code: def test_empty_data(self):
      ds = PandasDataSource(
          schema={"feature1": float, "feature2": float}
      )
      self.assertEqual(0, len(list(ds.train)))
  
file_path: pytext/pytext/data/test/pandas_data_source_test.py
imports: import unittest
  import pandas
  from pytext.config.component import ComponentType, create_component
  from pytext.data.sources import PandasDataSource
label_desc: Use image node_id 3 for calling the PandasDataSourceTest obj's underlying member method code with example usage: obj.test_empty_data() without return types