class_docstr: Tests of GraphSAGELinkGenerator class
docstr: The SampledBFS sampler, created inside the mapper, currently throws a ValueError when the num_samples list is empty.
  This might change in the future, so this test might have to be re-written.
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code: def test_no_samples(self, samples):
      """
      The SampledBFS sampler, created inside the mapper, currently throws a ValueError when the num_samples list is empty.
      This might change in the future, so this test might have to be re-written.
  
      """
      G = example_graph(feature_size=self.n_feat)
      data_size = G.number_of_edges()
      edge_labels = [0] * data_size
      in_samples, out_samples = samples
  
      mapper = DirectedGraphSAGELinkGenerator(
          G,
          batch_size=self.batch_size,
          in_samples=in_samples,
          out_samples=out_samples,
      ).flow(G.edges(), edge_labels)
  
      assert len(mapper) == 2
      with pytest.raises(ValueError):
          nf, nl = mapper[0]
  
imports: import numpy
  import networkx
  import pytest
  import random
  from stellargraph.mapper import *
  from stellargraph.core.graph import *
  from stellargraph.data.unsupervised_sampler import *
  from ..test_utils.graphs import example_graph, example_graph_random, example_hin_1, repeated_features, weighted_tree
  from ..None import test_utils
label_desc: Use image node_id 5 for calling the Test_DirectedGraphSAGELinkGenerator obj's underlying member method code with example usage: obj.test_no_samples(samples) without return types