perf test: Add shell test to validate JUnit XML reporting output

Add a shell test script (test_test_junit_output.sh) to execute perf test
with the -j/--junit option and validate that the generated test report
complies perfectly with standard XML formatting using Python's
ElementTree XML parser.

Assisted-by: Gemini-CLI:Google Gemini 3
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/shell/test_test_junit_output.sh

@@ -0,0 +1,63 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# perf test junit XML output validation
+
+set -e
+
+err=0
+
+shelldir=$(dirname "$0")
+# shellcheck source=lib/setup_python.sh
+. "${shelldir}"/lib/setup_python.sh
+
+result=$(mktemp /tmp/__perf_test.output.xml.XXXXX)
+
+cleanup()
+{
+	rm -f "${result}"
+	trap - exit term int
+}
+
+trap_cleanup()
+{
+	echo "Unexpected signal in ${FUNCNAME[1]}"
+	cleanup
+	exit 1
+}
+trap trap_cleanup exit term int
+
+test_junit_output()
+{
+	echo "Testing perf test JUnit XML output command"
+	perf test -v -j"$result" util || true
+	if [ -s "$result" ] ; then
+		echo "perf test JUnit XML output command [SUCCESS]"
+	else
+		echo "perf test JUnit XML output command [FAILED]"
+		err=1
+	fi
+}
+
+validate_xml_format()
+{
+	echo "Validating perf test converted JUnit XML file"
+	if [ -f "$result" ] ; then
+		if $PYTHON -c \
+		    "import xml.etree.ElementTree as ET; ET.parse('$result')" \
+		    >/dev/null 2>&1 ; then
+			echo "The file contains valid XML format [SUCCESS]"
+		else
+			echo "The file does not contain valid XML format [FAILED]"
+			err=1
+		fi
+	else
+		echo "File not found [FAILED]"
+		err=1
+	fi
+}
+
+test_junit_output
+validate_xml_format
+
+cleanup
+exit ${err}