base58: add a test for a025b9c42d

As noted by @fyrchik in #579 comments.

pkg/encoding/base58/base58_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestCheckEncodeDecode(t *testing.T) {
@@ -30,3 +31,11 @@ func TestCheckDecodeFailures(t *testing.T) {
 	_, err = CheckDecode(badcsum)
 	assert.NotNil(t, err)
 }
+
+func TestBase58LeadingZeroes(t *testing.T) {
+	buf := []byte{0, 0, 0, 1}
+	b58 := CheckEncode(buf)
+	dec, err := CheckDecode(b58)
+	require.NoError(t, err)
+	require.Equal(t, buf, dec)
+}