status: Remove IsSuccessful and ErrToStatus functions

Signed-off-by: Evgenii Baidakov <evgenii@nspcc.io>

client/common.go

@@ -199,10 +199,10 @@ func (x *contextCall) processResponse() bool {
 	// get result status
 	st := apistatus.FromStatusV2(x.resp.GetMetaHeader().GetStatus())
 
-	successfulStatus := apistatus.IsSuccessful(st)
-	x.err = apistatus.ErrFromStatus(st)
+	var errorExists bool
+	x.err, errorExists = st.(error)
 
-	return successfulStatus
+	return !errorExists
 }
 
 // processResponse verifies response signature.

client/status/status.go

@@ -27,18 +27,3 @@ func ErrFromStatus(st Status) error {
 
 	return nil
 }
-
-// ErrToStatus converts the error instance to Status instance.
-//
-// Note: direct assignment may not be compatibility-safe.
-func ErrToStatus(err error) Status {
-	return err
-}
-
-// IsSuccessful checks if status is successful.
-//
-// Note: direct cast may not be compatibility-safe.
-func IsSuccessful(st Status) bool {
-	_, ok := st.(error)
-	return !ok
-}

client/status/status_test.go

@@ -1,35 +0,0 @@
-package apistatus_test
-
-import (
-	"errors"
-	"testing"
-
-	apistatus "github.com/nspcc-dev/neofs-sdk-go/client/status"
-	"github.com/stretchr/testify/require"
-)
-
-func TestErrors(t *testing.T) {
-	t.Run("error source", func(t *testing.T) {
-		err := errors.New("some error")
-
-		st := apistatus.ErrToStatus(err)
-
-		success := apistatus.IsSuccessful(st)
-		require.False(t, success)
-
-		res := apistatus.ErrFromStatus(st)
-
-		require.ErrorIs(t, res, err)
-	})
-
-	t.Run("non-error source", func(t *testing.T) {
-		var st apistatus.Status = "any non-error type"
-
-		success := apistatus.IsSuccessful(st)
-		require.True(t, success)
-
-		res := apistatus.ErrFromStatus(st)
-
-		require.Nil(t, res)
-	})
-}

client/status/v2.go

@@ -126,12 +126,13 @@ func ToStatusV2(st Status) *status.Status {
 		return v.ToStatusV2()
 	}
 
-	if IsSuccessful(st) {
+	err, isErrorExists := st.(error)
+	if !isErrorExists {
 		return newStatusV2WithLocalCode(status.OK, status.GlobalizeSuccess)
 	}
 
 	internalErrorStatus := newStatusV2WithLocalCode(status.Internal, status.GlobalizeCommonFail)
-	internalErrorStatus.SetMessage(st.(error).Error()) // type cast never panics because IsSuccessful() checks cast
+	internalErrorStatus.SetMessage(err.Error())
 
 	return internalErrorStatus
 }