[ovs-dev] [PATCH v2] 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 ENTER 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
.
.

To be able to pause while performing `make check`, one can do:
$ OVS_PAUSE_TEST=1 make check TESTSUITEFLAGS='-v'

Signed-off-by: Vasu Dasari <vdasari at gmail.com>
Reviewed-by: Ben Pfaff <blp at ovn.org>
Reviewed-by: Aaron Conole <aconole at redhat.com>
---
v0 -> v1:
Discussion at: https://mail.openvswitch.org/pipermail/ovs-dev/2019-July/360589.html
1. Incorporated review commanets from Ben.
2. Changed topics/testing.rst to document this trick
3. Made this trick work via "make check" as well, by issuing command: "OVS_PAUSE_TEST=1
make check TESTSUITEFLAGS='-v'"

v1 -> v2:
Discussion at: https://mail.openvswitch.org/pipermail/ovs-dev/2019-July/360705.html
1. Added a subsection, "Debugging unit tests"
2. Renamed $as_echo to just echo. AS_ECHO is not suported in autoconf 2.69.11. And, we are not gainin
g anything from AS_ECHO in this code, just using echo.

---
 Documentation/topics/testing.rst | 31 +++++++++++++++++++++++++++++++
 tests/ovs-macros.at              | 24 +++++++++++++++++++++++-
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/Documentation/topics/testing.rst b/Documentation/topics/testing.rst
index a8892e1c1..73077042c 100644
--- a/Documentation/topics/testing.rst
+++ b/Documentation/topics/testing.rst
@@ -81,6 +81,37 @@ To see a complete list of test options, run::
 The results of a testing run are reported in ``tests/testsuite.log``. Report
 report test failures as bugs and include the ``testsuite.log`` in your report.
 
+Debugging unit tests
+++++++++++++++++++++
+
+To initiate debugging from artifacts generated from `make check` run, use
+following instructions. 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=<dir>/ovs/_build-gcc/tests/system-userspace-testsuite.dir/139
+   Press ENTER 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
+   .
+   .
+
+Once done with investigation, press ENTER to perform cleanup operation.
+
+To be able to pause on error while performing `make check`, one can do::
+
+  $ OVS_PAUSE_TEST=1 make check TESTSUITEFLAGS='-v'
+
+and then follow similar on screen instructions
+
 .. note::
   Sometimes a few tests may fail on some runs but not others. This is usually a
   bug in the testsuite, not a bug in Open vSwitch itself. If you find that a
diff --git a/tests/ovs-macros.at b/tests/ovs-macros.at
index 10593429d..b6add7fda 100644
--- a/tests/ovs-macros.at
+++ b/tests/ovs-macros.at
@@ -35,11 +35,33 @@ 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 following environment variable to use various ovs utilities"
+    echo "export OVS_RUNDIR=$ovs_base"
+    echo "Press ENTER to continue: "
+    read
+}
+
+ovs_on_exit () {
+    if [ ! -z "${OVS_PAUSE_TEST}" ] && [ -z $at_verbose ]; then
+        trap '' INT
+        ovs_pause
+    fi
+    . "$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)