Perform the CTest Update Step as a Dashboard Client.
ctest_update([SOURCE <source-dir>] [RETURN_VALUE <result-var>] [QUIET])
Update the source tree from version control and record results in Update.xml for submission with the ctest_submit() command.
The options are:
The update always follows the version control branch currently checked out in the source directory. See the CTest Update Step documentation for more information.