Do not write HTTP headers with SkipResponseBodyEncodeDecode (#3695)

Make it possible for user code to write HTTP headers.

Author: raphael

http/codegen/server_encode_test.go

@@ -85,6 +85,8 @@ func TestEncode(t *testing.T) {
 		{"empty-server-response", testdata.EmptyServerResponseDSL, testdata.EmptyServerResponseEncodeCode},
 		{"empty-server-response-with-tags", testdata.EmptyServerResponseWithTagsDSL, testdata.EmptyServerResponseWithTagsEncodeCode},
 
+		{"skip-response-body-encode-decode", testdata.ResponseEncoderSkipResponseBodyEncodeDecodeDSL, testdata.ResponseEncoderSkipResponseBodyEncodeDecodeCode},
+
 		{"result-with-custom-pkg-type", testdata.ResultWithCustomPkgTypeDSL, testdata.ResultWithCustomPkgTypeEncodeCode},
 		{"result-with-embedded-custom-pkg-type", testdata.EmbeddedCustomPkgTypeDSL, testdata.ResultWithEmbeddedCustomPkgTypeEncodeCode},
 	}

http/codegen/templates/response_encoder.go.tpl

@@ -33,7 +33,9 @@ func {{ .ResponseEncoder }}(encoder func(context.Context, http.ResponseWriter) g
 		{{- end }}
 	{{- else }}
 		{{- with (index .Result.Responses 0) }}
-			w.WriteHeader({{ .StatusCode }})
+			{{- if not $.Method.SkipResponseBodyEncodeDecode }}
+				w.WriteHeader({{ .StatusCode }})
+			{{- end }}
 			return nil
 		{{- end }}
 	{{- end }}

http/codegen/testdata/result_encode_functions.go

@@ -1036,6 +1036,16 @@ func EncodeMethodEmptyServerResponseWithTagsResponse(encoder func(context.Contex
 }
 `
 
+var ResponseEncoderSkipResponseBodyEncodeDecodeCode = `// EncodeMethodResponseEncoderSkipResponse returns an encoder for responses
+// returned by the ServiceResponseEncoderSkip MethodResponseEncoderSkip
+// endpoint.
+func EncodeMethodResponseEncoderSkipResponse(encoder func(context.Context, http.ResponseWriter) goahttp.Encoder) func(context.Context, http.ResponseWriter, any) error {
+	return func(ctx context.Context, w http.ResponseWriter, v any) error {
+		return nil
+	}
+}
+`
+
 var ResultWithCustomPkgTypeEncodeCode = `// EncodeMethodResultWithCustomPkgTypeDSLResponse returns an encoder for
 // responses returned by the ServiceResultWithCustomPkgTypeDSL
 // MethodResultWithCustomPkgTypeDSL endpoint.

http/codegen/testdata/server_dsls.go

@@ -294,3 +294,15 @@ var ServerSkipResponseBodyEncodeDecodeDSL = func() {
 		})
 	})
 }
+
+var ResponseEncoderSkipResponseBodyEncodeDecodeDSL = func() {
+	Service("ServiceResponseEncoderSkip", func() {
+		Method("MethodResponseEncoderSkip", func() {
+			HTTP(func() {
+				GET("/")
+				SkipResponseBodyEncodeDecode()
+				Response(StatusOK)
+			})
+		})
+	})
+}