docstr: Relate a field of empty parents to empty children
docstr_tok: ["Relate","a","field","of","empty","parents","to","empty","children"]
code: def test_02_01_relate_zeros(self):
      """Relate a field of empty parents to empty children"""
      labels = numpy.zeros((10, 10), int)
      workspace, module = self.make_workspace(labels, labels)
      module.wants_per_parent_means.value = False
      module.run(workspace)
      m = workspace.measurements
      parents_of = m.get_current_measurement(
          CHILD_OBJECTS, "Parent_%s" % PARENT_OBJECTS
      )
      self.assertEqual(numpy.product(parents_of.shape), 0)
      child_count = m.get_current_measurement(
          PARENT_OBJECTS, "Children_%s_Count" % CHILD_OBJECTS
      )
      self.assertEqual(numpy.product(child_count.shape), 0)
      self.features_and_columns_match(workspace)
  
imports: import numpy
  import unittest
  import cellprofiler_core.image
  import cellprofiler_core.measurement
  import cellprofiler_core.module
  from cellprofiler_core.constants.measurement import C_PARENT, GROUP_NUMBER, GROUP_INDEX, COLTYPE_FLOAT, COLTYPE_INTEGER, M_LOCATION_CENTER_X, M_LOCATION_CENTER_Y, FF_PARENT
  import cellprofiler.modules.relateobjects
  import cellprofiler_core.object
  import cellprofiler_core.pipeline
  import cellprofiler_core.preferences
  import cellprofiler_core.workspace
label_desc: Use image node_id 3 for calling the TestRelateObjects obj's underlying member method code with example usage: obj.test_02_01_relate_zeros() without return types