postgresql/src/test/modules/test_integerset

test_integerset contains unit tests for testing the integer set implementation
in src/backend/lib/integerset.c.

The tests verify the correctness of the implementation, but they can also be
used as a micro-benchmark.  If you set the 'intset_test_stats' flag in
test_integerset.c, the tests will print extra information about execution time
and memory usage.