test(pdo_firebird): Fix the dummy server running on localhost to IPv4

[KentarouTakeda]

This is related to #16113.

In the pdo_firebird test, a dummy server was created on localhost using stream_socket_server() to test for error responses that do not normally occur.

stream_socket_get_name() was used to generate the name of the dummy server, but this function seems to return the IPv6 address ::1 even in host environments where IPv6 is not available. As a result, in certain environments it was not possible to connect to the dummy server, and the test failed.

This problem is solved by creating a server on 127.0.0.1 and fixing it to IPv4, rather than creating it on localhost and leaving the choice of IPv6 or IPv4 to stream_socket_get_name().

[KentarouTakeda]

Note: The issue fixed by this pull request potentially existed before #16113.

When I created #12677 in the past, I encountered the exact same test failure in the docker environment I personally use. I left it as it was because it didn't reproduce in CI, but after seeing #16113, I realized the cause.

I'm submitting screenshots of before and after the fix for your reference.

• Before fix - fail
  

• After fix - pass
  

[nielsdos]

Thanks a lot! This looks good to me but I'll wait for Saki to confirm.
I filed an issue for stream_socket_get_name(): #16117

[SakiTakamachi]

LGTM thanks!