G'day AnomalousMonk,

"The naming convention for SomeModule.pm test code is SomeModule.t. This is not enforced in any way, but it's what everyone expects."

I have never encountered that convention — where have you seen it? I certainly wouldn't expect it; I've mostly seen test files starting with numbers and are all lowercase (e.g. nn-name.t).

A t/ directory I'd create for an OO module might look something like:

00-load.t         # test 'use'
01-instantiate.t  # test 'new()'
02-some_func.t    # test 'some_func()'
...               # and so on ...
[download]

And, as a real world example, here's part of the output of make test for a $work module I ran in the last hour:

t/00-load.t ............... ok
t/01-instantiate.t ........ ok
t/02-overload.t ........... ok
t/03-validation.t ......... ok
...
[download]

Just in case I was having a sudden, and unexpected, mental breakdown, I checked a few arbitrary, but well-known, CPAN modules' t/ directories:

As you can see, for the most part they all follow the same basic naming convention (i.e. number, name, .t). There are a few exceptions (e.g. pod.t) but there are none that look like your SomeModule.t.