fix: raise for missing context keys (#231)

Author: xelandernt

tests/providers/test_context_resources.py

@@ -1226,6 +1226,12 @@ def test_fetch_context_item_raises() -> None:
     with pytest.raises(KeyError):
         fetch_context_item("s", raise_on_not_found=True)
 
+    with container_context(global_context={"present": None}):
+        assert fetch_context_item("present", default="fallback") is None
+        with pytest.raises(KeyError, match="Key `missing` not found"):
+            fetch_context_item("missing", raise_on_not_found=True)
+        assert fetch_context_item("missing", default="fallback") == "fallback"
+
 
 def test_context_scope_hash() -> None:
     assert ContextScope("TEST") == ContextScope("TEST")

that_depends/providers/context_resources.py

@@ -241,8 +241,9 @@ def fetch_context_item(key: str, default: typing.Any = None, raise_on_not_found:
         ```
 
     """
-    if context := _get_container_context():
-        return context.get(key, default)
+    context = _get_container_context()
+    if context is not None and key in context:
+        return context[key]
     if raise_on_not_found:
         msg = f"Key `{key}` not found in global context."
         raise KeyError(msg)