Implement file exists check for executable

[akaszynski]

In https://github.com/pyansys/pydpf-core/blob/7d0c59796baac823702e38dcc0dcb74098844af0/ansys/dpf/core/server.py#L509 we don't check if the dpf server executable actually exists prior to running it. This appears to be version dependent and leads to a not so helpful traceback:

>>> model = Model(r'c:\static.rst')

Traceback (most recent call last):

  File "<pyshell#11>", line 1, in <module>

    model = Model(r'c:\static.rst')

  File "C:\Users\<redacted-user>\AppData\Local\Programs\Python\Python39\lib\site-packages\ansys\dpf\core\model.py", line 49, in __init__

    server = dpf.core._global_server()

  File "C:\Users\<redacted-user>\AppData\Local\Programs\Python\Python39\lib\site-packages\ansys\dpf\core\server.py", line 62, in _global_server

    start_local_server()

  File "C:\Users\<redacted-user>\AppData\Local\Programs\Python\Python39\lib\site-packages\ansys\dpf\core\server.py", line 177, in start_local_server

    server = DpfServer(ansys_path, ip, port,as_global= as_global, load_operators = load_operators)

  File "C:\Users\<redacted-user>\AppData\Local\Programs\Python\Python39\lib\site-packages\ansys\dpf\core\server.py", line 281, in __init__

    launch_dpf(ansys_path, ip, port)

  File "C:\Users\<redacted-user>\AppData\Local\Programs\Python\Python39\lib\site-packages\ansys\dpf\core\server.py", line 473, in launch_dpf

    process = subprocess.Popen(run_cmd,

  File "C:\Users\<redacted-user>\AppData\Local\Programs\Python\Python39\lib\subprocess.py", line 951, in __init__

    self._execute_child(args, executable, preexec_fn, close_fds,

  File "C:\Users\<redacted-user>\AppData\Local\Programs\Python\Python39\lib\subprocess.py", line 1420, in _execute_child

    hp, ht, pid, tid = _winapi.CreateProcess(executable, args,

FileNotFoundError: [WinError 2] The system cannot find the file specified

Would be great to implement a version and/or file exists check.

[rlagha]

good point @akaszynski yes, we should do this

[cbellot000]

@akaszynski we are checking if the directory exists:
https://github.com/pyansys/pydpf-core/blob/7d0c59796baac823702e38dcc0dcb74098844af0/ansys/dpf/core/server.py#L488-L509
Does that seem good to you?

[cbellot000]

@akaszynski, any update?