rtla/tests: Check rtla output with grep

Add argument to the check command in the test suite that takes a regular
expression that the output of rtla command is checked against. This
allows testing for specific information in rtla output in addition
to checking the return value.

Two minor improvements are included: running rtla with "eval" so that
arguments with spaces can be passed to it via shell quotations, and
the stdout of pushd and popd is suppressed to clean up the test output.

Cc: John Kacur <[email protected]>
Cc: Luis Goncalves <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Chang Yin <[email protected]>
Cc: Costa Shulyupin <[email protected]>
Cc: Crystal Wood <[email protected]>
Cc: Gabriele Monaco <[email protected]>
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: lenticularis39

tools/tracing/rtla/tests/engine.sh

@@ -11,7 +11,7 @@ test_begin() {
 reset_osnoise() {
 	# Reset osnoise options to default and remove any dangling instances created
 	# by improperly exited rtla runs.
-	pushd /sys/kernel/tracing || return 1
+	pushd /sys/kernel/tracing >/dev/null || return 1
 
 	# Remove dangling instances created by previous rtla run
 	echo 0 > tracing_thresh
@@ -35,11 +35,14 @@ reset_osnoise() {
 	echo 0 > stop_tracing_us
 	echo 1000 > timerlat_period_us
 
-	popd
+	popd >/dev/null
 }
 
 check() {
+	test_name=$0
+	tested_command=$1
 	expected_exitcode=${3:-0}
+	expected_output=$4
 	# Simple check: run rtla with given arguments and test exit code.
 	# If TEST_COUNT is set, run the test. Otherwise, just count.
 	ctr=$(($ctr + 1))
@@ -49,15 +52,25 @@ check() {
 		[ "$NO_RESET_OSNOISE" == 1 ] || reset_osnoise
 		# Run rtla; in case of failure, include its output as comment
 		# in the test results.
-		result=$(stdbuf -oL $TIMEOUT "$RTLA" $2 2>&1); exitcode=$?
-		if [ $exitcode -eq $expected_exitcode ]
+		result=$(eval stdbuf -oL $TIMEOUT "$RTLA" $2 2>&1); exitcode=$?
+		# Test if the results matches if requested
+		if [ -n "$expected_output" ]
+		then
+			grep -E "$expected_output" <<< "$result" > /dev/null; grep_result=$?
+		else
+			grep_result=0
+		fi
+
+		if [ $exitcode -eq $expected_exitcode ] && [ $grep_result -eq 0 ]
 		then
 			echo "ok $ctr - $1"
 		else
 			echo "not ok $ctr - $1"
 			# Add rtla output and exit code as comments in case of failure
 			echo "$result" | col -b | while read line; do echo "# $line"; done
 			printf "#\n# exit code %s\n" $exitcode
+			[ -n "$expected_output" ] && \
+				printf "# Output match failed: \"%s\"\n" "$expected_output"
 		fi
 	fi
 }