old_contents: import unittest
  
  from urllib3.poolmanager import ProxyManager
  
  
  class TestProxyManager(unittest.TestCase):
      def test_proxy_headers(self):
          p = ProxyManager('http://something:1234')
          url = 'http://pypi.python.org/test'
  
          # Verify default headers
          default_headers = {'Accept': '*/*',
                             'Host': 'pypi.python.org'}
          headers = p._set_proxy_headers(url)
  
          self.assertEqual(headers, default_headers)
  
          # Verify default headers don't overwrite provided headers
          provided_headers = {'Accept': 'application/json',
                              'custom': 'header',
                              'Host': 'test.python.org'}
          headers = p._set_proxy_headers(url, provided_headers)
  
          self.assertEqual(headers, provided_headers)
  
          # Verify proxy with nonstandard port
          provided_headers = {'Accept': 'application/json'}
          expected_headers = provided_headers.copy()
          expected_headers.update({'Host': 'pypi.python.org:8080'})
          url_with_port = 'http://pypi.python.org:8080/test'
          headers = p._set_proxy_headers(url_with_port, provided_headers)
  
          self.assertEqual(headers, expected_headers)
  
      def test_default_port(self):
          p = ProxyManager('http://something')
          self.assertEqual(p.proxy.port, 80)
          p = ProxyManager('https://something')
          self.assertEqual(p.proxy.port, 443)
  
  
  if __name__ == '__main__':
      unittest.main()
  
new_contents: import unittest
  
  from urllib3.poolmanager import ProxyManager
  
  
  class TestProxyManager(unittest.TestCase):
      def test_proxy_headers(self):
          p = ProxyManager('http://something:1234')
          url = 'http://pypi.python.org/test'
  
          # Verify default headers
          default_headers = {'Accept': '*/*',
                             'Host': 'pypi.python.org'}
          headers = p._set_proxy_headers(url)
  
          self.assertEqual(headers, default_headers)
  
          # Verify default headers don't overwrite provided headers
          provided_headers = {'Accept': 'application/json',
                              'custom': 'header',
                              'Host': 'test.python.org'}
          headers = p._set_proxy_headers(url, provided_headers)
  
          self.assertEqual(headers, provided_headers)
  
          # Verify proxy with nonstandard port
          provided_headers = {'Accept': 'application/json'}
          expected_headers = provided_headers.copy()
          expected_headers.update({'Host': 'pypi.python.org:8080'})
          url_with_port = 'http://pypi.python.org:8080/test'
          headers = p._set_proxy_headers(url_with_port, provided_headers)
  
          self.assertEqual(headers, expected_headers)
  
      def test_default_port(self):
          p = ProxyManager('http://something')
          self.assertEqual(p.proxy.port, 80)
          p = ProxyManager('https://something')
          self.assertEqual(p.proxy.port, 443)
  
      def test_invalid_scheme(self):
          self.assertRaises(AssertionError, ProxyManager, 'invalid://host/p')
          self.assertRaises(ValueError, ProxyManager, 'invalid://host/p')
  
  
  if __name__ == '__main__':
      unittest.main()
  
subject: test backwardscompatible errors