add tests for ACK frame parsing

ack_frame_test.go

@@ -8,6 +8,33 @@ import (
 )
 
 var _ = Describe("AckFrame", func() {
+	Context("when parsing", func() {
+		It("accepts sample frame", func() {
+			b := bytes.NewReader([]byte{0x40, 0xA4, 0x03, 0x23, 0x45, 0x01, 0x02, 0xFF, 0xEE, 0xDD, 0xCC})
+			frame, err := ParseAckFrame(b)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(frame.Entropy).To(Equal(byte(0xA4)))
+			Expect(frame.LargestObserved).To(Equal(uint64(0x03)))
+			Expect(frame.DelayTime).To(Equal(uint16(0x4523)))
+			Expect(b.Len()).To(Equal(0))
+		})
+
+		It("parses a frame with a 48 bit packet number", func() {
+			b := bytes.NewReader([]byte{0x4C, 0xA4, 0x37, 0x13, 0xAD, 0xFB, 0xCA, 0xDE, 0x23, 0x45, 0x01, 0x02, 0xFF, 0xEE, 0xDD, 0xCC})
+			frame, err := ParseAckFrame(b)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(frame.LargestObserved).To(Equal(uint64(0xDECAFBAD1337)))
+			Expect(b.Len()).To(Equal(0))
+		})
+
+		It("completely parses a frame with multiple timestamps", func() {
+			b := bytes.NewReader([]byte{0x40, 0xA4, 0x03, 0x23, 0x45, 0x03, 0x02, 0xFF, 0xEE, 0xDD, 0xCC, 0x12, 0x34, 0x56, 0x78, 0x90, 0xA0})
+			_, err := ParseAckFrame(b)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(b.Len()).To(Equal(0))
+		})
+	})
+
 	Context("when writing", func() {
 		It("writes simple frames", func() {
 			b := &bytes.Buffer{}