First commit, basic config (with db) and app handler

this has 100% test coverage and i intend to keep it that way.  api
docs have a good start but still need narrative.  several more things
must be added before i can seriously consider incorporating into
rattail but this seemed a good save point

tests/db/test_sess.py

@@ -0,0 +1,54 @@
+# -*- coding: utf-8; -*-
+
+from unittest import TestCase
+from unittest.mock import MagicMock
+
+import sqlalchemy as sa
+from sqlalchemy import orm
+
+from wuttjamaican.db import sess
+from wuttjamaican.conf import WuttaConfig
+
+
+class TestShortSession(TestCase):
+
+    def test_none(self):
+        with sess.short_session() as s:
+            self.assertIsInstance(s, sess.Session.class_)
+
+    def test_factory(self):
+        TestSession = orm.sessionmaker()
+        with sess.short_session(factory=TestSession) as s:
+            self.assertIsInstance(s, TestSession.class_)
+
+    def test_instance(self):
+        # nb. nothing really happens if we provide the session instance
+        session = MagicMock()
+        with sess.short_session(session=session) as s:
+            pass
+        session.commit.assert_not_called()
+        session.close.assert_not_called()
+
+    def test_config(self):
+        config = MagicMock()
+        TestSession = orm.sessionmaker()
+        config.get_app.return_value.make_session = TestSession
+        # nb. config may be first arg (or kwarg)
+        with sess.short_session(config) as s:
+            self.assertIsInstance(s, TestSession.class_)
+
+    def test_without_commit(self):
+        session = MagicMock()
+        TestSession = MagicMock(return_value=session)
+        with sess.short_session(factory=TestSession, commit=False) as s:
+            pass
+        session.commit.assert_not_called()
+        session.close.assert_called_once_with()
+
+    def test_with_commit(self):
+        session = MagicMock()
+        TestSession = MagicMock(return_value=session)
+        with sess.short_session(factory=TestSession, commit=True) as s:
+            pass
+        session.commit.assert_called_once_with()
+        session.close.assert_called_once_with()