protocol/rtp: wrote TestCsrcCount

Wrote test TestCsrcCount to check behaviour of csrcCount is expected.

protocol/rtp/parse_test.go

@@ -40,3 +40,18 @@ func TestVersion(t *testing.T) {
 		t.Errorf("unexpected version for RTP packet. Got: %v\n Want: %v\n", got, expect)
 	}
 }
+
+// TestCsrcCount checks that we can correctly obtain the csrc count from an
+// RTP packet.
+func TestCsrcCount(t *testing.T) {
+	const ver, expect = 2, 2
+	pkt := (&Pkt{
+		V:    ver,
+		CC:   expect,
+		CSRC: make([][4]byte, expect),
+	}).Bytes(nil)
+	got := csrcCount(pkt)
+	if got != expect {
+		t.Errorf("unexpected csrc count for RTP packet. Got: %v\n Want: %v\n", got, expect)
+	}
+}