diff --git a/utility_test.go b/utility_test.go
new file mode 100644
index 0000000..abb1b63
--- /dev/null
+++ b/utility_test.go
@@ -0,0 +1,21 @@
+package exif
+
+import (
+    "testing"
+)
+
+func TestDumpBytesToString(t *testing.T) {
+    s := DumpBytesToString([]byte { 0x12, 0x34, 0x56 })
+
+    if s != "12 34 56" {
+        t.Fatalf("result not expected")
+    }
+}
+
+func TestDumpBytesClauseToString(t *testing.T) {
+    s := DumpBytesClauseToString([]byte { 0x12, 0x34, 0x56 })
+
+    if s != "0x12, 0x34, 0x56" {
+        t.Fatalf("result not expected")
+    }
+}