text: """Test case-sensitivity (PEP 235)."""
  from .. import util
  
  importlib = util.import_importlib('importlib')
  machinery = util.import_importlib('importlib.machinery')
  
  import os
  from test import support as test_support
  import unittest
  
  
  @util.case_insensitive_tests
  class CaseSensitivityTest(util.CASEOKTestBase):
  
      """PEP 235 dictates that on case-preserving, case-insensitive file systems
      that imports are case-sensitive unless the PYTHONCASEOK environment
      variable is set."""
  
      name = 'MoDuLe'
      assert name != name.lower()
  
      def finder(self, path):
          return self.machinery.FileFinder(path,
                                        (self.machinery.SourceFileLoader,
                                              self.machinery.SOURCE_SUFFIXES),
                                          (self.machinery.SourcelessFileLoader,
                                              self.machinery.BYTECODE_SUFFIXES))
  
      def sensitivity_test(self):
          """Look for a module with matching and non-matching sensitivity."""
          sensitive_pkg = 'sensitive.{0}'.format(self.name)
          insensitive_pkg = 'insensitive.{0}'.format(self.name.lower())
          context = util.create_modules(insensitive_pkg, sensitive_pkg)
          with context as mapping:
              sensitive_path = os.path.join(mapping['.root'], 'sensitive')
              insensitive_path = os.path.join(mapping['.root'], 'insensitive')
              sensitive_finder = self.finder(sensitive_path)
              insensitive_finder = self.finder(insensitive_path)
              return self.find(sensitive_finder), self.find(insensitive_finder)
  
      def test_sensitive(self):
          with test_support.EnvironmentVarGuard() as env:
              env.unset('PYTHONCASEOK')
              self.caseok_env_changed(should_exist=False)
              sensitive, insensitive = self.sensitivity_test()
              self.assertIsNotNone(sensitive)
              self.assertIn(self.name, sensitive.get_filename(self.name))
              self.assertIsNone(insensitive)
  
      def test_insensitive(self):
          with test_support.EnvironmentVarGuard() as env:
              env.set('PYTHONCASEOK', '1')
              self.caseok_env_changed(should_exist=True)
              sensitive, insensitive = self.sensitivity_test()
              self.assertIsNotNone(sensitive)
              self.assertIn(self.name, sensitive.get_filename(self.name))
              self.assertIsNotNone(insensitive)
              self.assertIn(self.name, insensitive.get_filename(self.name))
  
  
  class CaseSensitivityTestPEP302(CaseSensitivityTest):
      def find(self, finder):
          return finder.find_module(self.name)
  
  
  (Frozen_CaseSensitivityTestPEP302,
   Source_CaseSensitivityTestPEP302
   ) = util.test_both(CaseSensitivityTestPEP302, importlib=importlib,
                      machinery=machinery)
  
  
  class CaseSensitivityTestPEP451(CaseSensitivityTest):
      def find(self, finder):
          found = finder.find_spec(self.name)
          return found.loader if found is not None else found
  
  
  (Frozen_CaseSensitivityTestPEP451,
   Source_CaseSensitivityTestPEP451
   ) = util.test_both(CaseSensitivityTestPEP451, importlib=importlib,
                      machinery=machinery)
  
  
  if __name__ == '__main__':
      unittest.main()
  