new_contents: from tmuxp import shell
  from tmuxp._compat import string_types
  
  
  def test_detect_best_shell():
      result = shell.detect_best_shell()
      assert isinstance(result, string_types)
  
  
  def test_shell_detect():
      assert isinstance(shell.has_bpython(), bool)
      assert isinstance(shell.has_ipython(), bool)
      assert isinstance(shell.has_ptpython(), bool)
      assert isinstance(shell.has_ptipython(), bool)
  
subject: Test detect_best_shell, shell detection