diff --git a/swagger_test.go b/swagger_test.go
index dd75f74..337cc8e 100644
--- a/swagger_test.go
+++ b/swagger_test.go
@@ -5,7 +5,6 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
-	"sync"
 	"testing"
 
 	"github.com/gin-contrib/gzip"
@@ -23,17 +22,6 @@ func (s *mockedSwag) ReadDoc() string {
 }`
 }
 
-var (
-	once sync.Once
-	doc  = &mockedSwag{}
-)
-
-func regDoc() {
-	once.Do(func() {
-		swag.Register(swag.Name, doc)
-	})
-}
-
 func TestWrapHandler(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	router := gin.New()
@@ -44,8 +32,6 @@ func TestWrapHandler(t *testing.T) {
 }
 
 func TestWrapCustomHandler(t *testing.T) {
-	regDoc()
-	
 	gin.SetMode(gin.TestMode)
 	router := gin.New()
 
@@ -55,7 +41,10 @@ func TestWrapCustomHandler(t *testing.T) {
 	assert.Equal(t, http.StatusOK, w1.Code)
 	assert.Equal(t, w1.Header()["Content-Type"][0], "text/html; charset=utf-8")
 
-	assert.Equal(t, http.StatusOK, performRequest(http.MethodGet, "/doc.json", router).Code)
+	assert.Equal(t, http.StatusInternalServerError, performRequest(http.MethodGet, "/doc.json", router).Code)
+
+	doc := &mockedSwag{}
+	swag.Register(swag.Name, doc)
 
 	w2 := performRequest(http.MethodGet, "/doc.json", router)
 	assert.Equal(t, http.StatusOK, w2.Code)
@@ -86,8 +75,6 @@ func TestWrapCustomHandler(t *testing.T) {
 }
 
 func TestDisablingWrapHandler(t *testing.T) {
-	regDoc()
-
 	gin.SetMode(gin.TestMode)
 
 	router := gin.New()
@@ -129,8 +116,6 @@ func TestDisablingCustomWrapHandler(t *testing.T) {
 }
 
 func TestWithGzipMiddleware(t *testing.T) {
-	regDoc()
-
 	gin.SetMode(gin.TestMode)
 	router := gin.New()