code: def testRegistry_ActiveContexts(self):
      reg = dsl_context_registry.get()
  
      self.assertEqual(reg.active_contexts, [])
      with _FakeContextManager() as c1:
          self.assertEqual(reg.active_contexts, [c1])
          with _FakeContextManager() as c2:
              self.assertEqual(reg.active_contexts, [c1, c2])
              with _FakeContextManager() as c3:
                  self.assertEqual(reg.active_contexts, [c1, c2, c3])
          with _FakeContextManager() as c4:
              self.assertEqual(reg.active_contexts, [c1, c4])
  
imports: from typing import Dict, Any
  import tensorflow
  from tfx.dsl.components.base import base_node
  from tfx.dsl.context_managers import dsl_context
  from tfx.dsl.context_managers import dsl_context_manager
  from tfx.dsl.context_managers import dsl_context_registry
  from tfx.utils import test_case_utils
label_desc: Use image node_id 5 for calling the ContextManagerTest obj's underlying member method code with example usage: obj.testRegistry_ActiveContexts() without return types