Merge pull request #37 from ikalnytskyi/flaskscopes-fixes

Isolate dependencies between Flask scopes

src/picobox/contrib/flaskscopes.py

@@ -1,5 +1,7 @@
 """Scopes for Flask framework."""
 
+import uuid
+
 import picobox
 import flask
 
@@ -9,17 +11,32 @@ class _flaskscope(picobox.Scope):
 
     _store = None
 
+    def __init__(self):
+        # Both application and request scopes are merely proxies to
+        # corresponding storage objects in Flask. This means multiple
+        # scope instances will share the same storage object under the
+        # hood, and this is not what we want. So we need to generate
+        # some unique key per scope instance and use that key to
+        # distinguish dependencies stored by different scope instances.
+        self._uuid = str(uuid.uuid4())
+
     def set(self, key, value):
         try:
             dependencies = self._store.__dependencies__
         except AttributeError:
             dependencies = self._store.__dependencies__ = {}
+
+        try:
+            dependencies = dependencies[self._uuid]
+        except KeyError:
+            dependencies = dependencies.setdefault(self._uuid, {})
+
         dependencies[key] = value
 
     def get(self, key):
         try:
-            rv = self._store.__dependencies__[key]
-        except AttributeError:
+            rv = self._store.__dependencies__[self._uuid][key]
+        except (AttributeError, KeyError):
             raise KeyError(key)
         return rv
 

tests/contrib/test_flaskscopes.py

@@ -86,6 +86,33 @@ def test_scope_get_keyerror(request, scopename, ctx, supported_key):
             scope.get(supported_key)
 
 
+@pytest.mark.parametrize('scopename, ctx', [
+    ('appscope', 'appcontext'),
+    ('reqscope', 'reqcontext'),
+])
+def test_scope_state_not_leaked(request, scopename, ctx):
+    ctxfn = request.getfixturevalue(ctx)
+
+    scope_a = request.getfixturevalue(scopename)
+    value_a = object()
+
+    scope_b = type(scope_a)()
+    value_b = object()
+
+    with ctxfn():
+        scope_a.set('the-key', value_a)
+        assert scope_a.get('the-key') is value_a
+
+        with pytest.raises(KeyError, match='the-key'):
+            scope_b.get('the-key')
+
+        scope_b.set('the-key', value_b)
+        assert scope_b.get('the-key') is value_b
+
+        scope_a.set('the-key', value_a)
+        assert scope_a.get('the-key') is value_a
+
+
 @pytest.mark.parametrize('scopename, ctx', [
     ('appscope', 'appcontext'),
 ])