--- a/CHANGES.txt	Sun Mar 18 14:21:48 2018 +0100
+++ b/CHANGES.txt	Sun Mar 18 14:44:41 2018 +0100
@@ -1,7 +1,7 @@
 .. -*- coding: utf-8; mode: rst; -*-
 
 ..
-.. Valid tags: doc, feature, bugfix
+.. Valid tags: doc, feature, bugfix, test
 
 .. _changelog:
 
@@ -17,7 +17,12 @@
    .. change::
       :tags: doc
 
-      Begin the documentation with `Sphinx <http://www.sphinx-doc.org>`_.
+      Begin the documentation with `Sphinx <http://www.sphinx-doc.org>`_
+
+   .. change::
+      :tags: test
+
+      Begin formal unittests
 
 .. changelog::
    :version: 0.5

--- a/MANIFEST.in	Sun Mar 18 14:21:48 2018 +0100
+++ b/MANIFEST.in	Sun Mar 18 14:44:41 2018 +0100
@@ -1,3 +1,5 @@
 include .hg* *.txt requirement*
-recursive-include doc *.*
+graft doc
+graft tests
 prune doc/_build
+global-exclude *.pyc *.pyo

--- a/doc/conf.py	Sun Mar 18 14:21:48 2018 +0100
+++ b/doc/conf.py	Sun Mar 18 14:44:41 2018 +0100
@@ -209,4 +209,4 @@
 
 # -- Options for changelog ---------------------------------------------------
 
-changelog_inner_tag_sort = ['feature', 'bugfix', 'doc']
+changelog_inner_tag_sort = ['feature', 'bugfix', 'test', 'doc']

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/data/conf1.ini	Sun Mar 18 14:44:41 2018 +0100
@@ -0,0 +1,8 @@
+# -*- coding: utf-8 -*-
+
+[config]
+key1 = the value
+key2 = :int:2
+key3 = :float:5.7
+key4 = :bool:yes
+key5 = :bool:off

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/data/conf1.py	Sun Mar 18 14:44:41 2018 +0100
@@ -0,0 +1,7 @@
+# -*- coding: utf-8 -*-
+
+key1 = u"the value"
+key2 = 2
+key3 = 5.7
+key4 = True
+key5 = False

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/data/conf1.yml	Sun Mar 18 14:44:41 2018 +0100
@@ -0,0 +1,9 @@
+# -*- coding: utf-8; mode: yaml; indent-tabs-mode: nil; -*-
+%YAML 1.1
+---
+
+key1: the value
+key2: 2
+key3: 5.7
+key4: true
+key5: false

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/data/conf2.py	Sun Mar 18 14:44:41 2018 +0100
@@ -0,0 +1,6 @@
+# -*- coding: utf-8 -*-
+
+__all__ = ["key1", "nonexistingkey"]
+
+key1 = u"the next value"
+key2 = "non-exported value"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/data/conf3.py	Sun Mar 18 14:44:41 2018 +0100
@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+
+key1 = u"the next value "
+_key2 = "non-exported value"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test.py	Sun Mar 18 14:44:41 2018 +0100
@@ -0,0 +1,69 @@
+# -*- coding: utf-8 -*-
+
+import sys
+import os
+import unittest
+
+sys.path.insert(
+    0,
+    os.path.abspath(
+        os.path.normpath(os.path.join(os.path.dirname(__file__), ".."))))
+
+import configmix
+import configmix.ini
+import configmix.yaml
+import configmix.py
+from configmix.compat import u
+
+
+TESTDATADIR = os.path.join(
+    os.path.abspath(os.path.dirname(__file__)),
+    "data")
+
+
+class T01Basic(unittest.TestCase):
+
+    """Check with low-level internal interfaces"""
+
+    def __check_types(self, cfg):
+        self.assertEqual(u("the value"),
+                         cfg.get("key1"))
+        self.assertTrue(isinstance(cfg.get("key1"), type(u(''))))
+        self.assertEqual(2, cfg.get("key2"))
+        self.assertEqual(5.7, cfg.get("key3"))
+        self.assertTrue(isinstance(cfg.get("key1"), type(u(''))))
+        self.assertTrue(cfg.get("key4"))
+        self.assertTrue(isinstance(cfg.get("key4"), bool))
+        self.assertFalse(cfg.get("key5"))
+        self.assertTrue(isinstance(cfg.get("key5"), bool))
+
+    def test01_ini_types(self):
+        cfg = configmix.ini.load(os.path.join(TESTDATADIR, "conf1.ini"))
+        self.__check_types(cfg)
+
+    def test02_py_types(self):
+        cfg = configmix.py.load(os.path.join(TESTDATADIR, "conf1.py"))
+        self.__check_types(cfg)
+
+    def test03_yaml_types(self):
+        with open(os.path.join(TESTDATADIR, "conf1.yml"), "rt") as f:
+            cfg = configmix.yaml.safe_load(f)
+            self.__check_types(cfg)
+
+    def test04_py_export_all(self):
+        # When __all__ is given only it's keys are exported
+        cfg = configmix.py.load(os.path.join(TESTDATADIR, "conf2.py"))
+        self.assertEqual(u("the next value"), cfg.get("key1"))
+        self.assertTrue(isinstance(cfg.get("key1"), type(u(''))))
+        self.assertTrue(cfg.get("key2") is None)
+
+    def test05_py_hide_private(self):
+        # When no __all__ is given all symbols with leading "_" are hidden
+        cfg = configmix.py.load(os.path.join(TESTDATADIR, "conf3.py"))
+        self.assertEqual(u("the next value "), cfg.get("key1"))
+        self.assertTrue(isinstance(cfg.get("key1"), type(u(''))))
+        self.assertTrue(cfg.get("_key2") is None)
+
+
+if __name__ == "__main__":
+    unittest.main()