Merge pull request #644 from nspcc-dev/fix/array_reverse

util: always copy argument in ArrayReverse

pkg/util/array.go

@@ -2,10 +2,6 @@ package util
 
 // ArrayReverse returns a reversed version of the given byte slice.
 func ArrayReverse(b []byte) []byte {
-	// Protect from big.Ints that have 1 len bytes.
-	if len(b) < 2 {
-		return b
-	}
 	dest := make([]byte, len(b))
 	for i, j := 0, len(b)-1; i <= j; i, j = i+1, j-1 {
 		dest[i], dest[j] = b[j], b[i]

pkg/util/array_test.go

@@ -6,24 +6,40 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestArrayEvenReverse(t *testing.T) {
-	arr := []byte{0x01, 0x02, 0x03, 0x04}
-	have := ArrayReverse(arr)
-	want := []byte{0x04, 0x03, 0x02, 0x01}
-	require.Equal(t, want, have)
+var testCases = []struct {
+	arr []byte
+	rev []byte
+}{
+	{
+		arr: []byte{},
+		rev: []byte{},
+	},
+	{
+		arr: []byte{0x01},
+		rev: []byte{0x01},
+	},
+	{
+		arr: []byte{0x01, 0x02, 0x03, 0x04},
+		rev: []byte{0x04, 0x03, 0x02, 0x01},
+	},
+	{
+		arr: []byte{0x01, 0x02, 0x03, 0x04, 0x05},
+		rev: []byte{0x05, 0x04, 0x03, 0x02, 0x01},
+	},
 }
 
-func TestArrayOddReverse(t *testing.T) {
-	arr := []byte{0x01, 0x02, 0x03, 0x04, 0x05}
-	have := ArrayReverse(arr)
-	want := []byte{0x05, 0x04, 0x03, 0x02, 0x01}
-	require.Equal(t, want, have)
-}
+func TestArrayReverse(t *testing.T) {
+	for _, tc := range testCases {
+		arg := make([]byte, len(tc.arr))
+		copy(arg, tc.arr)
 
-// This tests a bug that occurred with arrays of size 1
-func TestArrayReverseLen2(t *testing.T) {
-	arr := []byte{0x01}
-	have := ArrayReverse(arr)
-	want := []byte{0x01}
-	require.Equal(t, want, have)
+		have := ArrayReverse(arg)
+		require.Equal(t, tc.rev, have)
+
+		// test that argument was copied
+		for i := range have {
+			have[i] = ^have[i]
+		}
+		require.Equal(t, tc.arr, arg)
+	}
 }