public void finding_open_type_should_add_error_when_no_matching_type_is_found() { var typeDefinition = new GenericTypeDefinition { OpenTypeName = "NotFound", ArgumentTypeNames = new[] { "System.String" } }; var result = ClassUnderTest.findOpenType(typeDefinition); result.ShouldBeNull(); ClassUnderTest.ParseErrors.First().ShouldContain("No generic type matching"); }