Add checks for programs which are required for the test suite to run. All prerequisite programs are checked for existance, and if any are missing, a list of missing programs is printed, and the test suite is aborted. All programs currently used in the tests, except those in core-utils, are checked.

#!/bin/sh

hg init
echo a > a
hg add a
hg commit -m "test" -d "0 0"
hg history
hg tag -d "0 0" "bleah" 
hg history

echo foo >> .hgtags
hg tag -d "0 0" "bleah2" || echo "failed"