test(util): add unit test for string util

pkg/util/strings_test.go

+package util
+
+import (
+	"testing"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestStringsUtil(t *testing.T) {
+	Convey("Falling back until none empty string", t, func() {
+		So(StringsFallback2("1", "2"), ShouldEqual, "1")
+		So(StringsFallback2("", "2"), ShouldEqual, "2")
+		So(StringsFallback3("", "", "3"), ShouldEqual, "3")
+	})
+}