title: How do you use CTEST_CUSTOM_PRE_TEST?
body: <p>I've searched all the docs but can't seem to find a single example of using CTEST_CUSTOM_PRE_TEST.</p>
  
  <p>Basically I need to start and run some commands on the server before the test runs. So I need to add a few pre-test steps. What's the syntax of CTEST_CUSTOM_PRE_TEST?</p>
  
  <p>CTEST_CUSTOM_PRE_TEST( ??? what to put here ??? )
  ADD_TEST(MyTest MyTestCommand)</p>