[2.3][Process] Make process tests more accurate on exception messages

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

I need exception message to be checked more accurately in my upcoming PR about windows.
I decided to make a separated PR as the other one will probably take some time before being merged