Fixed default parameters matching to support None as a default parameter value

punq/__init__.py

@@ -197,12 +197,13 @@ def _match_defaults(spec):
         # Defaults for args are just a tuple. We match args with their defaults
         # by position, starting at the first defaulted arg
         offset = len(spec.args) - len(spec.defaults)
-        defaults = ([None] * offset) + list(spec.defaults)
+        defaults = ([empty] * offset) + list(spec.defaults)
 
-        ns = {key: value for key, value in zip(spec.args, defaults) if value is not None}
+        # filter only args with default value presented
+        ns = {key: value for key, value in zip(spec.args, defaults) if value is not empty}
 
     if spec.kwonlydefaults is not None:
-        # defaults for kwargs are in a dict, so we just update the result dict.
+        # defaults for kwargs are in a dict, so we just update the result dict
         ns.update(spec.kwonlydefaults)
 
     return ns
@@ -491,7 +492,7 @@ def _build_impl(self, registration, resolution_args, context):
 
         args = _match_defaults(spec)
         args.update({
-            k: self._resolve_impl(v, resolution_args, context, args.get(k))
+            k: self._resolve_impl(v, resolution_args, context, args.get(k, empty))
             for k, v in registration.needs.items()
             if k != "return" and k not in registration.args and k not in resolution_args
         })
@@ -516,7 +517,7 @@ def _should_auto_register(self, service_key, registration):
             return False
         return registration is None and inspect.isclass(service_key)
 
-    def _resolve_impl(self, service_key, kwargs, context, default=None):
+    def _resolve_impl(self, service_key, kwargs, context, default=empty):
         context = self.registrations.build_context(service_key, context)
 
         if service_key in self._singletons:
@@ -532,7 +533,7 @@ def _resolve_impl(self, service_key, kwargs, context, default=None):
 
         registration = target.next_impl()
 
-        if registration is None and default is not None:
+        if registration is None and default is not empty:
             return default
 
         if self._should_auto_register(service_key, registration):

tests/test_kwarg_defaults.py

@@ -8,9 +8,10 @@ class Dep:
 
 
 class Client:
-    def __init__(self, a: Dep, b: int = 10):
+    def __init__(self, a: Dep, b: int = 10, c: str | None = None):
         self.a = a
         self.b = b
+        self.c = c
 
 
 def test_can_create_instance_with_defaulted_kwarg():
@@ -20,6 +21,7 @@ def test_can_create_instance_with_defaulted_kwarg():
 
     client = container.resolve(Client)
     expect(client.b).to(equal(10))
+    expect(client.c).to(equal(None))
 
 
 def test_defaults_are_superseded_by_registrations():
@@ -30,12 +32,14 @@ def test_defaults_are_superseded_by_registrations():
 
     client = container.resolve(Client)
     expect(client.b).to(equal(3))
+    expect(client.c).to(equal(None))
 
 
 def test_defaults_are_superseded_by_context():
     container = Container()
     container.register(Dep)
     container.register(Client)
 
-    client = container.resolve(Client, b=5)
+    client = container.resolve(Client, b=5, c="win")
     expect(client.b).to(equal(5))
+    expect(client.c).to(equal("win"))