diff --git a/expect/expect-tests.ts b/expect/expect-tests.ts
new file mode 100644
index 000000000..a0d2bf792
--- /dev/null
+++ b/expect/expect-tests.ts
@@ -0,0 +1,695 @@
+/// <reference path="./expect.d.ts" />
+/// <reference path="../mocha/mocha.d.ts"" />
+
+import expect,
+      {Expectation, Extension, Spy, createSpy, isSpy, assert, spyOn, extend, restoreSpies}
+      from 'expect';
+
+describe('chaining assertions', function () {
+  it('should allow chaining for array-like applications', function () {
+    expect([ 1, 2, 'foo', 3 ])
+      .toExist()
+      .toBeAn(Array)
+      .toInclude('foo')
+      .toExclude('bar')
+  })
+
+  it('should allow chaining for number checking', function () {
+    expect(3.14)
+      .toExist()
+      .toBeLessThan(4.2)
+      .toBeGreaterThan(3.0)
+  })
+})
+describe('createSpy', function () {
+  describe('when given a function', function () {
+    it('returns a spy function', function () {
+      const spy = createSpy(function () {})
+      expect(spy).toBeA(Function)
+    })
+  })
+})
+
+describe('A spy', function () {
+  let targetContext:any, targetArguments:any;
+  const target = {
+    method: function () {
+      targetContext = this
+      targetArguments = Array.prototype.slice.call(arguments, 0)
+    }
+  }
+
+  let spy:any;
+
+  it('is a spy', function () {
+    expect(isSpy(spy)).toBe(true)
+  })
+
+  it('has a destroy method', function () {
+    expect(spy.destroy).toBeA(Function)
+  })
+
+  it('has a restore method', function () {
+    expect(spy.restore).toBeA(Function)
+  })
+
+  it('knows how many times it has been called', function () {
+    spy()
+    spy()
+    expect(spy.calls.length).toEqual(2)
+  })
+
+  it('knows the arguments it was called with', function () {
+    spy(1, 2, 3)
+    expect(spy).toHaveBeenCalledWith(1, 2, 3)
+  })
+
+  describe('that calls some other function', function () {
+    let otherContext:any, otherArguments:any;
+    function otherFn() {
+      otherContext = this
+      otherArguments = Array.prototype.slice.call(arguments, 0)
+    }
+
+    beforeEach(function () {
+      spy.andCall(otherFn)
+      otherContext = otherArguments = null
+    })
+
+    it('calls that function', function () {
+      spy()
+      expect(otherContext).toNotBe(null)
+    })
+
+    it('uses the correct context', function () {
+      const context = {}
+      spy.call(context)
+      expect(otherContext).toBe(context)
+    })
+
+    it('passes the arguments through', function () {
+      spy(1, 2, 3)
+      expect(otherArguments).toEqual([ 1, 2, 3 ])
+    })
+  })
+
+  describe('that calls through', function () {
+    beforeEach(function () {
+      spy.andCallThrough()
+    })
+
+    it('calls the original function', function () {
+      spy()
+      expect(targetContext).toNotBe(null)
+    })
+
+    it('uses the correct context', function () {
+      const context = {}
+      spy.call(context)
+      expect(targetContext).toBe(context)
+    })
+
+    it('passes the arguments through', function () {
+      spy(1, 2, 3)
+      expect(targetArguments).toEqual([ 1, 2, 3 ])
+    })
+  })
+
+  describe('with a thrown value', function () {
+    beforeEach(function () {
+      spy.andThrow('hello')
+    })
+
+    it('throws the correct value', function () {
+      expect(spy).toThrow('hello')
+    })
+  })
+
+  describe('with a return value', function () {
+    beforeEach(function () {
+      spy.andReturn('hello')
+    })
+
+    it('returns the correct value', function () {
+      expect(spy()).toEqual('hello')
+    })
+  })
+})
+describe('expect.extend', function () {
+  const ColorAssertions:Extension = {
+    toBeAColor() {
+      assert(
+        this.actual.match(/^#[a-fA-F0-9]{6}$/),
+        'expected %s to be an HTML color',
+        this.actual
+      )
+    }
+  }
+
+  let assertSpy:Spy;
+  beforeEach(function () {
+    extend(ColorAssertions)
+    assertSpy = spyOn(expect, 'assert')
+  })
+
+  afterEach(function () {
+    assertSpy.restore()
+  })
+
+  it('works', function () {
+    interface ColorExpectation extends Expectation {
+      toBeAColor():Expectation;
+    }
+    (<ColorExpectation>expect('#ff00ff')).toBeAColor()
+    expect(assertSpy).toHaveBeenCalled()
+  })
+})
+
+describe('restoreSpies', function () {
+  describe('with one spy', function () {
+    const original = function () {}
+    const target = { method: original }
+
+    beforeEach(function () {
+      spyOn(target, 'method')
+    })
+
+    it('works with spyOn()', function () {
+      expect(target.method).toNotEqual(original)
+      restoreSpies()
+      expect(target.method).toEqual(original)
+    })
+
+    it('is idempotent', function () {
+      expect(target.method).toNotEqual(original)
+      restoreSpies()
+      restoreSpies()
+      expect(target.method).toEqual(original)
+    })
+
+    it('can work even on createSpy()', function () {
+      createSpy(original)
+      restoreSpies()
+    })
+  })
+
+  describe('with multiple spies', function () {
+    const originals = [ function () {}, function () {} ]
+    const targets = [
+      { method: originals[0] },
+      { method: originals[1] }
+    ]
+
+    it('still works', function () {
+      spyOn(targets[0], 'method')
+      spyOn(targets[1], 'method')
+
+      expect(targets[0].method).toNotEqual(originals[0])
+      expect(targets[1].method).toNotEqual(originals[1])
+
+      restoreSpies()
+
+      expect(targets[0].method).toEqual(originals[0])
+      expect(targets[1].method).toEqual(originals[1])
+    })
+  })
+})
+
+describe('A function that was spied on', function () {
+  const video = {
+    play: function () {}
+  }
+
+  let spy:Spy;
+  beforeEach(function () {
+    spy = spyOn(video, 'play')
+  })
+
+  it('tracks the number of calls', function () {
+    expect(spy.calls.length).toEqual(1)
+  })
+
+  it('tracks the context that was used', function () {
+    expect(spy.calls[0].context).toBe(video)
+  })
+
+  it('tracks the arguments that were used', function () {
+    expect(spy.calls[0].arguments).toEqual([ 'some', 'args' ])
+  })
+
+  it('was called', function () {
+    expect(spy).toHaveBeenCalled()
+  })
+
+  it('was called with the correct args', function () {
+    expect(spy).toHaveBeenCalledWith('some', 'args')
+  })
+
+  it('can be restored', function () {
+    expect(video.play).toEqual(spy)
+    spy.restore()
+    expect(video.play).toNotEqual(spy)
+  })
+})
+
+describe('A function that was spied on but not called', function () {
+  const video = {
+    play: function () {}
+  }
+
+  let spy:Spy;
+  beforeEach(function () {
+    spy = spyOn(video, 'play')
+  })
+
+  it('number of calls to be zero', function () {
+    expect(spy.calls.length).toEqual(0)
+  })
+
+  it('was not called', function () {
+    expect(spy).toNotHaveBeenCalled()
+  })
+})
+
+describe('toBeA', function () {
+  it('requires the value to be a function or string', function () {
+    expect(function () {
+      expect('actual').toBeA(4)
+    }).toThrow(/must be a function or a string/)
+  })
+
+  it('does not throw when the actual value is an instanceof the constructor', function () {
+    expect(function () {
+      expect(new Expectation('foo')).toBeA(Expectation)
+    }).toNotThrow()
+  })
+
+  it('throws when the actual value is not an instanceof the constructor', function () {
+    expect(function () {
+      expect('actual').toBeA(Expectation)
+    }).toThrow(/to be/)
+  })
+
+  it('does not throw when the expected value is the typeof the actual value', function () {
+    expect(function () {
+      expect(4).toBeA('number')
+      expect(NaN).toBeA('number') // hahaha
+    }).toNotThrow()
+  })
+
+  it('throws when the expected value is not the typeof the actual value', function () {
+    expect(function () {
+      expect('actual').toBeA('number')
+    }).toThrow(/to be/)
+  })
+
+  it('does not throw when the actual value is an array', function () {
+    expect(function () {
+      expect([]).toBeAn('array')
+    }).toNotThrow()
+  })
+
+  it('throws when the actual value is not an array', function () {
+    expect(function () {
+      expect('actual').toBeAn('array')
+    }).toThrow(/to be/)
+  })
+})
+
+describe('toBeGreaterThan', function () {
+  it('does not throw when the actual value is greater than the expected value', function () {
+    expect(function () {
+      expect(3).toBeGreaterThan(2)
+    }).toNotThrow()
+  })
+
+  it('throws when the actual value is not greater than the expected value', function () {
+    expect(function () {
+      expect(2).toBeGreaterThan(3)
+    }).toThrow(/to be greater than/)
+  })
+})
+
+
+describe('toBeLessThan', function () {
+  it('does not throw when the actual value is less than the expected value', function () {
+    expect(function () {
+      expect(2).toBeLessThan(3)
+    }).toNotThrow()
+  })
+
+  it('throws when the actual value is not less than the expected value', function () {
+    expect(function () {
+      expect(3).toBeLessThan(2)
+    }).toThrow(/to be less than/)
+  })
+})
+
+describe('toBeTruthy', function () {
+  it('does not throw on truthy actual values', function () {
+    expect(function () {
+      expect(1).toBeTruthy()
+      expect({ hello: 'world' }).toBeTruthy()
+      expect([ 1, 2, 3 ]).toBeTruthy()
+    }).toNotThrow()
+  })
+
+  it('throws on falsy actual values', function () {
+    expect(function () {
+      expect(0).toBeTruthy()
+    }).toThrow()
+
+    expect(function () {
+      expect(null).toBeTruthy()
+    }).toThrow()
+
+    expect(function () {
+      expect(undefined).toBeTruthy()
+    }).toThrow()
+  })
+})
+
+describe('toBeFalsy', function () {
+  it('throws on truthy values', function () {
+    expect(function () {
+      expect(42).toBeFalsy()
+    }).toThrow()
+
+    expect(function () {
+      expect({ foo: 'bar' }).toBeFalsy()
+    }).toThrow()
+
+    expect(function () {
+      expect([]).toBeFalsy()
+    }).toThrow()
+  })
+
+  it('does not throw with falsy actual values', function () {
+    expect(function () {
+      expect(0).toBeFalsy()
+      expect(null).toBeFalsy()
+      expect(undefined).toBeFalsy()
+    }).toNotThrow()
+  })
+})
+
+describe('toEqual', function () {
+  it('works', function () {
+    expect(function () {
+      expect('actual').toEqual('expected')
+    }).toThrow(/Expected 'actual' to equal 'expected'/)
+  })
+
+  it('works with objects that have the same keys in different order', function () {
+    const a = { a: 'a', b: 'b', c: 'c' }
+    const b = { b: 'b', c: 'c', a: 'a' }
+    expect(a).toEqual(b)
+  })
+
+  it('shows diff', function () {
+    try {
+      expect('actual').toEqual('expected')
+    } catch (err) {
+      expect(err.actual).toEqual('actual')
+      expect(err.expected).toEqual('expected')
+      expect(err.showDiff).toEqual(true)
+    }
+  })
+})
+
+describe('toExclude', function () {
+  it('requires the actual value to be an array or string', function () {
+    expect(function () {
+      expect(1).toExclude(2)
+    }).toThrow(/must be an array or a string/)
+  })
+
+  it('does not throw when an array does not contain the expected value', function () {
+    expect(function () {
+      expect([ 1, 2, 3 ]).toExclude(4)
+    }).toNotThrow()
+  })
+
+  it('throws when an array contains the expected value', function () {
+    expect(function () {
+      expect([ 1, 2, 3 ]).toExclude(2)
+    }).toThrow(/to exclude/)
+  })
+
+  it('does not throw when an array does not contain the expected value', function () {
+    expect(function () {
+      expect('hello world').toExclude('goodbye')
+    }).toNotThrow()
+  })
+
+  it('throws when a string contains the expected value', function () {
+    expect(function () {
+      expect('hello world').toExclude('hello')
+    }).toThrow(/to exclude/)
+  })
+})
+
+describe('toExist', function () {
+  it('does not throw on truthy actual values', function () {
+    expect(function () {
+      expect(1).toExist()
+      expect({ 'hello': 'world' }).toExist()
+      expect([ 1, 2, 3 ]).toExist()
+    }).toNotThrow()
+  })
+
+  it('throws on falsy actual values', function () {
+    expect(function () {
+      expect(0).toExist()
+    }).toThrow()
+
+    expect(function () {
+      expect(null).toExist()
+    }).toThrow()
+
+    expect(function () {
+      expect(undefined).toExist()
+    }).toThrow()
+  })
+})
+
+describe('toNotExist', function () {
+  it('throws on truthy values', function () {
+    expect(function () {
+      expect(42).toNotExist()
+    }).toThrow()
+
+    expect(function () {
+      expect({ foo: 'bar' }).toNotExist()
+    }).toThrow()
+
+    expect(function () {
+      expect([]).toNotExist()
+    }).toThrow()
+  })
+
+  it('does not throw with falsy actual values', function () {
+    expect(function () {
+      expect(0).toNotExist()
+      expect(null).toNotExist()
+      expect(undefined).toNotExist()
+    }).toNotThrow()
+  })
+})
+
+describe('toInclude', function () {
+  it('requires the actual value to be an array or string', function () {
+    expect(function () {
+      expect(1).toInclude(2)
+    }).toThrow(/must be an array or a string/)
+  })
+
+  it('does not throw when an array contains an expected integer', function () {
+    expect(function () {
+      expect([ 1, 2, 3 ]).toInclude(2)
+      expect([ { a: 1 }, { c: 2 } ]).toInclude({ c: 2 })
+    }).toNotThrow()
+  })
+
+  it('does not throw when an array contains an expected object', function () {
+    expect(function () {
+      expect([ { a: 1 }, { c: 2 } ]).toInclude({ c: 2 })
+    }).toNotThrow()
+  })
+
+  it('throws when an array does not contain an expected integer', function () {
+    expect(function () {
+      expect([ 1, 2, 3 ]).toInclude(4)
+    }).toThrow(/to include/)
+  })
+
+  it('throws when an array does not contain an expected object', function () {
+    expect(function () {
+      expect([ { a: 1 }, { c: 2 } ]).toInclude({ a: 2 })
+    }).toThrow(/to include/)
+  })
+
+  it('does not throw when a string contains the expected value', function () {
+    expect(function () {
+      expect('hello world').toInclude('world')
+    }).toNotThrow()
+  })
+
+  it('throws when a string does not contain the expected value', function () {
+    expect(function () {
+      expect('hello world').toInclude('goodbye')
+    }).toThrow(/to include/)
+  })
+})
+
+describe('toMatch', function () {
+  it('requires the pattern to be a RegExp', function () {
+    expect(function () {
+      expect('actual').toMatch('expected')
+    }).toThrow(/must be a RegExp/)
+  })
+
+  it('does not throw when the actual value matches the pattern', function () {
+    expect(function () {
+      expect('actual').toMatch(/^actual$/)
+    }).toNotThrow()
+  })
+
+  it('throws when the actual value does not match the pattern', function () {
+    expect(function () {
+      expect('actual').toMatch(/nope/)
+    }).toThrow(/to match/)
+  })
+})
+
+describe('toNotMatch', function () {
+  it('requires the pattern to be a RegExp', function () {
+    expect(function () {
+      expect('actual').toNotMatch('expected')
+    }).toThrow(/must be a RegExp/)
+  })
+
+  it('does not throw when the actual value does not match the pattern', function () {
+    expect(function () {
+      expect('actual').toNotMatch(/nope/)
+    }).toNotThrow()
+  })
+
+  it('throws when the actual value matches the pattern', function () {
+    expect(function () {
+      expect('actual').toNotMatch(/^actual$/)
+    }).toThrow(/to not match/)
+  })
+})
+
+describe('toNotEqual', function () {
+  it('works with arrays of objects', function () {
+    const a = [
+      {
+        id: 0,
+        text: 'Array Object 0',
+        boo: false
+      },
+      {
+        id: 1,
+        text: 'Array Object 1',
+        boo: false
+      }
+    ]
+
+    const b = [
+      {
+        id: 0,
+        text: 'Array Object 0',
+        boo: true // value of boo is changed to true here
+      },
+      {
+        id: 1,
+        text: 'Array Object 1',
+        boo: false
+      }
+    ]
+
+    expect(a).toNotEqual(b)
+  })
+
+  if (typeof Map !== 'undefined') {
+    it('works with Map', function () {
+      const a = new Map()
+      a.set('key', 'value')
+
+      const b = new Map()
+      b.set('key', 'another value')
+
+      expect(a).toNotEqual(b)
+    })
+  }
+
+  if (typeof Set !== 'undefined') {
+    it('works with Set', function () {
+      const a = new Set()
+      a.add('a')
+
+      const b = new Set()
+      b.add('b')
+
+      expect(a).toNotEqual(b)
+    })
+  }
+})
+
+describe('withArgs', function () {
+  const fn = function (arg1:any, arg2:any) {
+    if (arg1 === 'first' && typeof arg2 === 'undefined') {
+      throw new Error('first arg found')
+    }
+    if (arg1 === 'first' && arg2 === 'second') {
+      throw new Error('both args found')
+    }
+  }
+
+  it('invokes actual function with args', function () {
+    expect(function () {
+      expect(fn).withArgs('first').toThrow(/first arg found/)
+    }).toNotThrow()
+  })
+
+  it('can be chained', function () {
+    expect(function () {
+      expect(fn).withArgs('first').withArgs('second').toThrow(/both args found/)
+    }).toNotThrow()
+  })
+
+  it('throws when actual is not a function', function () {
+    expect(function () {
+      expect('not a function').withArgs('first')
+    }).toThrow(/must be a function/)
+  })
+})
+
+describe('withContext', function () {
+  const context = {
+    check: true
+  }
+  const fn = function (arg:any) {
+    if (this.check && typeof arg === 'undefined') {
+      throw new Error('context found')
+    }
+    if (this.check && arg === 'good') {
+      throw new Error('context and args found')
+    }
+  }
+
+  it('calls function with context', function () {
+    expect(function () {
+      expect(fn).withContext(context).toThrow(/context found/)
+    }).toNotThrow()
+  })
+
+  it('calls function with context and args', function () {
+    expect(function () {
+      expect(fn).withContext(context).withArgs('good').toThrow(/context and args found/)
+    }).toNotThrow()
+  })
+
+})
diff --git a/expect/expect-tests.ts.tscparams b/expect/expect-tests.ts.tscparams
new file mode 100644
index 000000000..a0f279051
--- /dev/null
+++ b/expect/expect-tests.ts.tscparams
@@ -0,0 +1 @@
+--noImplicitAny --target es6
diff --git a/expect/expect.d.ts b/expect/expect.d.ts
new file mode 100644
index 000000000..8d3cdc0d8
--- /dev/null
+++ b/expect/expect.d.ts
@@ -0,0 +1,88 @@
+// Type definitions for Expect v1.13.4
+// Project: https://github.com/mjackson/expect
+// Definitions by: Justin Reidy <https://github.com/jmreidy/>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+declare module "expect" {
+    export class Expectation {
+      constructor(actual:any);
+      toExist(message?:string):Expectation;
+      toBeTruthy(message?:string):Expectation;
+      toNotExist(message?:string):Expectation;
+      toBeFalsy(message?:string):Expectation;
+      toBe(value:any, message?:string):Expectation;
+      toNotBe(value:any, message?:string):Expectation;
+      toEqual(value:any, message?:string):Expectation;
+      toNotEqual(value:any, message?:string):Expectation;
+      toThrow(value?:any, message?:string):Expectation;
+      toNotThrow(value?:any, message?:string):Expectation;
+      toBeA(value:any, message?:string):Expectation;
+      toBeAn(value:any, message?:string):Expectation;
+      toNotBeA(value:any, message?:string):Expectation;
+      toNotBeAn(value:any, message?:string):Expectation;
+      toMatch(value:any, message?:string):Expectation;
+      toNotMatch(value:any, message?:string):Expectation;
+      toBeLessThan(value:any, message?:string):Expectation;
+      toBeFewerThan(value:any, message?:string):Expectation;
+      toBeGreaterThan(value:any, message?:string):Expectation;
+      toBeMoreThan(value:any, message?:string):Expectation;
+      toInclude(value:any, compareValues?:any, message?:string):Expectation;
+      toContain(value:any, compareValues?:any, message?:string):Expectation;
+      toExclude(value:any, compareValues?:any, message?:string):Expectation;
+      toNotContain(value:any, compareValues?:any, message?:string):Expectation;
+      toHaveBeenCalled(message?:string):Expectation;
+      toHaveBeenCalledWith(...args:Array<any>):Expectation;
+      toNotHaveBeenCalled(message?:string):Expectation;
+      withContext(context:any):Expectation;
+      withArgs(...args:Array<any>):Expectation;
+    }
+
+    export interface Extension {
+      [name:string]:(args?:Array<any>) => void;
+    }
+
+    export interface Call {
+      context: Spy;
+      arguments: Array<any>;
+    }
+
+    export interface Spy {
+      __isSpy:Boolean;
+      calls:Array<Call>;
+      andCall(fn:Function):Spy;
+      andCallThrough():Spy;
+      andThrow(object:Object):Spy;
+      andReturn(value:any):Spy;
+      getLastCall():Call;
+      restore():void;
+      destroy():void;
+    }
+
+    function expectFn(actual:any):Expectation;
+
+    export module expect {
+      export function createSpy(fn?:Function, restore?:Function):Spy;
+      export function spyOn(object:Object, methodName:string):Spy;
+      export function isSpy(object:any):Boolean;
+      export function restoreSpies():void;
+      export function assert(condition:any, messageFormat:string, ...extraArgs:Array<any>):void;
+      export function extend(extension:Extension):void;
+    }
+
+    import createSpy = expect.createSpy;
+    import spyOn = expect.spyOn;
+    import isSpy = expect.isSpy;
+    import restoreSpies = expect.restoreSpies;
+    import assert = expect.assert;
+    import extend = expect.extend;
+
+    export default expectFn;
+    export {
+      createSpy,
+      spyOn,
+      isSpy,
+      restoreSpies,
+      assert,
+      extend
+    }
+}