old_contents: import os
  import unittest
  
  from slack_sdk.proxy_env_variable_loader import load_http_proxy_from_env
  from tests.helpers import remove_os_env_temporarily, restore_os_env
  
  
  class TestProxyEnvVariableLoader(unittest.TestCase):
      def setUp(self):
          self.old_env = remove_os_env_temporarily()
  
      def tearDown(self):
          restore_os_env(self.old_env)
  
      def test_load_lower_case(self):
          os.environ["https_proxy"] = "http://localhost:9999"
          url = load_http_proxy_from_env()
          self.assertEqual(url, "http://localhost:9999")
  
      def test_load_upper_case(self):
          os.environ["HTTPS_PROXY"] = "http://localhost:9999"
          url = load_http_proxy_from_env()
          self.assertEqual(url, "http://localhost:9999")
  
new_contents: import os
  import unittest
  
  from slack_sdk.proxy_env_variable_loader import load_http_proxy_from_env
  from tests.helpers import remove_os_env_temporarily, restore_os_env
  
  
  class TestProxyEnvVariableLoader(unittest.TestCase):
      def setUp(self):
          self.old_env = remove_os_env_temporarily()
  
      def tearDown(self):
          os.environ.clear()
          restore_os_env(self.old_env)
  
      def test_load_lower_case(self):
          os.environ["https_proxy"] = "http://localhost:9999"
          url = load_http_proxy_from_env()
          self.assertEqual(url, "http://localhost:9999")
  
      def test_load_upper_case(self):
          os.environ["HTTPS_PROXY"] = "http://localhost:9999"
          url = load_http_proxy_from_env()
          self.assertEqual(url, "http://localhost:9999")
  
subject: Fix tests