Replace LambdaContext class with a typed dictionary

Remove LambdaContext class inheritance and update for TypedDict compatibility

- Remove isinstance() checks for LambdaContext in tests
- Update create_test_lambda_context() to return dictionary instead of class instance
- Change test assertions from attribute access to dictionary access
- Update type annotations to work with LambdaContext as TypedDict

Author: FullyTyped

src/aws_durable_execution_sdk_python_testing/invoker.py

@@ -27,7 +27,7 @@
 
 def create_test_lambda_context() -> LambdaContext:
     # Create client context as a dictionary, not as objects
-    # LambdaContext.__init__ expects dictionaries and will create the objects internally
+    # LambdaContext is now a typed dictionary, so we return a dictionary directly
     client_context_dict = {
         "custom": {"test_key": "test_value"},
         "env": {"platform": "test", "make": "test", "model": "test"},
@@ -45,16 +45,16 @@ def create_test_lambda_context() -> LambdaContext:
         "cognitoIdentityPoolId": "us-west-2:test-pool-456",
     }
 
-    return LambdaContext(
-        invoke_id="test-invoke-12345",
-        client_context=client_context_dict,
-        cognito_identity=cognito_identity_dict,
-        epoch_deadline_time_in_ms=int(
+    return {
+        "invoke_id": "test-invoke-12345",
+        "client_context": client_context_dict,
+        "cognito_identity": cognito_identity_dict,
+        "epoch_deadline_time_in_ms": int(
             (time.time() + 900) * 1000
         ),  # 15 minutes from now
-        invoked_function_arn="arn:aws:lambda:us-west-2:123456789012:function:test-function",
-        tenant_id="test-tenant-789",
-    )
+        "invoked_function_arn": "arn:aws:lambda:us-west-2:123456789012:function:test-function",
+        "tenant_id": "test-tenant-789",
+    }
 
 
 class Invoker(Protocol):

tests/invoker_test.py

@@ -26,13 +26,12 @@ def test_create_test_lambda_context():
     """Test creating a test lambda context."""
     context = create_test_lambda_context()
 
-    assert isinstance(context, LambdaContext)
     assert (
-        context.invoked_function_arn
+        context["invoked_function_arn"]
         == "arn:aws:lambda:us-west-2:123456789012:function:test-function"
     )
-    assert context.tenant_id == "test-tenant-789"
-    assert context.client_context is not None
+    assert context["tenant_id"] == "test-tenant-789"
+    assert context["client_context"] is not None
 
 
 def test_in_process_invoker_init():
@@ -98,7 +97,6 @@ def test_in_process_invoker_invoke():
     handler.assert_called_once()
     call_args = handler.call_args[0]
     assert isinstance(call_args[0], DurableExecutionInvocationInputWithClient)
-    assert isinstance(call_args[1], LambdaContext)
 
 
 def test_lambda_invoker_init():