convert_names_case on default resolvers doesn't work well with directives

[zwangBLP]

For example in the current test

ariadne/tests/test_directives.py

Line 60 in e03d333

def test_field_definition_directive_replaces_field_resolver_with_custom_one():

For simplicity if I change the test case to have both convert_names_case=True and @upper it will fail

def test_field_definition_directive_replaces_field_resolver_with_custom_one():
    type_defs = """
        directive @upper on FIELD_DEFINITION

        type Query {
            test: Custom
        }

        type Custom {
            nodeField: String @upper
        }
    """

    query = QueryType()
    query.set_field("test", lambda *_: {"node_field": "custom"})

    schema = make_executable_schema(
        type_defs,
        [query],
        directives={"upper": UpperDirective},
        convert_names_case=True,
    )

    result = graphql_sync(schema, "{ test { nodeField }}")
    assert result.errors is None
    assert result.data == {"test": {"nodeField": "CUSTOM"}}

python -m pytest tests/test_directives.py::test_field_definition_directive_replaces_field_resolver_with_custom_one

FAILED tests/test_directives.py::test_field_definition_directive_replaces_field_resolver_with_custom_one - assert [GraphQLError("'NoneType' object has no attribute 'upper'", locations=[SourceLocation(line=1, column=10)], path=['test', 'nodeField'])] is None

But if I change the test case to have only convert_names_case=True it will succeed

def test_field_definition_directive_replaces_field_resolver_with_custom_one():
    type_defs = """
        type Query {
            test: Custom
        }

        type Custom {
            nodeField: String
        }
    """

    query = QueryType()
    query.set_field("test", lambda *_: {"node_field": "custom"})

    schema = make_executable_schema(
        type_defs,
        [query],
        convert_names_case=True,
    )

    result = graphql_sync(schema, "{ test { nodeField }}")
    assert result.errors is None
    assert result.data == {"test": {"nodeField": "custom"}}

python -m pytest tests/test_directives.py::test_field_definition_directive_replaces_field_resolver_with_custom_one

1 passed, 2 warnings in 0.04s

It will also succeed if I explicitly provide a resolver when having both convert_names_case=True and @upper

def test_field_definition_directive_replaces_field_resolver_with_custom_one():
    type_defs = """
        directive @upper on FIELD_DEFINITION

        type Query {
            test: Custom
        }

        type Custom {
            nodeField: String @upper
        }
    """

    query = QueryType()
    test =  ObjectType('Custom')
    query.set_field("test", lambda *_: {"node_field": "custom"})
    test.set_field("nodeField", lambda obj, *_: obj["node_field"])

    schema = make_executable_schema(
        type_defs,
        [query, test],
        directives={"upper": UpperDirective},
        convert_names_case=True,
    )

    result = graphql_sync(schema, "{ test { nodeField }}")
    assert result.errors is None
    assert result.data == {"test": {"nodeField": "CUSTOM"}}

python -m pytest tests/test_directives.py::test_field_definition_directive_replaces_field_resolver_with_custom_one

1 passed, 2 warnings in 0.05s