Add some tests

* ntp timestamp conversion
* RTP Extension validation

Relates to #15

packet_test.go

@@ -82,6 +82,17 @@ func TestExtension(t *testing.T) {
 		t.Fatal("Unmarshal did not error on packet with invalid extension length")
 	}
 
+	p = &Packet{Header: Header{
+		Extension:        true,
+		ExtensionProfile: 3,
+		ExtensionPayload: []byte{0},
+	},
+		Payload: []byte{},
+	}
+	if _, err := p.Marshal(); err == nil {
+		t.Fatal("Marshal did not error on packet with invalid extension length")
+	}
+
 }
 
 func BenchmarkMarshal(b *testing.B) {

packetizer_test.go

@@ -0,0 +1,26 @@
+package rtp
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNtpConversion(t *testing.T) {
+	loc := time.FixedZone("UTC-5", -5*60*60)
+
+	tests := []struct {
+		t time.Time
+		n uint64
+	}{
+		{t: time.Date(1985, time.June, 23, 4, 0, 0, 0, loc), n: 0xa0c65b1000000000},
+		{t: time.Date(1999, time.December, 31, 23, 59, 59, 500000, loc), n: 0xbc18084f0020c49b},
+		{t: time.Date(2019, time.March, 27, 13, 39, 30, 8675309, loc), n: 0xe04641e202388b88},
+	}
+
+	for _, in := range tests {
+		out := toNtpTime(in.t)
+		assert.Equal(t, in.n, out)
+	}
+}