Addressing issue with non-deterministic test as tailers are set based…

… on the TailerMD, which is a map. The order a map is returned is non-deterministic.

runtime/handler_test.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"reflect"
+	"sort"
 	"testing"
 
 	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
@@ -542,7 +543,7 @@ func TestOutgoingTrailerMatcher(t *testing.T) {
 			headers: http.Header{
 				"Transfer-Encoding": []string{"chunked"},
 				"Content-Type":      []string{"application/json"},
-				"Trailer":           []string{"Grpc-Trailer-Foo", "Grpc-Trailer-Baz"},
+				"Trailer":           []string{"Grpc-Trailer-Baz", "Grpc-Trailer-Foo"},
 			},
 			trailer: http.Header{
 				"Grpc-Trailer-Foo": []string{"bar"},
@@ -607,7 +608,7 @@ func TestOutgoingTrailerMatcher(t *testing.T) {
 			headers: http.Header{
 				"Transfer-Encoding": []string{"chunked"},
 				"Content-Type":      []string{"application/json"},
-				"Trailer":           []string{"Grpc-Trailer-Foo", "Grpc-Trailer-Baz"},
+				"Trailer":           []string{"Grpc-Trailer-Baz", "Grpc-Trailer-Foo"},
 				"Etag":              []string{"\"41bf5d28a47f59b2a649e44f2607b0ea\""},
 			},
 			trailer: http.Header{
@@ -679,6 +680,9 @@ func TestOutgoingTrailerMatcher(t *testing.T) {
 				t.Fatalf("StatusCode %d want %d", w.StatusCode, http.StatusOK)
 			}
 
+			// Sort to the trailer headers to ensure the test is deterministic
+			sort.Strings(w.Header["Trailer"])
+
 			if !reflect.DeepEqual(w.Header, tc.headers) {
 				t.Fatalf("Header %v want %v", w.Header, tc.headers)
 			}