save to filesystem; use autocommit

kv.py

@@ -4,9 +4,11 @@
 
 class KV(MutableMapping):
 
-    def __init__(self):
-        self._db = sqlite3.connect(':memory:')
-        self._execute('CREATE TABLE data (key TEXT PRIMARY KEY, value TEXT)')
+    def __init__(self, db_uri=':memory:'):
+        self._db = sqlite3.connect(db_uri)
+        self._db.isolation_level = None
+        self._execute('CREATE TABLE IF NOT EXISTS data '
+                      '(key TEXT PRIMARY KEY, value TEXT)')
 
     def _execute(self, *args):
         return self._db.cursor().execute(*args)

requirements-dev.txt

@@ -1 +1,2 @@
 nose==1.2.1
+path.py==2.4.1

tests.py

@@ -1,4 +1,6 @@
 import unittest
+import tempfile
+from path import path
 from kv import KV
 
 
@@ -71,3 +73,16 @@ def test_iter_yields_keys(self):
         kv['b'] = 'x'
         kv['c'] = 'x'
         self.assertItemsEqual(kv, ['a', 'b', 'c'])
+
+
+class KVPersistenceTest(unittest.TestCase):
+
+    def setUp(self):
+        self.tmp = path(tempfile.mkdtemp())
+        self.addCleanup(self.tmp.rmtree)
+
+    def test_value_saved_by_one_kv_client_is_read_by_another(self):
+        kv1 = KV(self.tmp / 'kv.sqlite')
+        kv1['a'] = 'b'
+        kv2 = KV(self.tmp / 'kv.sqlite')
+        self.assertEqual(kv2['a'], 'b')