diff --git a/checksum_test.go b/checksum_test.go
new file mode 100644
index 0000000..ecadf32
--- /dev/null
+++ b/checksum_test.go
@@ -0,0 +1,14 @@
+
+package ts
+
+import (
+	"testing"
+)
+
+func TestChecksum(t *testing.T) {
+	b := []byte("hello world")
+	b = append(b, []byte{0xbb,0x08,0xec,0x87}...)
+	crc := updateIeeeCrc32(0xffffffff, b)
+	t.Logf("%x", crc)
+}
+
diff --git a/writer_test.go b/writer_test.go
new file mode 100644
index 0000000..3439b87
--- /dev/null
+++ b/writer_test.go
@@ -0,0 +1,19 @@
+
+package ts
+
+import (
+	"testing"
+	"encoding/hex"
+	"bytes"
+)
+
+func TestWriteTSHeader(t *testing.T) {
+	bw := &bytes.Buffer{}
+	w := &TSWriter{
+		W: bw,
+		PCR: 0x12345678,
+	}
+	w.Write([]byte{'h','e','l','o'}[:], false)
+	t.Logf("\n%s", hex.Dump(bw.Bytes()))
+}
+