@VisibleForTesting
  void checkRemoteFilenameField( String remoteFilenameFieldName, SFTPPutData data )
    throws KettleStepException {
    remoteFilenameFieldName = environmentSubstitute( remoteFilenameFieldName );
    if ( !Utils.isEmpty( remoteFilenameFieldName ) ) {
      data.indexOfRemoteFilename = getInputRowMeta().indexOfValue( remoteFilenameFieldName );
      if ( data.indexOfRemoteFilename == -1 ) {
        // remote file name field is set, but was not found
        throw new KettleStepException( BaseMessages.getString(
          PKG, "SFTPPut.Error.CanNotFindField", remoteFilenameFieldName ) );
      }
    }
  }
@Test
  public void checkRemoteFilenameField_FieldNameIsBlank() throws Exception {
    SFTPPutData data = new SFTPPutData();
    step.checkRemoteFilenameField( "", data );
    assertEquals( -1, data.indexOfSourceFileFieldName );
  }