Stop marshalling any.Any types unnecessarily.

Fixes #576. Adds a test case for marshalling of details as well.

runtime/BUILD.bazel

@@ -74,6 +74,7 @@ go_test(
         "@com_github_golang_protobuf//ptypes/timestamp:go_default_library",
         "@com_github_golang_protobuf//ptypes/wrappers:go_default_library",
         "@org_golang_google_genproto//protobuf/field_mask:go_default_library",
+        "@org_golang_google_genproto//googleapis/rpc/errdetails:go_default_library",
         "@org_golang_google_grpc//:go_default_library",
         "@org_golang_google_grpc//codes:go_default_library",
         "@org_golang_google_grpc//metadata:go_default_library",

runtime/errors.go

@@ -6,7 +6,6 @@ import (
 	"net/http"
 
 	"github.com/golang/protobuf/proto"
-	"github.com/golang/protobuf/ptypes"
 	"github.com/golang/protobuf/ptypes/any"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/grpclog"
@@ -94,19 +93,9 @@ func DefaultHTTPError(ctx context.Context, mux *ServeMux, marshaler Marshaler, w
 	}
 
 	body := &errorBody{
-		Error: s.Message(),
-		Code:  int32(s.Code()),
-	}
-
-	for _, detail := range s.Details() {
-		if det, ok := detail.(proto.Message); ok {
-			a, err := ptypes.MarshalAny(det)
-			if err != nil {
-				grpclog.Infof("Failed to marshal any: %v", err)
-			} else {
-				body.Details = append(body.Details, a)
-			}
-		}
+		Error:   s.Message(),
+		Code:    int32(s.Code()),
+		Details: s.Proto().GetDetails(),
 	}
 
 	buf, merr := marshaler.Marshal(body)

runtime/errors_test.go

@@ -1,26 +1,32 @@
 package runtime_test
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"strings"
 	"testing"
 
-	"context"
 	"github.com/grpc-ecosystem/grpc-gateway/runtime"
+	"google.golang.org/genproto/googleapis/rpc/errdetails"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
 
 func TestDefaultHTTPError(t *testing.T) {
 	ctx := context.Background()
 
+	statusWithDetails, _ := status.New(codes.FailedPrecondition, "failed precondition").WithDetails(
+		&errdetails.PreconditionFailure{},
+	)
+
 	for _, spec := range []struct {
-		err    error
-		status int
-		msg    string
+		err     error
+		status  int
+		msg     string
+		details string
 	}{
 		{
 			err:    fmt.Errorf("example error"),
@@ -32,10 +38,16 @@ func TestDefaultHTTPError(t *testing.T) {
 			status: http.StatusNotFound,
 			msg:    "no such resource",
 		},
+		{
+			err:     statusWithDetails.Err(),
+			status:  http.StatusPreconditionFailed,
+			msg:     "failed precondition",
+			details: "type.googleapis.com/google.rpc.PreconditionFailure",
+		},
 	} {
 		w := httptest.NewRecorder()
 		req, _ := http.NewRequest("", "", nil) // Pass in an empty request to match the signature
-		runtime.DefaultHTTPError(ctx, &runtime.ServeMux{}, &runtime.JSONBuiltin{}, w, req, spec.err)
+		runtime.DefaultHTTPError(ctx, &runtime.ServeMux{}, &runtime.JSONPb{}, w, req, spec.err)
 
 		if got, want := w.Header().Get("Content-Type"), "application/json"; got != want {
 			t.Errorf(`w.Header().Get("Content-Type") = %q; want %q; on spec.err=%v`, got, want, spec.err)
@@ -53,5 +65,20 @@ func TestDefaultHTTPError(t *testing.T) {
 		if got, want := body["error"].(string), spec.msg; !strings.Contains(got, want) {
 			t.Errorf(`body["error"] = %q; want %q; on spec.err=%v`, got, want, spec.err)
 		}
+
+		if spec.details != "" {
+			details, ok := body["details"].([]interface{})
+			if !ok {
+				t.Errorf(`body["details"] = %T; want %T`, body["details"], []interface{}{})
+				continue
+			}
+			if len(details) != 1 {
+				t.Errorf(`len(body["details"]) = %v; want 1`, len(details))
+				continue
+			}
+			if details[0].(map[string]interface{})["@type"] != spec.details {
+				t.Errorf(`details.@type = %s; want %s`, details[0].(map[string]interface{})["@type"], spec.details)
+			}
+		}
 	}
 }