[erlang-questions] Automated testing of a distributed application

[Lukas Larsson]

Hello!

The ct_master module is not really meant to test distributed
applications, but rather to distribute your tests. It helps you when
you have 1000 tests to run, but can only finish 500 per day and you
need to run all of them each day.

When testing distributed application with common_test, I use the
ct_slave (or just even slave) module and configure slaves to be
started on node X and Y and then run test suites on node Z which
trigger test behavior either through rpc or SIP och whatever interface
you want to test. Serializing test calls and making sure that no test
cases interfere with each other I do in the testcase and suite as I
would with a non-distributed application.

Lukas

On Tue, Dec 20, 2011 at 1:56 AM, Garret Smith <garret.smith@REDACTED> wrote:
> I just finished setting up an automated test suite for my distributed
> application using the common_test "Large Scale Testing" support.  It was
> rough, but *almost* works.  It starts up 2 local nodes, starts my app on
> both nodes, runs a few test cases from my suite on node1, a second batch of
> cases on node2, then yet another batch of cases on node1.
>
> The test cases are designed to work by contacting the distributed app on
> node1, modifying it's state through the API, then contacting the app on
> node2 to verify that the state changes are reflected there, then repeating
> from the perspective of node2.
>
> sample test spec, invoked with ct_master:run/1
>
> {logdir, "../logs"}.
>
> {alias, testdir, "."}.
>
> {init, [n1, n2], {node_start, [{erl_flags, "-pa ../../ebin"},
> {monitor_master, true}]}}.
>
> {merge_tests, false}.
>
> {cases, n1, testdir, distributed_SUITE, [create_table, insert_1]}.
> {cases, n2, testdir, distributed_SUITE, [read_1, update_2]}.
> {cases, n1, testdir, distributed_SUITE, [read_2]}.
>
>
>
> Now that my basic setup using ct_master is working, I notice that sometimes
> the tests fail because I cannot depend on the batches being executed in
> sequence.  ct_master executes the test cases in parallel on the two nodes.
> I could continue down this path by adding synchronization somehow, but I
> feel that I am not really using ct_master in the way it was intended.
>
> Has anyone on the list had experience writing an automated test suite where
> the SUT is a single app running on a cluster of nodes?  Were you able to do
> this with common_test, or did you end up rolling your own framework?
>
> Thanks!
>
> -Garret Smith
>
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