Structuring unit tests

[Kostis Sagonas]

Thomas Lindgren gave the following advice:
 >
 > --- Joel Reymont <joelr1@REDACTED> wrote:
 > > exporting all the tested functions or placing a
 > > -compile([export_all]) at the top of the module to be tested. 
 > 
 > You can also do that with a command line option:
 > 
 > % erlc +export_all mymod.erl
 > 
 > That means you can make it a flag in the makefile,
 > which often is useful.

Please do not follow these paths, and please do not give such "advice".

Do the following instead: If you have a module m that exports
functions f1, ..., fn and contains test functions t1, ..., tm, which
are internal (i.e., module-local) and return 'ok' when passing the
test, export a *single* function test/0 which looks as follows:

test() ->
  ok = t1(...),
  ok = t2(...),
  ...
  ok = tm(...).

If you absolutely positively need to test t1, ..., tm individually,
then export a function test/1 which looks as:

test(t1) ->
  ok = t1(...);
test(t2) ->
  ok = t2(...);
...
test(tm) ->
  ok = tm(...).

There is very little reason to use 'export_all' for this task.

Best,
Kostis