertyChange {
+        (object: Object, prop: string, msg?: string): Assertion;
+    }
+
+    export interface Assert {
+        /**
+         * @param expression Expression to test for truthiness.
+         * @param message Message to display on error.
+         */
+        (expression: any, message?: string): void;
+
+        fail(actual?: any, expected?: any, msg?: string, operator?: string): void;
+
+        ok(val: any, msg?: string): void;
+        isOk(val: any, msg?: string): void;
+        notOk(val: any, msg?: string): void;
+        isNotOk(val: any, msg?: string): void;
+
+        equal(act: any, exp: any, msg?: string): void;
+        notEqual(act: any, exp: any, msg?: string): void;
+
+        strictEqual(act: any, exp: any, msg?: string): void;
+        notStrictEqual(act: any, exp: any, msg?: string): void;
+
+        deepEqual(act: any, exp: any, msg?: string): void;
+        notDeepEqual(act: any, exp: any, msg?: string): void;
+
+        isTrue(val: any, msg?: string): void;
+        isFalse(val: any, msg?: string): void;
+
+        isNotTrue(val: any, msg?: string): void;
+        isNotFalse(val: any, msg?: string): void;
+
+        isNull(val: any, msg?: string): void;
+        isNotNull(val: any, msg?: string): void;
+
+        isUndefined(val: any, msg?: string): void;
+        isDefined(val: any, msg?: string): void;
+
+        isNaN(val: any, msg?: string): void;
+        isNotNaN(val: any, msg?: string): void;
+
+        isAbove(val: number, abv: number, msg?: string): void;
+        isBelow(val: number, blw: number, msg?: string): void;
+
+        isAtLeast(val: number, atlst: number, msg?: string): void;
+        isAtMost(val: number, atmst: number, msg?: string): void;
+
+        isFunction(val: any, msg?: string): void;
+        isNotFunction(val: any, msg?: string): void;
+
+        isObject(val: any, msg?: string): void;
+        isNotObject(val: any, msg?: string): void;
+
+        isArray(val: any, msg?: string): void;
+        isNotArray(val: any, msg?: string): void;
+
+        isString(val: any, msg?: string): void;
+        isNotString(val: any, msg?: string): void;
+
+        isNumber(val: any, msg?: string): void;
+        isNotNumber(val: any, msg?: string): void;
+
+        isBoolean(val: any, msg?: string): void;
+        isNotBoolean(val: any, msg?: string): void;
+
+        typeOf(val: any, type: string, msg?: string): void;
+        notTypeOf(val: any, type: string, msg?: string): void;
+
+        instanceOf(val: any, type: Function, msg?: string): void;
+        notInstanceOf(val: any, type: Function, msg?: string): void;
+
+        include(exp: string, inc: any, msg?: string): void;
+        include(exp: any[], inc: any, msg?: string): void;
+
+        notInclude(exp: string, inc: any, msg?: string): void;
+        notInclude(exp: any[], inc: any, msg?: string): void;
+
+        match(exp: any, re: RegExp, msg?: string): void;
+        notMatch(exp: any, re: RegExp, msg?: string): void;
+
+        property(obj: Object, prop: string, msg?: string): void;
+        notProperty(obj: Object, prop: string, msg?: string): void;
+        deepProperty(obj: Object, prop: string, msg?: string): void;
+        notDeepProperty(obj: Object, prop: string, msg?: string): void;
+
+        propertyVal(obj: Object, prop: string, val: any, msg?: string): void;
+        propertyNotVal(obj: Object, prop: string, val: any, msg?: string): void;
+
+        deepPropertyVal(obj: Object, prop: string, val: any, msg?: string): void;
+        deepPropertyNotVal(obj: Object, prop: string, val: any, msg?: string): void;
+
+        lengthOf(exp: any, len: number, msg?: string): void;
+        //alias frenzy
+        throw(fn: Function, msg?: string): void;
+        throw(fn: Function, regExp: RegExp): void;
+        throw(fn: Function, errType: Function, msg?: string): void;
+        throw(fn: Function, errType: Function, regExp: RegExp): void;
+
+        throws(fn: Function, msg?: string): void;
+        throws(fn: Function, regExp: RegExp): void;
+        throws(fn: Function, errType: Function, msg?: string): void;
+        throws(fn: Function, errType: Function, regExp: RegExp): void;
+
+        Throw(fn: Function, msg?: string): void;
+        Throw(fn: Function, regExp: RegExp): void;
+        Throw(fn: Function, errType: Function, msg?: string): void;
+        Throw(fn: Function, errType: Function, regExp: RegExp): void;
+
+        doesNotThrow(fn: Function, msg?: string): void;
+        doesNotThrow(fn: Function, regExp: RegExp): void;
+        doesNotThrow(fn: Function, errType: Function, msg?: string): void;
+        doesNotThrow(fn: Function, errType: Function, regExp: RegExp): void;
+
+        operator(val: any, operator: string, val2: any, msg?: string): void;
+        closeTo(act: number, exp: number, delta: number, msg?: string): void;
+        approximately(act: number, exp: number, delta: number, msg?: string): void;
+
+        sameMembers(set1: any[], set2: any[], msg?: string): void;
+        sameDeepMembers(set1: any[], set2: any[], msg?: string): void;
+        includeMembers(superset: any[], subset: any[], msg?: string): void;
+
+        ifError(val: any, msg?: string): void;
+
+        isExtensible(obj: {}, msg?: string): void;
+        extensible(obj: {}, msg?: string): void;
+        isNotExtensible(obj: {}, msg?: string): void;
+        notExtensible(obj: {}, msg?: string): void;
+
+        isSealed(obj: {}, msg?: string): void;
+        sealed(obj: {}, msg?: string): void;
+        isNotSealed(obj: {}, msg?: string): void;
+        notSealed(obj: {}, msg?: string): void;
+
+        isFrozen(obj: Object, msg?: string): void;
+        frozen(obj: Object, msg?: string): void;
+        isNotFrozen(obj: Object, msg?: string): void;
+        notFrozen(obj: Object, msg?: string): void;
+
+        oneOf(inList: any, list: any[], msg?: string): void;
+    }
+
+    export interface Config {
+        includeStack: boolean;
+    }
+
+    export class AssertionError {
+        constructor(message: string, _props?: any, ssf?: Function);
+        name: string;
+        message: string;
+        showDiff: boolean;
+        stack: string;
+    }
+}
+
+declare var chai: Chai.ChaiStatic;
+
+declare module "chai" {
+    export = chai;
+}
+
+interface Object {
+    should: Chai.Assertion;
+}
diff --git a/ts/typings/tsd.d.ts b/ts/typings/tsd.d.ts
index b1f3f40e90..c8d432b36c 100644
--- a/ts/typings/tsd.d.ts
+++ b/ts/typings/tsd.d.ts
@@ -1,3 +1,5 @@
 
 /// <reference path="mocha/mocha.d.ts" />
 /// <reference path="lodash/lodash.d.ts" />
+/// <reference path="assertion-error/assertion-error.d.ts" />
+/// <reference path="chai/chai.d.ts" />