Course of Raku / Advanced / Testing and documentation 🆕 / Testing 🆕

The Test module

Bring in the testing tools with use Test. The most basic check is ok, which passes when its condition is true. Each check takes an optional description:

use Test;

ok 1 == 1, 'one equals one';
ok 2 > 1,  'two is greater';

done-testing;

Running this prints, in the standard test format known as TAP:

ok 1 - one equals one
ok 2 - two is greater
1..2

Each passing check is reported as ok with its number and description; a failing one would be not ok. The final 1..2 is the plan, stating how many tests ran. The done-testing call at the end emits that plan automatically.

When you expect a specific value, is is clearer than ok, because it reports both the expected and the actual value on failure:

use Test;

is 2 + 2, 4, 'addition works';

done-testing;

This prints ok 1 - addition works. To see that reporting in action, give is a wrong expectation:

use Test;

is 2 + 2, 5, 'addition works';

done-testing;

Now the check fails, and the output explains exactly how:

not ok 1 - addition works
# Failed test 'addition works'
# at test.raku line 3
# expected: '5'
#      got: '4'
1..1
# You failed 1 test of 1

The not ok line marks the failure, and the diagnostic lines beneath it show what was expected against what actually turned up — which is why is is more helpful than a bare ok when a specific value matters.

ok, is, and done-testing are already enough to write a useful test file; the next topic adds the other comparisons.

Course navigation

← Testing 🆕   |   Quiz — Testing →

💪 Or jump directly to the exercises in this section.