Setting this new QTEST_DUMP_GRAPH environment variable causes qos-test
to dump the created qos graph (all nodes and edges, along with their
current individual availability status) to stdout.

See API doc comment on function qos_dump_graph() for details.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
---
 tests/qtest/qos-test.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tests/qtest/qos-test.c b/tests/qtest/qos-test.c
index 8fdf87b183..db667e16da 100644
--- a/tests/qtest/qos-test.c
+++ b/tests/qtest/qos-test.c
@@ -322,6 +322,9 @@ int main(int argc, char **argv)
     qos_set_machines_devices_available();
 
     qos_graph_foreach_test_path(walk_path);
+    if (getenv("QTEST_DUMP_GRAPH") != NULL) {
+        qos_dump_graph();
+    }
     g_test_run();
     qtest_end();
     qos_graph_destroy();
-- 
2.20.1