> Why do I, some random person installing this module, care if the tests pass now?
Because running those tests in your environment ensures that... that module can run in your environment.
By way of example, if a module requires a specific library installed to actually run, running its tests will ensure you catch the problem, and install it, so it can then actually run. Else you'd only find out at runtime that something's missing.
Note also that not all tests are the same, and (unfortunately!) not all modules' tests are the same, either: there's tests that ensure the module works "generally", and there's some author/development tests that on a _properly written_ module are only ran by the author/developer, and skip running when the modules are instead installed by mere users, for whom instead the "standard" "will this module work in this environment?" tests are the only one that get ran.
> I have horrible memories of the DBD::MySQL package failing to install because it ran tests that assumed localhost was running a MySQL server
I believe that got fixed, IIRC, as I've had no trouble installing that module (and running its tests at install time, natch). I said "fixed" as that seems like the sort of test that makes sense for the module's authors/developers to run, and not mere users of it.
Because running those tests in your environment ensures that... that module can run in your environment.
By way of example, if a module requires a specific library installed to actually run, running its tests will ensure you catch the problem, and install it, so it can then actually run. Else you'd only find out at runtime that something's missing.
Note also that not all tests are the same, and (unfortunately!) not all modules' tests are the same, either: there's tests that ensure the module works "generally", and there's some author/development tests that on a _properly written_ module are only ran by the author/developer, and skip running when the modules are instead installed by mere users, for whom instead the "standard" "will this module work in this environment?" tests are the only one that get ran.
> I have horrible memories of the DBD::MySQL package failing to install because it ran tests that assumed localhost was running a MySQL server
I believe that got fixed, IIRC, as I've had no trouble installing that module (and running its tests at install time, natch). I said "fixed" as that seems like the sort of test that makes sense for the module's authors/developers to run, and not mere users of it.