Add simple file store backend

CHANGELOG

@@ -1,5 +1,6 @@
 - 0.0.6
 	* Update description
+	* Implement simple file store backend (add only)
 - 0.0.5
 	* Add persistence wrapper
 - 0.0.4

shep/store/file.py

@@ -0,0 +1,33 @@
+# standard imports
+import os
+
+
+class SimpleFileStore:
+
+    def __init__(self, path):
+        self.path = path
+        os.makedirs(self.path, exist_ok=True)
+
+
+    def add(self, v, contents=''):
+        fp = os.path.join(self.path, v)
+        try:
+            os.stat(fp)
+            raise FileExistsError(fp)
+        except FileNotFoundError:
+            pass
+        f = open(fp, 'w')
+        f.write(contents)
+        f.close()
+
+
+class SimpleFileStoreFactory:
+
+    def __init__(self, path):
+        self.path = path
+
+
+    def add(self, k):
+        k = str(k)
+        store_path = os.path.join(self.path, k)
+        return SimpleFileStore(store_path)

tests/test_file.py

@@ -0,0 +1,42 @@
+# standard imports
+import unittest
+import tempfile
+import os
+
+# local imports
+from shep.persist import PersistedState
+from shep.store.file import SimpleFileStoreFactory
+from shep.error import (
+        StateExists,
+        StateInvalid,
+        )
+
+
+class TestStateReport(unittest.TestCase):
+        
+    def setUp(self):
+        self.d = tempfile.mkdtemp()
+        self.factory = SimpleFileStoreFactory(self.d)
+        self.states = PersistedState(self.factory.add, 4)
+        self.states.add('foo') 
+        self.states.add('bar') 
+        self.states.add('baz') 
+
+
+    def test_add(self):
+        self.states.put('abcd', self.states.FOO)
+        fp = os.path.join(self.d, 'FOO', 'abcd')
+        f = open(fp, 'r')
+        v = f.read()
+        f.close()
+        self.assertEqual(len(v), 0)
+
+
+    def test_dup(self):
+        self.states.put('abcd', self.states.FOO)
+        with self.assertRaises(FileExistsError):
+            self.states.put('abcd', self.states.FOO)
+       
+
+if __name__ == '__main__':
+    unittest.main()