DBIx::Admin::DSNManager manages a file of DSNs, for both testing and production.

The INI-style format was selected, rather than, say, using an SQLite database,
so that casual users could edit the file without needing to know SQL and without
having to install the command line program sqlite3.

Each DSN is normally for something requiring manual preparation, such as
creating the database named in the DSN.

In the case of SQLite, etc, where manual intervention is not required, you can
still put the DSN in dsn.ini.

One major use of this module is to avoid environment variable overload, since it
is common to test Perl modules by setting the env vars $DBI_DSN, $DBI_USER and
$DBI_PASS.

But then the problem becomes: What do you do when you want to run tests against
a set of databases servers? Some modules define sets of env vars, one set per
database server, with awkward and hard-to-guess names. This is messy and
obscure.

DBIx::Admin::DSNManager is a solution to this problem.