diff --git a/expect.js/expect.js-tests.ts b/expect.js/expect.js-tests.ts
new file mode 100644
index 0000000000..098df13bba
--- /dev/null
+++ b/expect.js/expect.js-tests.ts
@@ -0,0 +1,121 @@
+/// <reference path="expect.js.d.ts" />
+
+function test_expect() {
+    expect();
+    expect(1);
+    expect(true);
+    expect({});
+    expect(0);
+}
+
+function test_expect_properties() {
+    expect(0).be.an;
+    expect(0).have.own;
+    expect(0).not.be.an;
+    expect(0).not.have.own;
+    expect(0).not.include;
+    expect(0).not.only.have.own;
+    expect(0).not.to.be;
+    expect(0).not.to.have.own;
+    expect(0).not.to.include;
+    expect(0).not.to.only.have.own;
+    expect(0).only.have.own;
+    expect(0).to.be.an;
+    expect(0).to.have.own;
+    expect(0).to.include;
+    expect(0).to.not.be.an;
+    expect(0).to.not.have.own;
+    expect(0).to.not.include;
+    expect(0).to.not.only.have.own;
+    expect(0).to.only.have.own;
+    expect(0).be
+}
+
+function test_ok() {
+    expect(true).to.be.ok();
+}
+
+function test_be() {
+    expect(1).to.be(1);
+}
+
+function test_equal() {
+    expect(1).to.equal(1);
+}
+
+function test_eql() {
+    expect({ a: 'b' }).to.eql({ a: 'b' });
+}
+
+function test_a() {
+    // string
+    expect(5).to.be.a('number');
+    expect([]).to.be.an('array');
+
+    // constructors
+    expect(5).to.be.a(Number);
+    expect([]).to.be.an(Array);
+}
+
+function test_match() {
+    expect('1.2.3').to.match(/[0-9]+\.[0-9]+\.[0-9]+/);
+}
+
+function test_contain() {
+    // string
+    expect('hello world').to.contain('world');
+    expect('hello world').to.string('world');
+    // any
+    expect([1, 2]).to.contain(1);
+    expect([1, 2]).to.string(1);
+}
+
+function test_length() {
+    expect([1,2,3]).to.have.length(3);
+}
+
+function test_empty() {
+    expect([]).to.be.empty();
+}
+
+function test_property() {
+    expect(window).to.have.property('expect');
+    expect(window).to.have.property('expect', expect);
+}
+
+function test_key() {
+    expect({ a: 'b' }).to.have.key('a');
+    expect({ a: 'b' }).to.include.key('a');
+    expect({ a: 'b', c: 'd' }).to.only.have.keys('a', 'c');
+    expect({ a: 'b', c: 'd' }).to.only.have.keys(['a', 'c']);
+    expect({ a: 'b', c: 'd' }).to.not.only.have.key('a');
+}
+
+function test_throwException() {
+    var fn = () => {};
+    expect(fn).to.throwError();
+    expect(fn).to.throwException(function (e) {
+        expect(e).to.be.a(SyntaxError);
+    });
+    expect(fn).to.throwException(/matches the exception message/);
+    expect(fn).to.not.throwException();
+}
+
+function test_within() {
+    expect(1).to.be.within(0, Infinity);
+}
+
+function test_greaterThan() {
+    expect(5).to.be.greaterThan(3);
+    expect(3).to.be.above(0);
+}
+
+function test_lessThan() {
+    expect(1).to.be.lessThan(3);
+    expect(0).to.be.below(3);
+}
+
+function test_fail() {
+    expect().fail();
+    expect().fail('Custom failure message');
+}
diff --git a/expect.js/expect.js.d.ts b/expect.js/expect.js.d.ts
new file mode 100644
index 0000000000..c4884f07d9
--- /dev/null
+++ b/expect.js/expect.js.d.ts
@@ -0,0 +1,216 @@
+// Type definitions for expect.js 0.2.0
+// Project: https://github.com/LearnBoost/expect.js
+// Definitions by: Teppei Sato <https://github.com/teppeis>
+// DefinitelyTyped: https://github.com/borisyankov/DefinitelyTyped
+
+declare function expect(target?: any): Expect.Root;
+
+module Expect {
+    interface Assertion {
+        /**
+         * Check if the value is truthy
+         */
+        ok();
+
+        /**
+         * Assert that the function throws.
+         *
+         * @param fn callback to match error string against
+         */
+        throwError(fn?: Function);
+
+        /**
+         * Assert that the function throws.
+         *
+         * @param fn callback to match error string against
+         */
+        throwException(fn?: Function);
+
+        /**
+         * Assert that the function throws.
+         *
+         * @param regexp regexp to match error string against
+         */
+        throwError(regexp: RegExp);
+
+        /**
+         * Assert that the function throws.
+         *
+         * @param fn callback to match error string against
+         */
+        throwException(regexp: RegExp);
+
+        /**
+         * Checks if the array is empty.
+         */
+        empty(): Assertion;
+
+        /**
+         * Checks if the obj exactly equals another.
+         */
+        equal(obj: any): Assertion;
+
+        /**
+         * Checks if the obj sortof equals another.
+         */
+        eql(obj: any): Assertion;
+
+        /**
+         * Assert within start to finish (inclusive).
+         *
+         * @param start
+         * @param finish
+         */
+        within(start: number, finish: number): Assertion;
+
+        /**
+         * Assert typeof.
+         */
+        a(type: string): Assertion;
+
+        /**
+         * Assert instanceof.
+         */
+        a(type: Function): Assertion;
+
+        /**
+         * Assert typeof / instanceof.
+         */
+        an: An;
+
+        /**
+         * Assert numeric value above n.
+         */
+        greaterThan(n: number): Assertion;
+
+        /**
+         * Assert numeric value above n.
+         */
+        above(n: number): Assertion;
+
+        /**
+         * Assert numeric value below n.
+         */
+        lessThan(n: number): Assertion;
+
+        /**
+         * Assert numeric value below n.
+         */
+        below(n: number): Assertion;
+
+        /**
+         * Assert string value matches regexp.
+         *
+         * @param regexp
+         */
+        match(regexp: RegExp): Assertion;
+
+        /**
+         * Assert property "length" exists and has value of n.
+         *
+         * @param n
+         */
+        length(n: number): Assertion;
+
+        /**
+         * Assert property name exists, with optional val.
+         *
+         * @param name
+         * @param val
+         */
+        property(name: string, val?: any): Assertion;
+
+        /**
+         * Assert that string contains str.
+         */
+        contain(str: string): Assertion;
+        string(str: string): Assertion;
+
+        /**
+         * Assert that the array contains obj.
+         */
+        contain(obj: any): Assertion;
+        string(obj: any): Assertion;
+
+        /**
+         * Assert exact keys or inclusion of keys by using the `.own` modifier.
+         */
+        key(keys: string[]): Assertion;
+        /**
+         * Assert exact keys or inclusion of keys by using the `.own` modifier.
+         */
+        key(...keys: string[]): Assertion;
+        /**
+         * Assert exact keys or inclusion of keys by using the `.own` modifier.
+         */
+        keys(keys: string[]): Assertion;
+        /**
+         * Assert exact keys or inclusion of keys by using the `.own` modifier.
+         */
+        keys(...keys: string[]): Assertion;
+
+        /**
+         * Assert a failure.
+         */
+        fail(message?: string): Assertion;
+    }
+
+    interface Root extends Assertion {
+        not: Not;
+        to: To;
+        only: Only;
+        have: Have;
+        be: Be;
+    }
+
+    interface Be extends Assertion {
+        /**
+         * Checks if the obj exactly equals another.
+         */
+        (obj: any): Assertion;
+
+        an: An;
+    }
+
+    interface An extends Assertion {
+        /**
+         * Assert typeof.
+         */
+        (type: string): Assertion;
+
+        /**
+         * Assert instanceof.
+         */
+        (type: Function): Assertion;
+    }
+
+    interface Not extends Expect.NotBase {
+        to: Expect.ToBase;
+    }
+
+    interface NotBase extends Assertion {
+        be: Be;
+        have: Have;
+        include: Assertion;
+        only: Only;
+    }
+
+    interface To extends Expect.ToBase {
+        not: Expect.NotBase;
+    }
+
+    interface ToBase extends Assertion {
+        be: Be;
+        have: Have;
+        include: Assertion;
+        only: Only;
+    }
+
+    interface Only extends Assertion {
+        have: Have;
+    }
+
+    interface Have extends Assertion {
+        own: Assertion;
+    }
+}