Implement formatting requests and parsing pieces

message/message_test.go

@@ -7,6 +7,128 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func TestFormatRequest(t *testing.T) {
+	msg := FormatRequest(4, 567, 4321)
+	expected := &Message{
+		ID: MsgRequest,
+		Payload: []byte{
+			0x00, 0x00, 0x00, 0x04, // Index
+			0x00, 0x00, 0x02, 0x37, // Begin
+			0x00, 0x00, 0x10, 0xe1, // Length
+		},
+	}
+	assert.Equal(t, expected, msg)
+}
+
+func TestParsePiece(t *testing.T) {
+	tests := map[string]struct {
+		inputIndex int
+		inputBuf   []byte
+		inputMsg   *Message
+		outputN    int
+		outputBuf  []byte
+		fails      bool
+	}{
+		"parse valid piece": {
+			inputIndex: 4,
+			inputBuf:   make([]byte, 10),
+			inputMsg: &Message{
+				ID: MsgPiece,
+				Payload: []byte{
+					0x00, 0x00, 0x00, 0x04, // Index
+					0x00, 0x00, 0x00, 0x02, // Begin
+					0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff, // Block
+				},
+			},
+			outputBuf: []byte{0x00, 0x00, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff, 0x00, 0x00},
+			outputN:   6,
+			fails:     false,
+		},
+		"wrong message type": {
+			inputIndex: 4,
+			inputBuf:   make([]byte, 10),
+			inputMsg: &Message{
+				ID:      MsgChoke,
+				Payload: []byte{},
+			},
+			outputBuf: make([]byte, 10),
+			outputN:   0,
+			fails:     true,
+		},
+		"payload too short": {
+			inputIndex: 4,
+			inputBuf:   make([]byte, 10),
+			inputMsg: &Message{
+				ID: MsgPiece,
+				Payload: []byte{
+					0x00, 0x00, 0x00, 0x04, // Index
+					0x00, 0x00, 0x00, // Malformed offset
+				},
+			},
+			outputBuf: make([]byte, 10),
+			outputN:   0,
+			fails:     true,
+		},
+		"wrong index": {
+			inputIndex: 4,
+			inputBuf:   make([]byte, 10),
+			inputMsg: &Message{
+				ID: MsgPiece,
+				Payload: []byte{
+					0x00, 0x00, 0x00, 0x06, // Index is 6, not 4
+					0x00, 0x00, 0x00, 0x02, // Begin
+					0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff, // Block
+				},
+			},
+			outputBuf: make([]byte, 10),
+			outputN:   0,
+			fails:     true,
+		},
+		"offset too high": {
+			inputIndex: 4,
+			inputBuf:   make([]byte, 10),
+			inputMsg: &Message{
+				ID: MsgPiece,
+				Payload: []byte{
+					0x00, 0x00, 0x00, 0x04, // Index is 6, not 4
+					0x00, 0x00, 0x00, 0x0c, // Begin is 12 > 10
+					0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff, // Block
+				},
+			},
+			outputBuf: make([]byte, 10),
+			outputN:   0,
+			fails:     true,
+		},
+		"offset ok but payload too long": {
+			inputIndex: 4,
+			inputBuf:   make([]byte, 10),
+			inputMsg: &Message{
+				ID: MsgPiece,
+				Payload: []byte{
+					0x00, 0x00, 0x00, 0x04, // Index is 6, not 4
+					0x00, 0x00, 0x00, 0x02, // Begin is ok
+					// Block is 10 long but begin=2; too long for input buffer
+					0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff, 0x0a, 0x0b, 0x0c, 0x0d,
+				},
+			},
+			outputBuf: make([]byte, 10),
+			outputN:   0,
+			fails:     true,
+		},
+	}
+
+	for _, test := range tests {
+		n, err := ParsePiece(test.inputIndex, test.inputBuf, test.inputMsg)
+		if test.fails {
+			assert.NotNil(t, err)
+		} else {
+			assert.Nil(t, err)
+		}
+		assert.Equal(t, test.outputBuf, test.inputBuf)
+		assert.Equal(t, test.outputN, n)
+	}
+}
+
 func TestMessageSerialize(t *testing.T) {
 	tests := map[string]struct {
 		input  *Message