[ovs-dev] [PATCH] ovs-macros: An option to suspend test execution on error

[Vasu Dasari]

Origins for this patch are captured at
https://mail.openvswitch.org/pipermail/ovs-discuss/2019-June/048923.html.

Summarizing here, when a test fails, it would be good to pause test execution
and let the developer poke around the system to see current status of system.

As part of this patch, made a small tweaks to ovs-macros.at, so that when test
suite fails, ovs_on_exit() function will be called. And in this function, a check
is made to see if an environment variable to OVS_PAUSE_TEST is set. If it is
set, then test suite is paused and will continue to wait for user input
Ctrl-D. Meanwhile user can poke around the system to see why test case has
failed. Once done with investigation, user can press ctrl-d to cleanup the
test suite.

For example, to re-run test case 139:

export OVS_PAUSE_TEST=1
cd tests/system-userspace-testsuite.dir/139
sudo -E ./run

When error occurs, above command would display something like this:
=====================================================
Set environment variable to use various ovs utilities
export OVS_RUNDIR=/opt/vdasari/Developer/ovs/_build-gcc/tests/system-userspace-testsuite.dir/139
Press ctrl-d to continue:

=====================================================
And from another window, one can execute ovs-xxx commands like:
export OVS_RUNDIR=/opt/vdasari/Developer/ovs/_build-gcc/tests/system-userspace-testsuite.dir/139
$ ovs-ofctl dump-ports br0
.
.

Signed-off-by: Vasu Dasari <vdasari at gmail.com>
---
 tests/ovs-macros.at | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/tests/ovs-macros.at b/tests/ovs-macros.at
index 10593429d..57617a410 100644
--- a/tests/ovs-macros.at
+++ b/tests/ovs-macros.at
@@ -35,11 +35,36 @@ m4_divert_push([PREPARE_TESTS])
 # directory.
 ovs_init() {
     ovs_base=`pwd`
-    trap '. "$ovs_base/cleanup"' 0
+    trap ovs_on_exit 0
     : > cleanup
     ovs_setenv
 }
 
+# Catch testsuite error condition and cleanup test environment by tearing down
+# all interfaces and processes spawned.
+# User has an option to leave the test environment in error state so that system
+# can be poked around to get more information. User can enable this option by setting
+# environment variable OVS_PAUSE_TEST=1. User needs to press CTRL-D to resume the
+# cleanup operation.
+ovs_pause() {
+    echo "====================================================="
+    echo "Set environment variable to use various ovs utilities"
+    echo "export OVS_RUNDIR=$ovs_base"
+    echo "Press ctrl-d to continue:"
+    while read -s -n 1 key; do
+        printf -v keycode "%d" "'$key"
+        [ $keycode -ne 4 ] || break
+    done
+}
+
+ovs_on_exit () {
+    if [ ! -z "${OVS_PAUSE_TEST}" ]; then
+        trap '' INT
+        ovs_pause
+    fi
+    . "$ovs_base/cleanup"
+}
+
 # With no parameter or an empty parameter, sets the OVS_*DIR
 # environment variables to point to $ovs_base, the base directory in
 # which the test is running.
-- 
2.17.2 (Apple Git-113)