add deprecated test case (#1176)

* add deprecated test case

* swap assert param

* remove

context_test.go

@@ -676,6 +676,7 @@ func TestContextRenderNoContentSecureJSON(t *testing.T) {
 func TestContextRenderHTML(t *testing.T) {
 	w := httptest.NewRecorder()
 	c, router := CreateTestContext(w)
+
 	templ := template.Must(template.New("t").Parse(`Hello {{.name}}`))
 	router.SetHTMLTemplate(templ)
 
@@ -686,6 +687,30 @@ func TestContextRenderHTML(t *testing.T) {
 	assert.Equal(t, "text/html; charset=utf-8", w.HeaderMap.Get("Content-Type"))
 }
 
+func TestContextRenderHTML2(t *testing.T) {
+	w := httptest.NewRecorder()
+	c, router := CreateTestContext(w)
+
+	// print debug warning log when Engine.trees > 0
+	router.addRoute("GET", "/", HandlersChain{func(_ *Context) {}})
+	assert.Len(t, router.trees, 1)
+
+	var b bytes.Buffer
+	setup(&b)
+	defer teardown()
+
+	templ := template.Must(template.New("t").Parse(`Hello {{.name}}`))
+	router.SetHTMLTemplate(templ)
+
+	assert.Equal(t, "[GIN-debug] [WARNING] Since SetHTMLTemplate() is NOT thread-safe. It should only be called\nat initialization. ie. before any route is registered or the router is listening in a socket:\n\n\trouter := gin.Default()\n\trouter.SetHTMLTemplate(template) // << good place\n\n", b.String())
+
+	c.HTML(201, "t", H{"name": "alexandernyquist"})
+
+	assert.Equal(t, 201, w.Code)
+	assert.Equal(t, "Hello alexandernyquist", w.Body.String())
+	assert.Equal(t, "text/html; charset=utf-8", w.HeaderMap.Get("Content-Type"))
+}
+
 // Tests that no HTML is rendered if code is 204
 func TestContextRenderNoContentHTML(t *testing.T) {
 	w := httptest.NewRecorder()