From type/Test

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multi sub pass($desc = '')

The pass function marks a test as passed. flunk marks a test as not passed. Both functions accept an optional test description.

pass "Actually, this test has passed";
flunk "But this one hasn't passed";

Since these subroutines do not provide indication of what value was received and what was expected, they should be used sparingly, such as when evaluating a complex test condition.