public async Task WriteStartOperationMessage_RequestIsNull_IsMatch()
        {
            // arrange
            await using var writer = new SocketMessageWriter();
            var operationId = "12f90cc5-2905-4d10-b33a-cb6d8f98a810";


            // act
            Exception?ex =
                Record.Exception(() => writer.WriteStartOperationMessage(operationId, null !));

            // assert
            Assert.IsType <ArgumentNullException>(ex);
        }
        public async Task WriteStartOperationMessage_WithOperation_IsMatch()
        {
            // arrange
            await using var writer = new SocketMessageWriter();
            var operationId = "12f90cc5-2905-4d10-b33a-cb6d8f98a810";
            var request     = new OperationRequest("Foo",
                                                   GetHeroQueryDocument.Instance,
                                                   new Dictionary <string, object?>()
            {
                { "Var1", "Value1" }
            });


            // act
            writer.WriteStartOperationMessage(operationId, request);

            // assert
            Encoding.UTF8.GetString(writer.Body.Span).MatchSnapshot();
        }