Using google.protobuf.Empty as response results in a bad gRPC response #618

@StefH commented on GitHub (Jul 29, 2024):

@ArcaneTSGK
I was thinking, are there any other predefined types in google?

And what should actually be the behavior of WireMock.Net if a google.protobuf.Empty is a return value?
Is this just an empty response?

@StefH commented on GitHub (Jul 29, 2024): @ArcaneTSGK I was thinking, are there any other predefined types in google? And what should actually be the behavior of WireMock.Net if a google.protobuf.Empty is a return value? Is this just an empty response?

adam commented

https://protobuf.dev/reference/protobuf/google.protobuf/

@ArcaneTSGK commented on GitHub (Jul 29, 2024):

@StefH There are a number of them yes,

For Empty return value it's Empty {} it's because protobuf does not allow you to request/response with null / no body like a typical REST API would.

Converting Empty to JSON would represent an empty JSON object {}

Here are all of Googles Well Known types:

https://protobuf.dev/reference/protobuf/google.protobuf/#empty

Returning any of the scalar types in protobuf within a custom response that maps to a C# type is fine except for 'Enum'. I've not tried the 'Any' well-known type as my application doesn't have use for it, but I imagine that one might cause some issues, also when working with nullable types you use 'OneOf', again I haven't had to use these so I do not know if they'll work, but this is what a proto file would look like using those:

Usage of 'Any'

syntax = "proto3";

package tutorial;

import "include/google/protobuf/any.proto"

message Animal {
	string name=1;
	int32 age=2;
	google.protobuf.Any care_giver=3;
}

message Owner {
	int32 id=1;
	string first_name=2;
	string last_name=3;
}

message Foster {
	int32 id=1;
	string address=2;
}

In that example a care give can be any pre-defined message in the proto, which could be Owner or the Foster, so that might be a test case for Wiremock to see if Any maps back, and lastly OneOf for nullables where you'd need to be able to allow a null return in the response:

And this is OneOf

import "google/protobuf/struct.proto";

package tutorial;

option csharp_namespace = "MyExample.Dog";

message Dog {
	google.protobuf.Int32Value id=1;
	string name=2;
	NullableField profile_picture=3;
}

message NullableField {
	oneof kind {
		google.protobuf.NullValue null=1;
		google.protobuf.StringValue value=2;
	}
}

@ArcaneTSGK commented on GitHub (Jul 29, 2024): @StefH There are a number of them yes, For Empty return value it's `Empty {}` it's because protobuf does not allow you to request/response with null / no body like a typical REST API would. Converting Empty to JSON would represent an empty JSON object {} Here are all of Googles Well Known types: https://protobuf.dev/reference/protobuf/google.protobuf/ https://protobuf.dev/reference/protobuf/google.protobuf/#empty Returning any of the scalar types in protobuf within a custom response that maps to a C# type is fine except for 'Enum'. I've not tried the 'Any' well-known type as my application doesn't have use for it, but I imagine that one might cause some issues, also when working with nullable types you use 'OneOf', again I haven't had to use these so I do not know if they'll work, but this is what a proto file would look like using those: Usage of 'Any' ``` protobuf syntax = "proto3"; package tutorial; import "include/google/protobuf/any.proto" message Animal { string name=1; int32 age=2; google.protobuf.Any care_giver=3; } message Owner { int32 id=1; string first_name=2; string last_name=3; } message Foster { int32 id=1; string address=2; } ``` In that example a care give can be any pre-defined message in the proto, which could be Owner or the Foster, so that might be a test case for Wiremock to see if Any maps back, and lastly OneOf for nullables where you'd need to be able to allow a null return in the response: And this is OneOf ``` protobuf import "google/protobuf/struct.proto"; package tutorial; option csharp_namespace = "MyExample.Dog"; message Dog { google.protobuf.Int32Value id=1; string name=2; NullableField profile_picture=3; } message NullableField { oneof kind { google.protobuf.NullValue null=1; google.protobuf.StringValue value=2; } } ```

adam commented

@StefH commented on GitHub (Jul 30, 2024):

Currently I only have an easy way to support:

google.protobuf.Empty
google.protobuf.Duration
google.protobuf.Timestamp

@StefH commented on GitHub (Jul 30, 2024): Currently I only have an easy way to support: - google.protobuf.Empty - google.protobuf.Duration - google.protobuf.Timestamp

adam commented

https://github.com/StefH/ProtoBufJsonConverter/pull/18

@StefH commented on GitHub (Aug 4, 2024):

@StefH commented on GitHub (Aug 4, 2024): https://github.com/StefH/ProtoBufJsonConverter/pull/18

adam commented

@StefH commented on GitHub (Aug 4, 2024):

@ArcaneTSGK
If you have time, you can use this preview version: 1.5.62-ci-19066

@StefH commented on GitHub (Aug 4, 2024): @ArcaneTSGK If you have time, you can use this preview version: 1.5.62-ci-19066

adam commented

@StefH commented on GitHub (Aug 15, 2024):

@ArcaneTSGK
Can you please test preview 1.5.62-ci-19067 , this version supports:

google.protobuf.Empty
google.protobuf.Duration
google.protobuf.Timestamp
google/protobuf/wrappers
google/protobuf/any
google/protobuf/struct
Enum
oneof

@StefH commented on GitHub (Aug 15, 2024): @ArcaneTSGK Can you please test preview 1.5.62-ci-19067 , this version supports: - google.protobuf.Empty - google.protobuf.Duration - google.protobuf.Timestamp - google/protobuf/wrappers - google/protobuf/any - google/protobuf/struct - Enum - `oneof`

adam commented

@ArcaneTSGK commented on GitHub (Aug 15, 2024):

@ArcaneTSGK Can you please test preview 1.5.62-ci-19067 , this version supports:

google.protobuf.Empty

google.protobuf.Duration

google.protobuf.Timestamp

google/protobuf/wrappers

google/protobuf/any

google/protobuf/struct

Enum

oneof

I will have some time tomorrow to take a look, I'll let you know my results, thanks @StefH

@ArcaneTSGK commented on GitHub (Aug 15, 2024): > @ArcaneTSGK Can you please test preview 1.5.62-ci-19067 , this version supports: > > * google.protobuf.Empty > * google.protobuf.Duration > * google.protobuf.Timestamp > * google/protobuf/wrappers > * google/protobuf/any > * google/protobuf/struct > * Enum > * `oneof` I will have some time tomorrow to take a look, I'll let you know my results, thanks @StefH

adam commented

2025-12-29 15:28:36 +01:00

@StefH commented on GitHub (Aug 22, 2024):

@ArcaneTSGK
Did you have some time to check?

@StefH commented on GitHub (Aug 22, 2024): @ArcaneTSGK Did you have some time to check?

adam commented

@StefH commented on GitHub (Aug 27, 2024):

@ArcaneTSGK
Did you have some time to check?

@StefH commented on GitHub (Aug 27, 2024): @ArcaneTSGK Did you have some time to check?

adam commented

2025-12-29 15:28:36 +01:00

@ArcaneTSGK commented on GitHub (Aug 31, 2024):

Hi @StefH sorry for the delay,

Unfortunately, I can't install your prerelease version 1.5.62-ci-19067 as it does not resolve, are your pre-releases publicly available?

I only have the option (with prereleases enabled) to install 1.5.62 or 1.60 / 1.61

@ArcaneTSGK commented on GitHub (Aug 31, 2024): Hi @StefH sorry for the delay, Unfortunately, I can't install your prerelease version 1.5.62-ci-19067 as it does not resolve, are your pre-releases publicly available? I only have the option (with prereleases enabled) to install 1.5.62 or 1.60 / 1.61

adam commented

2025-12-29 15:28:36 +01:00

@StefH commented on GitHub (Aug 31, 2024):

Preview versions are defined on MyGet.
See https://github.com/WireMock-Net/WireMock.Net/wiki/MyGet-preview-versions

But it could be that that specific version is automatically deleted because only x versions are kept on MyGet.

I will take a look and maybe I need to build a new preview.

@StefH commented on GitHub (Aug 31, 2024): Preview versions are defined on MyGet. See https://github.com/WireMock-Net/WireMock.Net/wiki/MyGet-preview-versions But it could be that that specific version is automatically deleted because only x versions are kept on MyGet. I will take a look and maybe I need to build a new preview.

adam commented

2025-12-29 15:28:37 +01:00

@ArcaneTSGK commented on GitHub (Aug 31, 2024):

Preview versions are defined on MyGet. See https://github.com/WireMock-Net/WireMock.Net/wiki/MyGet-preview-versions

But it could be that that specific version is automatically deleted because only x versions are kept on MyGet.

I will take a look and maybe I need to build a new preview.

No worries, I've added MyGet as a feed and will await the specific version with the gRPC fix to test

@ArcaneTSGK commented on GitHub (Aug 31, 2024): > Preview versions are defined on MyGet. See https://github.com/WireMock-Net/WireMock.Net/wiki/MyGet-preview-versions > > But it could be that that specific version is automatically deleted because only x versions are kept on MyGet. > > I will take a look and maybe I need to build a new preview. No worries, I've added MyGet as a feed and will await the specific version with the gRPC fix to test

adam commented

2025-12-29 15:28:37 +01:00

@StefH commented on GitHub (Aug 31, 2024):

@ArcaneTSGK
Preview version on MyGet for this fix should be : 1.6.1-ci-19109

@StefH commented on GitHub (Aug 31, 2024): @ArcaneTSGK Preview version on MyGet for this fix should be : `1.6.1-ci-19109`

adam commented

2025-12-29 15:28:37 +01:00

@ArcaneTSGK commented on GitHub (Sep 2, 2024):

@StefH

So I attempted to use this build and I get the following exception:

(Status(StatusCode="Internal", Detail="Failed to deserialize response message.")

The proto file looks like this

syntax = "proto3";

import "google/protobuf/empty.proto";

package communication.api.v1;

message SendEmailRequest {
  string email_address = 1;
}

service CommunicationService {
  rpc SendEmail(SendEmailRequest) returns (google.protobuf.Empty);
}

The test is setup as follows:

public void SetupSendEmail()
{
    _server!.AddProtoDefinition(ProtoDefinitionId, CommunicationProtoFile)
        .Given(Request.Create()
            .UsingPost()
            .WithHttpVersion("2")
            .WithPath("/communication.api.v1.CommunicationService/SendEmail")
            .WithBodyAsProtoBuf("communication.api.v1.SendEmailRequest"))
        .WithProtoDefinition(ProtoDefinitionId)
        .RespondWith(Response.Create()
            .WithHeader("Content-Type", "application/grpc")
            .WithTrailingHeader("grpc-status", "0")
            .WithBodyAsProtoBuf(
                "google.protobuf.Empty",
                new { })
            .WithTransformer());
}

I did try Duration and Timestamp aswell but those were returning unimplemented for me when I was using google.protobuf.Timestamp and google.protobuf.Duration respectively as return types

Let me know if I'm missing anything

I also tried the fully qualified name of Google.Protobuf.WellKnownTypes.Empty as the message type to no avail.

Thanks

@ArcaneTSGK commented on GitHub (Sep 2, 2024): @StefH So I attempted to use this build and I get the following exception: (Status(StatusCode="Internal", Detail="Failed to deserialize response message.") The proto file looks like this ``` syntax = "proto3"; import "google/protobuf/empty.proto"; package communication.api.v1; message SendEmailRequest { string email_address = 1; } service CommunicationService { rpc SendEmail(SendEmailRequest) returns (google.protobuf.Empty); } ``` The test is setup as follows: ``` public void SetupSendEmail() { _server!.AddProtoDefinition(ProtoDefinitionId, CommunicationProtoFile) .Given(Request.Create() .UsingPost() .WithHttpVersion("2") .WithPath("/communication.api.v1.CommunicationService/SendEmail") .WithBodyAsProtoBuf("communication.api.v1.SendEmailRequest")) .WithProtoDefinition(ProtoDefinitionId) .RespondWith(Response.Create() .WithHeader("Content-Type", "application/grpc") .WithTrailingHeader("grpc-status", "0") .WithBodyAsProtoBuf( "google.protobuf.Empty", new { }) .WithTransformer()); } ``` I did try Duration and Timestamp aswell but those were returning unimplemented for me when I was using `google.protobuf.Timestamp` and `google.protobuf.Duration` respectively as return types Let me know if I'm missing anything I also tried the fully qualified name of Google.Protobuf.WellKnownTypes.Empty as the message type to no avail. Thanks

adam commented

@StefH commented on GitHub (Sep 2, 2024):

Strange, I did add a unit test https://github.com/WireMock-Net/WireMock.Net/blob/bug/1144-protobuf/test/WireMock.Net.Tests/Grpc/WireMockServerTests.Grpc.cs#L104

proto

private const string ProtoDefinitionWithWellKnownTypes = @"
syntax = ""proto3"";

import ""google/protobuf/empty.proto"";
import ""google/protobuf/timestamp.proto"";
import ""google/protobuf/duration.proto"";

service Greeter {
    rpc SayNothing (google.protobuf.Empty) returns (google.protobuf.Empty);
}

message MyMessageTimestamp {
    google.protobuf.Timestamp ts = 1;
}

message MyMessageDuration {
    google.protobuf.Duration du = 1;
}
";

Unit test code:

// Arrange
        var bytes = Convert.FromBase64String("CgRzdGVm");

        using var server = WireMockServer.Start();

        server
            .Given(Request.Create()
                .UsingPost()
                .WithPath("/grpc/Greeter/SayNothing")
                .WithBody(new NotNullOrEmptyMatcher())
            )
            .RespondWith(Response.Create()
                .WithBodyAsProtoBuf(ProtoDefinitionWithWellKnownTypes, "google.protobuf.Empty",
                    new { }
                )
                .WithTrailingHeader("grpc-status", "0")
                .WithTransformer()
            );

        // Act
        var protoBuf = new ByteArrayContent(bytes);
        protoBuf.Headers.ContentType = new MediaTypeHeaderValue("application/grpc-web");

        var client = server.CreateClient();
        var response = await client.PostAsync("/grpc/Greeter/SayNothing", protoBuf);

        // Assert
        response.StatusCode.Should().Be(HttpStatusCode.OK);
        var responseBytes = await response.Content.ReadAsByteArrayAsync();

        Convert.ToBase64String(responseBytes).Should().Be("");

        server.Stop();

What is the difference?

@StefH commented on GitHub (Sep 2, 2024): Strange, I did add a unit test https://github.com/WireMock-Net/WireMock.Net/blob/bug/1144-protobuf/test/WireMock.Net.Tests/Grpc/WireMockServerTests.Grpc.cs#L104 proto ``` c# private const string ProtoDefinitionWithWellKnownTypes = @" syntax = ""proto3""; import ""google/protobuf/empty.proto""; import ""google/protobuf/timestamp.proto""; import ""google/protobuf/duration.proto""; service Greeter { rpc SayNothing (google.protobuf.Empty) returns (google.protobuf.Empty); } message MyMessageTimestamp { google.protobuf.Timestamp ts = 1; } message MyMessageDuration { google.protobuf.Duration du = 1; } "; ``` Unit test code: ``` c# // Arrange var bytes = Convert.FromBase64String("CgRzdGVm"); using var server = WireMockServer.Start(); server .Given(Request.Create() .UsingPost() .WithPath("/grpc/Greeter/SayNothing") .WithBody(new NotNullOrEmptyMatcher()) ) .RespondWith(Response.Create() .WithBodyAsProtoBuf(ProtoDefinitionWithWellKnownTypes, "google.protobuf.Empty", new { } ) .WithTrailingHeader("grpc-status", "0") .WithTransformer() ); // Act var protoBuf = new ByteArrayContent(bytes); protoBuf.Headers.ContentType = new MediaTypeHeaderValue("application/grpc-web"); var client = server.CreateClient(); var response = await client.PostAsync("/grpc/Greeter/SayNothing", protoBuf); // Assert response.StatusCode.Should().Be(HttpStatusCode.OK); var responseBytes = await response.Content.ReadAsByteArrayAsync(); Convert.ToBase64String(responseBytes).Should().Be(""); server.Stop(); ``` What is the difference?

adam commented

@StefH commented on GitHub (Sep 2, 2024):

Also added another test: https://github.com/WireMock-Net/WireMock.Net/blob/bug/1144-protobuf/test/WireMock.Net.Tests/Grpc/WireMockServerTests.Grpc.cs#L144

@StefH commented on GitHub (Sep 2, 2024): Also added another test: https://github.com/WireMock-Net/WireMock.Net/blob/bug/1144-protobuf/test/WireMock.Net.Tests/Grpc/WireMockServerTests.Grpc.cs#L144

adam commented

@ArcaneTSGK commented on GitHub (Sep 3, 2024):

I will have to provide a minimal reproduction solution when I have time, I've tried a few different things and for .Empty I always get the unable to deserialize response, and for duration/timestamp I'm getting the Unimplemented error.

I'll provide a link to the repository and throw something together by the end of the week

@ArcaneTSGK commented on GitHub (Sep 3, 2024): I will have to provide a minimal reproduction solution when I have time, I've tried a few different things and for .Empty I always get the unable to deserialize response, and for duration/timestamp I'm getting the Unimplemented error. I'll provide a link to the repository and throw something together by the end of the week

adam commented

https://github.com/WireMock-Net/WireMock.Net/issues/1153

@StefH commented on GitHub (Sep 5, 2024):

@StefH commented on GitHub (Sep 5, 2024): https://github.com/WireMock-Net/WireMock.Net/issues/1153

adam commented

@StefH commented on GitHub (Sep 5, 2024):

Using https://protobuf.heyenrath.nl/ with your message and google.protobuf.Empty does return an empty byte array

@StefH commented on GitHub (Sep 5, 2024): Using https://protobuf.heyenrath.nl/ with your message and `google.protobuf.Empty` does return an empty byte array ![image](https://github.com/user-attachments/assets/e6305cec-236f-4e69-84a4-7dfa08058c6a)

adam commented

@StefH commented on GitHub (Sep 11, 2024):

Hello @ArcaneTSGK, could you make an example project to demonstrate this issue?

@StefH commented on GitHub (Sep 11, 2024): Hello @ArcaneTSGK, could you make an example project to demonstrate this issue?

adam commented

@StefH commented on GitHub (Sep 17, 2024):

Hello @ArcaneTSGK, could you make an example project to demonstrate this issue?

@StefH commented on GitHub (Sep 17, 2024): Hello @ArcaneTSGK, could you make an example project to demonstrate this issue?

adam commented