Do not set content-type on empty content for compress middleware

Author: lammel

middleware/compress.go

@@ -80,7 +80,7 @@ func GzipWithConfig(config GzipConfig) echo.MiddlewareFunc {
 				w.Reset(rw)
 				grw := &gzipResponseWriter{Writer: w, ResponseWriter: rw}
 				defer func() {
-					if !grw.wroteBody {
+					if !grw.wroteBody || res.Size == 0 {
 						if res.Header().Get(echo.HeaderContentEncoding) == gzipScheme {
 							res.Header().Del(echo.HeaderContentEncoding)
 						}

middleware/compress_test.go

@@ -114,7 +114,7 @@ func TestGzipEmpty(t *testing.T) {
 		return c.String(http.StatusOK, "")
 	})
 	if assert.NoError(t, h(c)) {
-		assert.Equal(t, gzipScheme, rec.Header().Get(echo.HeaderContentEncoding))
+		assert.Empty(t, rec.Header().Get(echo.HeaderContentEncoding))
 		assert.Equal(t, "text/plain; charset=UTF-8", rec.Header().Get(echo.HeaderContentType))
 		r, err := gzip.NewReader(rec.Body)
 		if assert.NoError(t, err) {