On 2010-05-05 14:24:37 -0400, bearophile <[email protected]> said:
My post about unit test features contains other things worth discussing
about. This was just the first point :-)
Indeed.
I agree it'd be handy to have named unit tests. I see two reasons to
use named unit tests:
1. to print a list of all the tests as they run
2. to print a list of the tests that fails
Currently the output of a unittest is to print the first assertion that
fails. I think that's a good default, but if you add a name to your
unit test it can give you more context when it fails. Here's a way to
do it with the current syntax:
unittest {
scope (failure) writeln("Calculate pi using method X: FAIL");
auto result = methodX();
assert(result == 3.1416);
}
If the test fails, you'll get this output:
Calculate pi using method X: FAIL
file.d(5): assertion failure pi == 3.1416
which is a noticeable improvement because you don't have to go and look
at the file to know what this test is about.
If the test pass, it'll will output nothing. Whether we want to output
a line for every test, I'm not sure. D encourages small unit tests
scattered all around the place, and I'd be worried that being too
verbose when the tests are run would discourage people from running the
tests in the first place. On the other hand, it's useful, especially
when a test hangs, takes too long, or crashes the program, to be able
to see the list of all the tests as they run.
So what I would suggest is two things. A way to attach a name to a unit
test, like this:
unittest "Calculate pi using method x" {
...
}
This is better than scope (failure) because the test runner is now in
charge of deciding what to do with each test. I'd suggest that the
runtime print the name of a test when it fails:
Calculate pi using method X: FAIL
file.d(5): assertion failure pi == 3.1416
If the environment variable D_VERBOSE_UNITTEST is set when the program
is run, the runtime could print the name of each test as it executes
the test, followed by "PASS" upon successful completion or "FAIL" on
failure:
Calculate e using method X: PASS
Calculate pi using method X: FAIL
file.d(5): assertion failure pi == 3.1416
The environment variable makes sure that no one is bothered by a long
list of tests unless they explicitly ask for it. When you want to see
which tests are run and get a general feel of the time they take.
Any other use for named unit tests?
--
Michel Fortin
[email protected]
http://michelf.com/
