old_contents: import io
  import os
  
  from tomlkit.toml_document import TOMLDocument
  from tomlkit.toml_file import TOMLFile
  
  
  def test_toml_file(example):
      original_content = example("example")
  
      toml_file = os.path.join(os.path.dirname(__file__), "examples", "example.toml")
      toml = TOMLFile(toml_file)
  
      content = toml.read()
      assert isinstance(content, TOMLDocument)
      assert content["owner"]["organization"] == "GitHub"
  
      toml.write(content)
  
      try:
          with io.open(toml_file, encoding="utf-8") as f:
              assert original_content == f.read()
      finally:
          with io.open(toml_file, "w", encoding="utf-8", newline="") as f:
              assert f.write(original_content)
  
new_contents: import io
  import os
  
  from tomlkit.toml_document import TOMLDocument
  from tomlkit.toml_file import TOMLFile
  
  
  def test_toml_file(example):
      original_content = example("example")
  
      toml_file = os.path.join(os.path.dirname(__file__), "examples", "example.toml")
      toml = TOMLFile(toml_file)
  
      content = toml.read()
      assert isinstance(content, TOMLDocument)
      assert content["owner"]["organization"] == "GitHub"
  
      toml.write(content)
  
      try:
          with io.open(toml_file, encoding="utf-8") as f:
              assert original_content == f.read()
      finally:
          with io.open(toml_file, "w", encoding="utf-8", newline="") as f:
              assert f.write(original_content)
  
  
  def test_keep_old_eol(tmpdir):
      toml_path = str(tmpdir / "pyproject.toml")
      with io.open(toml_path, "wb+") as f:
          f.write(b"a = 1\r\nb = 2\r\n")
  
      f = TOMLFile(toml_path)
      content = f.read()
      content["b"] = 3
      f.write(content)
  
      with io.open(toml_path, "rb") as f:
          assert f.read() == b"a = 1\r\nb = 3\r\n"
  
  
  def test_keep_old_eol_2(tmpdir):
      toml_path = str(tmpdir / "pyproject.toml")
      with io.open(toml_path, "wb+") as f:
          f.write(b"a = 1\nb = 2\n")
  
      f = TOMLFile(toml_path)
      content = f.read()
      content["b"] = 3
      f.write(content)
  
      with io.open(toml_path, "rb") as f:
          assert f.read() == b"a = 1\nb = 3\n"
  
  
  def test_mixed_eol(tmpdir):
      toml_path = str(tmpdir / "pyproject.toml")
      with io.open(toml_path, "wb+") as f:
          f.write(b"a = 1\r\nrb = 2\n")
  
      f = TOMLFile(toml_path)
      f.write(f.read())
  
      with io.open(toml_path, "rb") as f:
          assert f.read() == b"a = 1\r\nrb = 2\n"
  
subject: Add more tests