diff --git a/Tests/tester.py b/Tests/tester.py
new file mode 100644
index 000000000..4476aced1
--- /dev/null
+++ b/Tests/tester.py
@@ -0,0 +1,388 @@
+from __future__ import print_function
+
+# require that deprecation warnings are triggered
+import warnings
+warnings.simplefilter('default')
+# temporarily turn off resource warnings that warn about unclosed
+# files in the test scripts.
+try:
+    warnings.filterwarnings("ignore", category=ResourceWarning)
+except NameError:
+    # we expect a NameError on py2.x, since it doesn't have ResourceWarnings.
+    pass
+
+import sys
+py3 = (sys.version_info >= (3, 0))
+
+# some test helpers
+
+_target = None
+_tempfiles = []
+_logfile = None
+
+
+def success():
+    import sys
+    success.count += 1
+    if _logfile:
+        print(sys.argv[0], success.count, failure.count, file=_logfile)
+    return True
+
+
+def failure(msg=None, frame=None):
+    import sys
+    import linecache
+    failure.count += 1
+    if _target:
+        if frame is None:
+            frame = sys._getframe()
+            while frame.f_globals.get("__name__") != _target.__name__:
+                frame = frame.f_back
+        location = (frame.f_code.co_filename, frame.f_lineno)
+        prefix = "%s:%d: " % location
+        line = linecache.getline(*location)
+        print(prefix + line.strip() + " failed:")
+    if msg:
+        print("- " + msg)
+    if _logfile:
+        print(sys.argv[0], success.count, failure.count, file=_logfile)
+    return False
+
+success.count = failure.count = 0
+
+
+# predicates
+
+def assert_true(v, msg=None):
+    if v:
+        success()
+    else:
+        failure(msg or "got %r, expected true value" % v)
+
+
+def assert_false(v, msg=None):
+    if v:
+        failure(msg or "got %r, expected false value" % v)
+    else:
+        success()
+
+
+def assert_equal(a, b, msg=None):
+    if a == b:
+        success()
+    else:
+        failure(msg or "got %r, expected %r" % (a, b))
+
+
+def assert_almost_equal(a, b, msg=None, eps=1e-6):
+    if abs(a-b) < eps:
+        success()
+    else:
+        failure(msg or "got %r, expected %r" % (a, b))
+
+
+def assert_deep_equal(a, b, msg=None):
+    try:
+        if len(a) == len(b):
+            if all([x == y for x, y in zip(a, b)]):
+                success()
+            else:
+                failure(msg or "got %s, expected %s" % (a, b))
+        else:
+            failure(msg or "got length %s, expected %s" % (len(a), len(b)))
+    except:
+        assert_equal(a, b, msg)
+
+
+def assert_greater(a, b, msg=None):
+    if a > b:
+        success()
+    else:
+        failure(msg or "%r unexpectedly not greater than %r" % (a, b))
+
+
+def assert_greater_equal(a, b, msg=None):
+    if a >= b:
+        success()
+    else:
+        failure(
+            msg or "%r unexpectedly not greater than or equal to %r" % (a, b))
+
+
+def assert_less(a, b, msg=None):
+    if a < b:
+        success()
+    else:
+        failure(msg or "%r unexpectedly not less than %r" % (a, b))
+
+
+def assert_less_equal(a, b, msg=None):
+    if a <= b:
+        success()
+    else:
+        failure(
+            msg or "%r unexpectedly not less than or equal to %r" % (a, b))
+
+
+def assert_is_instance(a, b, msg=None):
+    if isinstance(a, b):
+        success()
+    else:
+        failure(msg or "got %r, expected %r" % (type(a), b))
+
+
+def assert_in(a, b, msg=None):
+    if a in b:
+        success()
+    else:
+        failure(msg or "%r unexpectedly not in %r" % (a, b))
+
+
+def assert_match(v, pattern, msg=None):
+    import re
+    if re.match(pattern, v):
+        success()
+    else:
+        failure(msg or "got %r, doesn't match pattern %r" % (v, pattern))
+
+
+def assert_exception(exc_class, func):
+    import sys
+    import traceback
+    try:
+        func()
+    except exc_class:
+        success()
+    except:
+        failure("expected %r exception, got %r" % (
+                exc_class.__name__, sys.exc_info()[0].__name__))
+        traceback.print_exc()
+    else:
+        failure("expected %r exception, got no exception" % exc_class.__name__)
+
+
+def assert_no_exception(func):
+    import sys
+    import traceback
+    try:
+        func()
+    except:
+        failure("expected no exception, got %r" % sys.exc_info()[0].__name__)
+        traceback.print_exc()
+    else:
+        success()
+
+
+def assert_warning(warn_class, func):
+    # note: this assert calls func three times!
+    import warnings
+
+    def warn_error(message, category=UserWarning, **options):
+        raise category(message)
+
+    def warn_ignore(message, category=UserWarning, **options):
+        pass
+    warn = warnings.warn
+    result = None
+    try:
+        warnings.warn = warn_ignore
+        assert_no_exception(func)
+        result = func()
+        warnings.warn = warn_error
+        assert_exception(warn_class, func)
+    finally:
+        warnings.warn = warn  # restore
+    return result
+
+# helpers
+
+from io import BytesIO
+
+
+def fromstring(data):
+    from PIL import Image
+    return Image.open(BytesIO(data))
+
+
+def tostring(im, format, **options):
+    out = BytesIO()
+    im.save(out, format, **options)
+    return out.getvalue()
+
+
+def lena(mode="RGB", cache={}):
+    from PIL import Image
+    im = cache.get(mode)
+    if im is None:
+        if mode == "RGB":
+            im = Image.open("Images/lena.ppm")
+        elif mode == "F":
+            im = lena("L").convert(mode)
+        elif mode[:4] == "I;16":
+            im = lena("I").convert(mode)
+        else:
+            im = lena("RGB").convert(mode)
+    cache[mode] = im
+    return im
+
+
+def assert_image(im, mode, size, msg=None):
+    if mode is not None and im.mode != mode:
+        failure(msg or "got mode %r, expected %r" % (im.mode, mode))
+    elif size is not None and im.size != size:
+        failure(msg or "got size %r, expected %r" % (im.size, size))
+    else:
+        success()
+
+
+def assert_image_equal(a, b, msg=None):
+    if a.mode != b.mode:
+        failure(msg or "got mode %r, expected %r" % (a.mode, b.mode))
+    elif a.size != b.size:
+        failure(msg or "got size %r, expected %r" % (a.size, b.size))
+    elif a.tobytes() != b.tobytes():
+        failure(msg or "got different content")
+    else:
+        success()
+
+
+def assert_image_completely_equal(a, b, msg=None):
+    if a != b:
+        failure(msg or "images different")
+    else:
+        success()
+
+
+def assert_image_similar(a, b, epsilon, msg=None):
+    epsilon = float(epsilon)
+    if a.mode != b.mode:
+        return failure(msg or "got mode %r, expected %r" % (a.mode, b.mode))
+    elif a.size != b.size:
+        return failure(msg or "got size %r, expected %r" % (a.size, b.size))
+    diff = 0
+    try:
+        ord(b'0')
+        for abyte, bbyte in zip(a.tobytes(), b.tobytes()):
+            diff += abs(ord(abyte)-ord(bbyte))
+    except:
+        for abyte, bbyte in zip(a.tobytes(), b.tobytes()):
+            diff += abs(abyte-bbyte)
+    ave_diff = float(diff)/(a.size[0]*a.size[1])
+    if epsilon < ave_diff:
+        return failure(
+            msg or "average pixel value difference %.4f > epsilon %.4f" % (
+                ave_diff, epsilon))
+    else:
+        return success()
+
+
+def tempfile(template, *extra):
+    import os
+    import os.path
+    import sys
+    import tempfile
+    files = []
+    root = os.path.join(tempfile.gettempdir(), 'pillow-tests')
+    try:
+        os.mkdir(root)
+    except OSError:
+        pass
+    for temp in (template,) + extra:
+        assert temp[:5] in ("temp.", "temp_")
+        name = os.path.basename(sys.argv[0])
+        name = temp[:4] + os.path.splitext(name)[0][4:]
+        name = name + "_%d" % len(_tempfiles) + temp[4:]
+        name = os.path.join(root, name)
+        files.append(name)
+    _tempfiles.extend(files)
+    return files[0]
+
+
+# test runner
+
+def run():
+    global _target, _tests, run
+    import sys
+    import traceback
+    _target = sys.modules["__main__"]
+    run = None  # no need to run twice
+    tests = []
+    for name, value in list(vars(_target).items()):
+        if name[:5] == "test_" and type(value) is type(success):
+            tests.append((value.__code__.co_firstlineno, name, value))
+    tests.sort()  # sort by line
+    for lineno, name, func in tests:
+        try:
+            _tests = []
+            func()
+            for func, args in _tests:
+                func(*args)
+        except:
+            t, v, tb = sys.exc_info()
+            tb = tb.tb_next
+            if tb:
+                failure(frame=tb.tb_frame)
+                traceback.print_exception(t, v, tb)
+            else:
+                print("%s:%d: cannot call test function: %s" % (
+                    sys.argv[0], lineno, v))
+                failure.count += 1
+
+
+def yield_test(function, *args):
+    # collect delayed/generated tests
+    _tests.append((function, args))
+
+
+def skip(msg=None):
+    import os
+    print("skip")
+    os._exit(0)  # don't run exit handlers
+
+
+def ignore(pattern):
+    """Tells the driver to ignore messages matching the pattern, for the
+    duration of the current test."""
+    print('ignore: %s' % pattern)
+
+
+def _setup():
+    global _logfile
+
+    import sys
+    if "--coverage" in sys.argv:
+        # Temporary: ignore PendingDeprecationWarning from Coverage (Py3.4)
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore")
+            import coverage
+        cov = coverage.coverage(auto_data=True, include="PIL/*")
+        cov.start()
+
+    def report():
+        if run:
+            run()
+        if success.count and not failure.count:
+            print("ok")
+            # only clean out tempfiles if test passed
+            import os
+            import os.path
+            import tempfile
+            for file in _tempfiles:
+                try:
+                    os.remove(file)
+                except OSError:
+                    pass  # report?
+            temp_root = os.path.join(tempfile.gettempdir(), 'pillow-tests')
+            try:
+                os.rmdir(temp_root)
+            except OSError:
+                pass
+
+    import atexit
+    atexit.register(report)
+
+    if "--log" in sys.argv:
+        _logfile = open("test.log", "a")
+
+
+_setup()