Tuesday, 1 March 2011

Test::Harness, or a lesson about wheels not to be reinvented

Let’s say you have your unit tests in place, using something not particularly esoteric as Test::More. Good.

Now you want something to give some color to your output, so green is Good, red is Bad and you have a quicker feedback.

Time ago I wrote a quick shell script to run all the unit tests, interpret the output (in TAP format), print on screen some color output and stop the tests if something fails.

The core was:
function check_test_result() {

result=`perl $1`;

echo "$result"

perl -e '{ my $input = join(" ", @ARGV); if ($input =~ /not ok/m) { exit 0; } exit 1; }' $result

if [ $? -eq 0 ]
echo -e "$red Not all tests passed. FAILURE$end"
exit -1
echo -e "$green All tests passed. SUCCESS$end"

This works as soon as the unit tests fail (printing ‘not ok…’), but doesn’t quite work if something else is wrong (and you see the typical “your test died just after…” at the end).

Rather than improving this script, I was looking for a low hanging fruit, and eventually the easiest way I've found is to use Test::Harness prove, which BTW has color output by default.

So instead of the above (which needs also a few more lines to get the list of .t files), I can just use:

$ prove -v t/*.t

I mentioned Test::Harness prove in this post too, where I was using the JUnit module to convert from TAP to JUnit format, and get some nice code coverage report on Hudson.

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