[ruby-core:117388] [Ruby master Bug#20403] TestResolvDNS#test_query_ipv4_address_truncated_tcp_fallback can flake if TCP port is in use

["kjtsanaktsidis (KJ Tsanaktsidis) via ruby-core" <ruby-core@ml.ruby-lang.org>]

Issue #20403 has been reported by kjtsanaktsidis (KJ Tsanaktsidis).

----------------------------------------
Bug #20403: TestResolvDNS#test_query_ipv4_address_truncated_tcp_fallback can flake if TCP port is in use
https://bugs.ruby-lang.org/issues/20403

* Author: kjtsanaktsidis (KJ Tsanaktsidis)
* Status: Open
* Assignee: kjtsanaktsidis (KJ Tsanaktsidis)
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
----------------------------------------
The test TestResolvDNS#test_query_ipv4_address_truncated_tcp_fallback wants to make a TCP and UDP DNS server on the same port. It achieves this by binding to a random UDP port (with `:0`), and then trying to bind to that TCP port. However, just because the UDP port was free, does not mean the TCP port was, so this can fail.

This leads to test failures like this one: https://github.com/ruby/ruby/actions/runs/8497267556/job/23275642160

```
     1) Error:
  TestResolvDNS#test_query_ipv4_address_truncated_tcp_fallback:
  Errno::EACCES: Permission denied - bind(2) for "127.0.0.1" port 49701
      D:/a/ruby/ruby/src/test/resolv/test_dns.rb:48:in 'TCPServer#initialize'
      D:/a/ruby/ruby/src/test/resolv/test_dns.rb:48:in 'IO.new'
      D:/a/ruby/ruby/src/test/resolv/test_dns.rb:48:in 'TestResolvDNS#with_tcp'
      D:/a/ruby/ruby/src/test/resolv/test_dns.rb:181:in 'block in TestResolvDNS#test_query_ipv4_address_truncated_tcp_fallback'
      D:/a/ruby/ruby/src/test/resolv/test_dns.rb:61:in 'TestResolvDNS#with_udp'
      D:/a/ruby/ruby/src/test/resolv/test_dns.rb:179:in 'TestResolvDNS#test_query_ipv4_address_truncated_tcp_fallback'
  
  Finished tests in 401.425882s, 64.4851 tests/s, 15534.2649 assertions/s.
  25886 tests, 6235856 assertions, 0 failures, 1 errors, 502 skips
```

(note - it's EACCESS, not EADDRINUSE, because of this issue on Windows, I think: https://stackoverflow.com/questions/48478869/cannot-bind-to-some-ports-due-to-permission-denied)



-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/