public void AddJsonConverter_registersJsonSerializerOptions() { var services = new ServiceCollection(); var builder = new SerializerBuilder(services); builder.AddJsonConverter <JsonStringEnumConverter>(); services.Should().ContainEquivalentOf( new { ServiceType = typeof(JsonStringEnumConverter), ImplementationType = typeof(JsonStringEnumConverter) }); services.BuildServiceProvider().GetService <IOptions <JsonSerializerOptions> >()?.Value .Should().BeEquivalentTo(new JsonSerializerOptions { Converters = { new JsonStringEnumConverter() } }); }