Before you can run any tests you need to build curl but also build the test suite and its associated tools and servers.
Most conveniently, you can just build and run them all by issuing make test
in the build directory root but if you want to work more on tests or perhaps
even debug one, you may want to jump into the tests directory and work from
within that. Build it all and run test 144 like this:
cd tests
make
./runtests.pl 144