public void WriteJson() { var converterMock = new Mock<ISerializationConverter>(); var adapter = new JsonNetSerializationConverterAdapter(converterMock.Object); var jsonTextWriter = new JsonTextWriter(new StringWriter(new StringBuilder())); var obj = new {It = "Any"}; var jsonSerializer = JsonSerializer.Create(new JsonSerializerSettings()); adapter.WriteJson(jsonTextWriter, obj, jsonSerializer); converterMock.Verify(c=>c.Convert(obj), Times.Once()); }