ruby - Why don't rails tests give me useful error messages? -

i'm pretty new rails, , i'm trying functional tests going on rails application, , of tests throwing errors. something's set wrong, don't know yet, trying figure out. testing output not helping me @ all. here's test output looks (somewhat truncated):

started  attachmentscontrollertest:      pass should index (0.29s)  readercontrollertest:      pass should catalog (0.09s)  should volume (0.01s)  ...  finished in 0.411071 seconds.  6 tests, 5 assertions, 0 failures, 1 errors, 0 skips rake aborted! 

this totally useless. okay, there's error in volume test. kind of error? where's being thrown? don't know, , won't tell me. way less useful if said "one or more of tests has failure and/or error". has stupid newbie question, how can meaningful information out of errors thrown?

assume know absolutely nothing testing built rails. because don't. can't find documentation on reading output, , "give me stack trace" command line argument gives me stack trace exit 1 uses tell os there failures, patently worthless.

edit: i'm using 1.9.3, if it's relevant, , i'm running tests rake test:functionals (since there no unit tests in there). also, neil asked rakefile, reads follows:

#!/usr/bin/env rake # add own tasks in files placed in lib/tasks ending in .rake, # example lib/tasks/capistrano.rake, , automatically available rake.  require file.expand_path('../config/application', __file__)  kidbooks::application.load_tasks 

and lib/tasks empty.