}
test_eval_ () {
- # We run this block with stderr redirected to avoid extra cruft
- # during a "-x" trace. Once in "set -x" mode, we cannot prevent
+ # If "-x" tracing is in effect, then we want to avoid polluting stderr
+ # with non-test commands. But once in "set -x" mode, we cannot prevent
# the shell from printing the "set +x" to turn it off (nor the saving
# of $? before that). But we can make sure that the output goes to
# /dev/null.
#
- # The test itself is run with stderr put back to &4 (so either to
- # /dev/null, or to the original stderr if --verbose was used).
+ # There are a few subtleties here:
+ #
+ # - we have to redirect descriptor 4 in addition to 2, to cover
+ # BASH_XTRACEFD
+ #
+ # - the actual eval has to come before the redirection block (since
+ # it needs to see descriptor 4 to set up its stderr)
+ #
+ # - likewise, any error message we print must be outside the block to
+ # access descriptor 4
+ #
+ # - checking $? has to come immediately after the eval, but it must
+ # be _inside_ the block to avoid polluting the "set -x" output
+ #
+
+ test_eval_inner_ "$@" </dev/null >&3 2>&4
{
- test_eval_inner_ "$@" </dev/null >&3 2>&4
test_eval_ret_=$?
if want_trace
then
set +x
- if test "$test_eval_ret_" != 0
- then
- say_color error >&4 "error: last command exited with \$?=$test_eval_ret_"
- fi
fi
- } 2>/dev/null
+ } 2>/dev/null 4>&2
+
+ if test "$test_eval_ret_" != 0 && want_trace
+ then
+ say_color error >&4 "error: last command exited with \$?=$test_eval_ret_"
+ fi
return $test_eval_ret_
}