Fix bug in HStoreField string casting and add a test

Author: Photonios

psqlextra/fields/hstore_field.py

@@ -42,8 +42,8 @@ def get_prep_value(self, value):
                     prep_value[key] = val
                 elif val is not None:
                     prep_value[key] = str(val)
-
-                prep_value[key] = val
+                else:
+                    prep_value[key] = val
 
             value = prep_value
 

tests/test_hstore_field.py

@@ -1,3 +1,5 @@
+import pytest
+
 from psqlextra.fields import HStoreField
 
 
@@ -10,3 +12,17 @@ def test_deconstruct():
 
     for key, value in original_kwargs.items():
         assert new_kwargs[key] == value
+
+
+@pytest.mark.parametrize('input,output', [
+    (dict(key1=1, key2=2), dict(key1='1', key2='2')),
+    (dict(key1='1', key2='2'), dict(key1='1', key2='2')),
+    (dict(key1=1, key2=None, key3='3'), dict(key1='1', key2=None, key3='3')),
+    ([1, 2, 3], ['1', '2', '3']),
+    (['1', '2', '3'], ['1', '2', '3']),
+])
+def test_get_prep_value(input, output):
+    """Tests whether the :see:HStoreField's get_prep_value
+    method works properly."""
+
+    assert HStoreField().get_prep_value(input) == output