diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..c59dc9f
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,11 @@
+language: python
+python:
+    - "3"
+
+install:
+    - pip install tox-travis coveralls
+script:
+    - tox
+
+after_success:
+    - coveralls
diff --git a/Readme.md b/README.md
similarity index 100%
rename from Readme.md
rename to README.md
diff --git a/SecondaryValue/test_secondaryvalue.py b/SecondaryValue/test_secondaryvalue.py
new file mode 100644
index 0000000..70c2a47
--- /dev/null
+++ b/SecondaryValue/test_secondaryvalue.py
@@ -0,0 +1,81 @@
+from SecondaryValue import SecondaryValue
+import random
+from pytest import approx, raises
+import numpy
+
+class TestBasicUsage():
+    def setup(self):
+        self.x = SecondaryValue('a*b+c')
+
+    def test_no_uncertainties(self):
+        # no uncertainties
+        assert 1.2 * 7.9 + 10 == self.x(a=1.2, b=7.9, c=10)
+
+    def test_get_symbols(self):
+        # the right symbols
+        assert self.x.get_symbols() == {'a': {}, 'b': {}, 'c': {}}
+
+    def ret_deps_without_deps(self):
+        # retdeps returns a dict
+        assert self.x(a=1, b=1, c=1, retdeps=True)[1] == {}
+
+    def test_uncertainties(self):
+        # dirty
+        for i in range(100):
+            a, b, c = [(random.random(), random.random()) for _ in range(3)]
+            assert (a[0]*b[0] + c[0], numpy.sqrt((a[0]*b[1])**2 + (a[1]*b[0])**2 + c[1]**2)) \
+                == approx(self.x(a=a, b=b, c=c))
+
+    def test_error_missing(self):
+        with raises(RuntimeError):
+            self.x(u=1)
+
+class TestDependecies():
+    def setup(self):
+        self.x = SecondaryValue('b')
+        self.y = SecondaryValue('a + x', dependencies=dict(x=self.x))
+
+    def test_overwrite(self):
+        result, deps = self.y(a=1, x=1, retdeps=True)
+        assert deps == {}
+        assert result == 2
+
+    def test_dep_calc(self):
+        result, deps = self.y(a=1, b=2, retdeps=True)
+
+        assert result == 3
+        assert deps == {'x': (2, {})}
+
+    def test_dep_calc_err(self):
+        # no retdep
+        for i in range(100):
+            a, b = [(random.random(), random.random()) for _ in range(2)]
+            result, deps = self.y(a=a, b=b, retdeps=True)
+
+            assert (a[0]+b[0], numpy.sqrt((b[1])**2 + (a[1])**2)) \
+                == approx(result)
+
+            assert (b[0], numpy.abs(b[1])) == approx(deps['x'][0])
+
+
+class TestDefaults():
+    def setup(self):
+        self.y = SecondaryValue('a + b', defaults=dict(a=(1, 2)))
+
+    def test_basics(self):
+        assert (2, 2) == self.y(b=1)
+
+class TestShapes():
+    def setup(self):
+        self.x = SecondaryValue('b')
+        self.y = SecondaryValue('a + x', dependencies=dict(x=self.x))
+
+    def test_array_central_value(self):
+        # mixed
+        assert numpy.any(numpy.array([1,2,3]) == self.y(a=([1,2,3],), b=0))
+
+        # both
+        assert numpy.any(2*numpy.array([1,2,3]) \
+                         == self.y(a=([1,2,3],), b=([1,2,3],)))
+
+#    def test_array_uncert(self):
diff --git a/setup.cfg b/setup.cfg
new file mode 100644
index 0000000..05c2ac8
--- /dev/null
+++ b/setup.cfg
@@ -0,0 +1,2 @@
+[tool:pytest]
+addopts = -v -x --ignore=setup.py --ignore=./SecondaryValue/__init__.py --cov=SecondaryValue
diff --git a/setup.py b/setup.py
index fd8687c..af83d18 100644
--- a/setup.py
+++ b/setup.py
@@ -1,8 +1,10 @@
 from setuptools import setup
 
-
+# read the contents of your README file
+from os import path
+this_directory = path.abspath(path.dirname(__file__))
 def readme():
-    with open('Readme.md') as f:
+    with open(path.join(this_directory, 'README.md'), encoding='utf-8') as f:
         return f.read()
 
 setup(name='SecondaryValue',
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..d4efa5f
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,12 @@
+[tox]
+envlist = py3
+
+[testenv]
+commands = pytest
+deps =
+    pytest-pep8
+    pytest-cov
+    pytest
+    coverage
+    numpy
+    sympy