refactor

varn/varn_test.go

@@ -0,0 +1,118 @@
+package varn_test
+
+import (
+	"bytes"
+	"encoding/hex"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"git.intruders.space/public/opentimestamps/varn"
+)
+
+// Helper functions for decoding (to verify encoding)
+func readVarUint(t *testing.T, data []byte) (uint64, int) {
+	t.Helper()
+	require.NotZero(t, data, "empty buffer")
+
+	if data[0] == 0 {
+		return 0, 1
+	}
+
+	var value uint64
+	var bytesRead int
+
+	for i, b := range data {
+		bytesRead = i + 1
+		value |= uint64(b&0x7F) << uint(7*i)
+		if b&0x80 == 0 {
+			break
+		}
+		require.Less(t, i, 9, "varint too long") // 9 is max bytes needed for uint64
+	}
+
+	return value, bytesRead
+}
+
+func readVarBytes(t *testing.T, data []byte) ([]byte, int) {
+	t.Helper()
+	length, bytesRead := readVarUint(t, data)
+
+	require.GreaterOrEqual(t, uint64(len(data)-bytesRead), length, "buffer too short")
+
+	end := bytesRead + int(length)
+	return data[bytesRead:end], end
+}
+
+func TestAppendVarUint(t *testing.T) {
+	tests := []struct {
+		name     string
+		value    uint64
+		expected string // hex representation of expected bytes
+	}{
+		{"zero", 0, "00"},
+		{"small value", 42, "2a"},
+		{"value below 128", 127, "7f"},
+		{"value requiring 2 bytes", 128, "8001"},
+		{"medium value", 300, "ac02"},
+		{"large value", 1234567890, "d285d8cc04"}, // Updated from "d2a6e58e07" to correct encoding
+		{"max uint64", 18446744073709551615, "ffffffffffffffffff01"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var buf []byte
+			result := varn.AppendVarUint(buf, tt.value)
+
+			// Check encoding
+			expected, err := hex.DecodeString(tt.expected)
+			assert.NoError(t, err)
+			assert.Equal(t, expected, result)
+
+			// Verify by decoding
+			decoded, _ := readVarUint(t, result)
+			assert.Equal(t, tt.value, decoded)
+		})
+	}
+}
+
+func TestAppendVarBytes(t *testing.T) {
+	tests := []struct {
+		name  string
+		value []byte
+	}{
+		{"empty", []byte{}},
+		{"small", []byte{0x01, 0x02, 0x03}},
+		{"medium", bytes.Repeat([]byte{0xAA}, 127)},
+		{"large", bytes.Repeat([]byte{0xBB}, 256)},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var buf []byte
+			result := varn.AppendVarBytes(buf, tt.value)
+
+			// Verify by decoding
+			decoded, _ := readVarBytes(t, result)
+			assert.Equal(t, tt.value, decoded)
+
+			// Check that length is properly encoded
+			lenEncoded, _ := readVarUint(t, result)
+			assert.Equal(t, uint64(len(tt.value)), lenEncoded)
+		})
+	}
+}
+
+func TestAppendingToExistingBuffer(t *testing.T) {
+	existing := []byte{0xFF, 0xFF}
+
+	// Test AppendVarUint
+	result := varn.AppendVarUint(existing, 42)
+	assert.Equal(t, []byte{0xFF, 0xFF, 0x2A}, result)
+
+	// Test AppendVarBytes
+	data := []byte{0x01, 0x02, 0x03}
+	result = varn.AppendVarBytes(existing, data)
+	assert.Equal(t, []byte{0xFF, 0xFF, 0x03, 0x01, 0x02, 0x03}, result)
+}