test_ssl.rb: Test respecting system default min.

[junaruga]

This PR is adding a test for the #710 to ensure system wide setting MinProtocol is respected.

The test logic is similar with the #710 (comment). On the MinProtocol = TLSv1.3, it is testing that the client should fail to connect to TLS 1.2 server, and should succeed to connect to TLS 1.3 server.

What do you think?

[rhenium]

In #849 I didn't bother adding a separate test for MinProtocol, but this does add improve coverage.

Not blocking this, but 100 lines total for testing it feels a bit excessive. Perhaps we should expose SSLContext#{min,max}_version? Normally we'd provide a matching getter for a setter method, and the reason we didn't was that SSL_CTX_get_{min,max}_proto_version() didn't exist at that time (added in OpenSSL 1.1.0g). Since we now require OpenSSL 1.1.1 or later, that's no longer an issue.

[junaruga]

In #849 I didn't bother adding a separate test for MinProtocol, but this does add improve coverage.

Not blocking this, but 100 lines total for testing it feels a bit excessive. Perhaps we should expose SSLContext#{min,max}_version? Normally we'd provide a matching getter for a setter method, and the reason we didn't was that SSL_CTX_get_{min,max}_proto_version() didn't exist at that time (added in OpenSSL 1.1.0g). Since we now require OpenSSL 1.1.1 or later, that's no longer an issue.

I wondered why there were no getter methods of the SSLContext#{min,max}_version. Yes, I think these getter methods are very useful.

[rhenium]

Looks good to me, thank you!

[junaruga]

Thank you for your review!