text: import pytest
  import xarray
  from argopy.data_fetchers.proto import ArgoDataFetcherProto
  
  
  class Fetcher(ArgoDataFetcherProto):
  
      def to_xarray(self, *args, **kwargs):
          super(Fetcher, self).to_xarray(*args, **kwargs)
  
      def filter_variables(self, *args, **kwargs):
          super(Fetcher, self).filter_variables(*args, **kwargs)
  
      def filter_qc(self, *args, **kwargs):
          super(Fetcher, self).filter_qc(*args, **kwargs)
  
      def filter_data_mode(self, *args, **kwargs):
          super(Fetcher, self).filter_data_mode(*args, **kwargs)
  
  
  def test_abstracts():
      f = Fetcher()
      with pytest.raises(NotImplementedError):
          f.to_xarray()
      with pytest.raises(NotImplementedError):
          f.filter_variables(xarray.Dataset, str)
      with pytest.raises(NotImplementedError):
          f.filter_qc(xarray.Dataset)
      with pytest.raises(NotImplementedError):
          f.filter_data_mode(xarray.Dataset)
  