diff --git a/mz/mz-tests.ts b/mz/mz-tests.ts
new file mode 100644
index 000000000..abcff6ac6
--- /dev/null
+++ b/mz/mz-tests.ts
@@ -0,0 +1,241 @@
+/// <reference path="../mocha/mocha.d.ts" />
+/// <reference path="../node/node.d.ts" />
+/// <reference path="mz.d.ts" />
+
+
+import assert = require('assert')
+import fs = require('mz/fs')
+
+
+describe('fs', function () {
+
+  it('.stat()', function (done) {
+    fs.stat(__filename).then(function (stats) {
+      assert.equal(typeof stats.size, 'number')
+      done()
+    }).catch(done)
+  })
+
+  it('.statSync()', function () {
+    var stats = fs.statSync(__filename)
+    assert.equal(typeof stats.size, 'number')
+  })
+
+  it('.exists()', function (done) {
+    fs.exists(__filename).then(function (exists) {
+      assert(exists)
+      done()
+    }).catch(done)
+  })
+
+  it('.existsSync()', function () {
+    var exists = fs.existsSync(__filename)
+    assert(exists)
+  })
+
+  describe('callback support', function () {
+    it('.stat()', function (done) {
+      fs.stat(__filename, function (err, stats) {
+        assert(!err)
+        assert.equal(typeof stats.size, 'number')
+        done()
+      })
+    })
+
+    it('.exists()', function (done) {
+      fs.exists(__filename, function (err, exists) {
+        assert(!err)
+        assert(exists)
+        done()
+      })
+    })
+  })
+})
+
+import cp = require('mz/child_process')
+describe('child_process', function () {
+
+
+  it('.exec().then()', function (done) {
+    cp.exec('node --version').then(function (params) {
+      assert.equal(params[0].toString('utf8')[0], 'v')
+      done()
+    })
+  })
+
+  it('.exec().catch()', function (done) {
+    cp.exec('lkajsdfkljalskdfjalsdf').catch(function (err) {
+      done()
+    })
+  })
+
+  describe('callback support', function () {
+    it('.exec() success', function (done) {
+      cp.exec('node --version', function (err, stdout) {
+        assert.equal(stdout.toString('utf8')[0], 'v')
+        done()
+      })
+    })
+
+    it('.exec() err', function (done) {
+      cp.exec('lkajsdfkljalskdfjalsdf', function (err) {
+        assert(err)
+        done()
+      })
+    })
+  })
+})
+
+import crypto = require('mz/crypto')
+
+describe('crypto', function () {
+
+  it('.randomBytes().then()', function (done) {
+    crypto.randomBytes(8).then(function (buf) {
+      assert.equal(buf.length, 8)
+      done()
+    })
+  })
+
+  describe('callback support', function () {
+    it('.randomBytes()', function (done) {
+      crypto.randomBytes(8, function (err, buf) {
+        assert(!err)
+        assert.equal(buf.length, 8)
+        done()
+      })
+    })
+  })
+})
+
+import stream = require('stream')
+import readline = require('mz/readline')
+
+describe('readline', function () {
+
+
+  it('.question().then()', function (done) {
+    var input = new stream.PassThrough()
+    var output = new stream.PassThrough()
+    var rl = readline.createInterface({ input: input, output: output })
+
+    rl.question('a').then(function (answer) {
+      assert.equal(answer, 'b')
+      done()
+    })
+
+    assert.equal(output.read(), 'a')
+    input.write('b\n')
+  })
+
+  it('completer support', function (done) {
+    function completer (line:string) {
+      assert.equal(line, 'b')
+      return Promise.resolve([['bTESTSTRING'], line])
+    }
+
+    var input = new stream.PassThrough()
+    var output = new stream.PassThrough()
+    var bufferedOutput = ''
+    var rl = readline.createInterface( input, output, <readline.Completer>completer, true )
+
+    rl.question('a').then(function (answer: string) {
+      assert.equal(answer, 'bTESTSTRING')
+      done()
+    })
+
+    function onOutputData (data: Buffer | String) {
+      bufferedOutput += data.toString()
+
+      if (bufferedOutput.match(/TESTSTRING/)) {
+        input.write('\n')
+        output.removeListener('data', onOutputData)
+      }
+    }
+
+    output.on('data', onOutputData)
+    input.write('b\t')
+  })
+
+  describe('callback support', function () {
+    it('.question()', function (done) {
+      var input = new stream.PassThrough()
+      var output = new stream.PassThrough()
+      var rl = readline.createInterface({ input: input, output: output })
+
+      rl.question('a', function (answer) {
+        assert.equal(answer, 'b')
+        done()
+      })
+
+      assert.equal(output.read(), 'a')
+      input.write('b\n')
+    })
+
+    it('completer support sync', function (done) {
+      function completer (line: string) {
+        assert.equal(line, 'b')
+        return <[string[], string]>[['bTESTSTRING'], line]
+      }
+
+      var input = new stream.PassThrough()
+      var output = new stream.PassThrough()
+      var rl = readline.createInterface(input, output, <readline.Completer>completer, true)
+
+      rl.question('a').then(function (answer) {
+        assert.ok(output.read().toString().match(/TESTSTRING/))
+        done()
+      })
+
+      input.write('b\t\n')
+    })
+
+    it('completer support async', function (done) {
+      function completer (line: string, cb: (err: any, result: [string[], string]) => void) {
+        assert.equal(line, 'b')
+        cb(null, [['bTESTSTRING'], line])
+      }
+
+      var input = new stream.PassThrough()
+      var output = new stream.PassThrough()
+      var rl = readline.createInterface(input, output, <readline.Completer>completer, true )
+
+      rl.question('a').then(function (answer) {
+        assert.ok(output.read().toString().match(/TESTSTRING/))
+        done()
+      })
+
+      input.write('b\t\n')
+    })
+  })
+})
+
+import zlib = require('mz/zlib')
+
+describe('zlib', function () {
+
+  it('.gzip().then().gunzip()', function (done) {
+    var buf = new Buffer("lol", 'utf-8');
+    zlib.gzip(buf).then(function (res) {
+      return zlib.gunzip(res)
+    }).then(function (string) {
+      assert.equal(string, 'lol')
+      done()
+    })
+  })
+
+  describe('callback support', function () {
+    it('.gzip() and .gunzip()', function (done) {
+    var buf = new Buffer("lol", 'utf-8');
+      zlib.gzip(buf, function (err, res) {
+        assert(!err)
+        assert(Buffer.isBuffer(res))
+        zlib.gunzip(res, function (err, string) {
+          assert(!err)
+          assert.equal(string, 'lol')
+          done()
+        })
+      })
+    })
+  })
+})