text: """Tests for the asdl parser in Parser/asdl.py"""
  
  import importlib.machinery
  import importlib.util
  import os
  from os.path import dirname
  import sys
  import sysconfig
  import unittest
  
  
  # This test is only relevant for from-source builds of Python.
  if not sysconfig.is_python_build():
      raise unittest.SkipTest('test irrelevant for an installed Python')
  
  src_base = dirname(dirname(dirname(__file__)))
  parser_dir = os.path.join(src_base, 'Parser')
  
  
  class TestAsdlParser(unittest.TestCase):
      @classmethod
      def setUpClass(cls):
          # Loads the asdl module dynamically, since it's not in a real importable
          # package.
          # Parses Python.asdl into an ast.Module and run the check on it.
          # There's no need to do this for each test method, hence setUpClass.
          sys.path.insert(0, parser_dir)
          loader = importlib.machinery.SourceFileLoader(
                  'asdl', os.path.join(parser_dir, 'asdl.py'))
          spec = importlib.util.spec_from_loader('asdl', loader)
          module = importlib.util.module_from_spec(spec)
          loader.exec_module(module)
          cls.asdl = module
          cls.mod = cls.asdl.parse(os.path.join(parser_dir, 'Python.asdl'))
          cls.assertTrue(cls.asdl.check(cls.mod), 'Module validation failed')
  
      @classmethod
      def tearDownClass(cls):
          del sys.path[0]
  
      def setUp(self):
          # alias stuff from the class, for convenience
          self.asdl = TestAsdlParser.asdl
          self.mod = TestAsdlParser.mod
          self.types = self.mod.types
  
      def test_module(self):
          self.assertEqual(self.mod.name, 'Python')
          self.assertIn('stmt', self.types)
          self.assertIn('expr', self.types)
          self.assertIn('mod', self.types)
  
      def test_definitions(self):
          defs = self.mod.dfns
          self.assertIsInstance(defs[0], self.asdl.Type)
          self.assertIsInstance(defs[0].value, self.asdl.Sum)
  
          self.assertIsInstance(self.types['withitem'], self.asdl.Product)
          self.assertIsInstance(self.types['alias'], self.asdl.Product)
  
      def test_product(self):
          alias = self.types['alias']
          self.assertEqual(
              str(alias),
              'Product([Field(identifier, name), Field(identifier, asname, opt=True)])')
  
      def test_attributes(self):
          stmt = self.types['stmt']
          self.assertEqual(len(stmt.attributes), 4)
          self.assertEqual(repr(stmt.attributes[0]), 'Field(int, lineno)')
          self.assertEqual(repr(stmt.attributes[1]), 'Field(int, col_offset)')
          self.assertEqual(repr(stmt.attributes[2]), 'Field(int, end_lineno, opt=True)')
          self.assertEqual(repr(stmt.attributes[3]), 'Field(int, end_col_offset, opt=True)')
  
      def test_constructor_fields(self):
          ehandler = self.types['excepthandler']
          self.assertEqual(len(ehandler.types), 1)
          self.assertEqual(len(ehandler.attributes), 4)
  
          cons = ehandler.types[0]
          self.assertIsInstance(cons, self.asdl.Constructor)
          self.assertEqual(len(cons.fields), 3)
  
          f0 = cons.fields[0]
          self.assertEqual(f0.type, 'expr')
          self.assertEqual(f0.name, 'type')
          self.assertTrue(f0.opt)
  
          f1 = cons.fields[1]
          self.assertEqual(f1.type, 'identifier')
          self.assertEqual(f1.name, 'name')
          self.assertTrue(f1.opt)
  
          f2 = cons.fields[2]
          self.assertEqual(f2.type, 'stmt')
          self.assertEqual(f2.name, 'body')
          self.assertFalse(f2.opt)
          self.assertTrue(f2.seq)
  
      def test_visitor(self):
          class CustomVisitor(self.asdl.VisitorBase):
              def __init__(self):
                  super().__init__()
                  self.names_with_seq = []
  
              def visitModule(self, mod):
                  for dfn in mod.dfns:
                      self.visit(dfn)
  
              def visitType(self, type):
                  self.visit(type.value)
  
              def visitSum(self, sum):
                  for t in sum.types:
                      self.visit(t)
  
              def visitConstructor(self, cons):
                  for f in cons.fields:
                      if f.seq:
                          self.names_with_seq.append(cons.name)
  
          v = CustomVisitor()
          v.visit(self.types['mod'])
          self.assertEqual(v.names_with_seq,
                           ['Module', 'Module', 'Interactive', 'FunctionType'])
  
  
  if __name__ == '__main__':
      unittest.main()
  