[LTP] [RFC PATCH] test.sh: add SHOULD_PASS, SHOULD_FAIL functions

[Stanislav Kholmanskikh]

Sometimes we need to execute a command and call tst_resm TPASS/TFAIL
based on the command's exit status.

The existing ROD() function can make 99% of the job, we just
need to let it know how the command's exit code should be
interpreted. This patch does it and introduce a couple of new
functions to help with the described situation.

Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>
---
This is to help with situations like:

echo 1.0 > memory.limit_in_bytes 2> /dev/null
if [ $? -ne 0 ]; then
   tst_resm TPASS "return value is $?"
else
   tst_resm TFAIL "return value is 0"
fi

which could be transformed to:

SHOULD_FAIL echo 1.0 \> memory.limit_in_bytes


 testcases/lib/test.sh |   50 +++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/testcases/lib/test.sh b/testcases/lib/test.sh
index bd66109..ca2c00b 100644
--- a/testcases/lib/test.sh
+++ b/testcases/lib/test.sh
@@ -220,12 +220,17 @@ ROD_SILENT()
 	fi
 }
 
-ROD()
+ROD_DISPATCHER()
 {
+	local act
 	local cmd
 	local arg
 	local file
 	local flag
+	local ret
+
+	act="$1"
+	shift
 
 	for arg; do
 		file="${arg#\>}"
@@ -251,9 +256,46 @@ ROD()
 		$@
 	fi
 
-	if [ $? -ne 0 ]; then
-		tst_brkm TBROK "$@ failed"
-	fi
+	ret=$?
+
+	case "$act" in
+		0) # break on failure
+		if [ $ret -ne 0 ]; then
+			tst_brkm TBROK "$@ failed"
+		fi;;
+
+		1) # the command should pass
+		if [ $ret -eq 0 ]; then
+			tst_resm TPASS "$@ passed as expected"
+		else
+			tst_resm TFAIL "$@ failed unexpectedly"
+		fi;;
+
+		2) # the command should fail
+		if [ $ret -ne 0 ]; then
+			tst_resm TPASS "$@ failed as expected"
+		else
+			tst_resm TFAIL "$@ passed unexpectedly"
+		fi;;
+
+		*) tst_brkm TBROK "unknown action '$act'";;
+	esac
+}
+
+ROD()
+{
+	ROD_DISPATCHER 0 $@
+}
+
+SHOULD_PASS()
+{
+	ROD_DISPATCHER 1 $@
+}
+
+SHOULD_FAIL()
+{
+	# redirect stderr since we expect the command to fail
+	ROD_DISPATCHER 2 $@ 2> /dev/null
 }
 
 tst_acquire_device()
-- 
1.7.1