diff --git a/helper.go b/helper.go
index 4666ca5..ead5b88 100644
--- a/helper.go
+++ b/helper.go
@@ -63,13 +63,15 @@ func resolveAddress(addr []string) (fullAddr string) {
 		return ip + ":8080"
 	case 1:
 		var port string
+
+		// "IP:PORT"
 		if strings.IndexByte(addr[0], ':') != -1 {
 			ss := strings.SplitN(addr[0], ":", 2)
 			if ss[0] != "" {
 				return addr[0]
 			}
 			port = ss[1]
-		} else {
+		} else { // Only port
 			port = addr[0]
 		}
 
@@ -131,8 +133,11 @@ func debugPrint(f string, v ...interface{}) {
 
 // from gin framework
 func parseAccept(acceptHeader string) []string {
-	parts := strings.Split(acceptHeader, ",")
+	if acceptHeader == "" {
+		return []string{}
+	}
 
+	parts := strings.Split(acceptHeader, ",")
 	if len(parts) == 0 {
 		return []string{}
 	}
diff --git a/helper_test.go b/helper_test.go
new file mode 100644
index 0000000..8cacaec
--- /dev/null
+++ b/helper_test.go
@@ -0,0 +1,37 @@
+package rux
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestHelper(t *testing.T) {
+
+	// resolveAddress
+	addr := resolveAddress(nil)
+	assert.Equal(t, "0.0.0.0:8080", addr)
+
+	addr = resolveAddress([]string{"9090"})
+	assert.Equal(t, "0.0.0.0:9090", addr)
+
+	addr = resolveAddress([]string{"127.0.0.1:9090"})
+	assert.Equal(t, "127.0.0.1:9090", addr)
+
+	// use ENV
+
+	// debugPrintError
+	debugPrintError(errors.New("error msg"))
+
+	// parseAccept
+	ss := parseAccept("")
+	assert.Len(t, ss, 0)
+
+	ss = parseAccept(",")
+	assert.Len(t, ss, 0)
+
+	ss = parseAccept("application/json")
+	assert.Len(t, ss, 1)
+	assert.Equal(t, []string{"application/json"}, ss)
+}