new_contents: from netlib import encoding
  
  def test_identity():
      assert "string" == encoding.decode("identity", "string")
      assert "string" == encoding.encode("identity", "string")
      assert not encoding.encode("nonexistent", "string")
      assert None == encoding.decode("nonexistent encoding", "string")
  
  
  def test_gzip():
      assert "string" == encoding.decode(
          "gzip",
          encoding.encode(
              "gzip",
              "string"))
      assert None == encoding.decode("gzip", "bogus")
  
  
  def test_deflate():
      assert "string" == encoding.decode(
          "deflate",
          encoding.encode(
              "deflate",
              "string"))
      assert "string" == encoding.decode(
          "deflate",
          encoding.encode(
              "deflate",
              "string")[
              2:-
              4])
      assert None == encoding.decode("deflate", "bogus")
  
subject: move encoding tests from mitmproxy to netlib