fstest: add fs.ErrorCantShareDirectories for backends which can only share files

fs/fs.go

@@ -68,6 +68,7 @@ var (
 	ErrorDirectoryNotEmpty           = errors.New("directory not empty")
 	ErrorImmutableModified           = errors.New("immutable file modified")
 	ErrorPermissionDenied            = errors.New("permission denied")
+	ErrorCantShareDirectories        = errors.New("this backend can't share directories with link")
 )
 
 // RegInfo provides information about a filesystem

fstest/fstests/fstests.go

@@ -1410,6 +1410,9 @@ func Run(t *testing.T, opt *Opt) {
 				// sharing directory for the first time
 				path := path.Dir(file2.Path)
 				link3, err := doPublicLink(context.Background(), path)
+				if err != nil && errors.Cause(err) == fs.ErrorCantShareDirectories {
+					t.Log("skipping directory tests as not supported on this backend")
+				} else {
 					require.NoError(t, err)
 					require.NotEqual(t, "", link3, "Link should not be empty")
 
@@ -1431,6 +1434,7 @@ func Run(t *testing.T, opt *Opt) {
 					link4, err := subRemote.Features().PublicLink(context.Background(), "")
 					require.NoError(t, err, "Sharing root in a sub-remote should work")
 					require.NotEqual(t, "", link4, "Link should not be empty")
+				}
 			})
 
 			// TestSetTier tests SetTier and GetTier functionality