old_contents: """Run tests on Executor."""
  import unittest
  import Executor
  
  
  class TestExecutor(unittest.TestCase):
      """Test cases for the Executor."""
  
      def test_syntax_tree(self):
          """Test the syntax_tree method."""
          syntax_tree = Executor.syntax_tree()
          self.assertTrue(syntax_tree is not None)
          self.assertEqual(syntax_tree.type, Executor.TYPES[Executor._SEQUENCE])
  
  if __name__ == "__main__":
      unittest.main()
  
new_contents: """Test package for Executor.py."""
  import unittest
  import Executor
  
  
  class TestExecutor(unittest.TestCase):
      """Test cases for the Executor."""
  
      def test_syntax_tree(self):
          """Test the syntax_tree method."""
          syntax_tree = Executor.syntax_tree()
          self.assertTrue(syntax_tree is not None)
          self.assertEqual(syntax_tree.type, Executor.TYPES[Executor._SEQUENCE])
  
      def test_namespace(self):
          """Test the Namespace class."""
          ns = Executor.Namespace(None)
          self.assertEqual(ns.parent, None)
          self.assertEqual(ns.find_identifier("identifier"), None)
          self.assertEqual(ns.find_operator("operator"), None)
          # store example operator
          ns.put_identifier("a", 0)
          ns.put_operator("a", 1)
          self.assertEqual(ns.find_identifier("a"), 0)
          self.assertEqual(ns.find_operator("a"), 1)
          # test upper namspace
          sub = Executor.Namespace(ns)
          self.assertEqual(sub.find_identifier("a"), 0)
          self.assertEqual(sub.find_operator("a"), 1)
          # check independence
          sub.put_identifier("missing", -1)
          sub.put_operator("missing", -2)
          self.assertEqual(ns.find_identifier("missing"), None)
          self.assertEqual(ns.find_operator("missing"), None)
  
      def test_default_namespace(self):
          """Test the default_namespace method."""
          ns = Executor.default_namespace()
          self.assertEqual(ns.parent, None)
          self.assertEqual(ns.find_identifier(""), None)
          self.assertEqual(ns.find_operator(""), None)
  
      def test_run_in_substitution(self):
          """Test the run_in_substitution method."""
          access_node_type = {
              "name": "Test",
              "execution": lambda n, c: c["local"].put_identifier("x", 0),
          }
          context = Executor.default_context()
          access_node = Executor.Node(access_node_type, None)
          Executor.run_in_substitution(access_node, context)
          self.assertEqual(context["local"].find_identifier("x"), None)
  
          value_node_type = {
              "name": "Test",
              "execution": lambda n, c: Executor.store_none(),
          }
          context = Executor.default_context()
          value_node = Executor.Node(value_node_type, None)
          value_result = Executor.run_in_substitution(value_node, context)
          self.assertEqual(value_result, Executor.store_none())
  
      def test_default_context(self):
          """Test the default_context method."""
          pass
  
      def test_store_none(self):
          """Test the store_none method."""
          a = Executor.store_none()
          b = Executor.store_none()
          self.assertEqual(a["type"], Executor.DATA_NONE)
          self.assertEqual(a["value"], None)
          self.assertEqual(a, b)
  
      def test_store_value(self):
          """Test the store_value method."""
  
      def test_sequence_node(self):
          """Test the sequence node."""
          sequence = Executor.Node(Executor.TYPES[Executor._SEQUENCE], None)
          context = Executor.default_context()
          predicted_result = Executor.store_none()
          self.assertEqual(sequence.eval(context), predicted_result)
  
      def test_branch_node(self):
          """Test the branch node."""
          pass
  
      def test_loop_node(self):
          """Test the loop node."""
          pass
  
      def test_return_node(self):
          """Test the return node."""
          pass
  
      def test_break_node(self):
          """Test the break node."""
          pass
  
      def test_continue_node(self):
          """Test the continue node."""
          pass
  
      def test_function_node(self):
          """Test the function node."""
          pass
  
      def test_operator_node(self):
          """Test the operator node."""
          pass
  
      def test_identifier_node(self):
          """Test the identifier node."""
          pass
  
      def test_literal_node(self):
          """Test the literal node."""
          pass
  
  if __name__ == "__main__":
      unittest.main()
  
subject: Update unit tests for Executor.py