gm_ctflow

A helper application for cross-testcase test flows in Common Test

Description

When testing complex systems it often feels convenient to organize test sequences as a sequential group where a series of test cases perform a flow of operations. A challenge may arise when the results from one test case need to be reused by later cases - Common Test does cater for this through the save_config return.

However, occasionally, one also needs to have bespoke servers running for the duration of such a sequence, and this tends to lead to hacking a plain process with a custom protocol.

This application attempts to make that a bit more structured. In its initial version, there are two APIs:

• gm_ctflow_fun, where one can instantiate a stateful handler fun, which can be called by test cases as needed.
• gm_ctflow_worker, a gen_server where the server logic is given by a user-provided fun. The server is spawned under a simple_one_for_one supervisor.

The application gm_ctflow is intended to be started in init_per_suite/1 and stopped in end_per_suite/1, or in init_per_group/2 / end_per_group/2.

Some examples from test/gm_ctflow_SUITE.erl:

groups() ->
    [ {statefuns, [sequence], [ init_counter
                              , incr
                              , check1       %% state = 1
                              , incr
                              , check2       %% state = 2
                              , incr
                              , check3       %% state = 3
                              ]}
    , {workers, [sequence], [ init_counter
                            , init_worker
                            , append
                            , checkl1        %% [A0]
                            , append
                            , checkl2        %% [A0, A1]
                            , append
                            , checkl3        %% [A0, A1, A2]
                            ]}
    ].

Here, we interleave test cases with checks of the flow fun states. This test suite does nothing but exercize the flow funs, but normally, these funs would be used to e.g. spawn an endpoint needed for the tests, or thread some state through a test sequence.

The gm_ctflow application is started and stopped per-group here:

init_per_group(_Grp, Config) ->
    ok = application:start(gm_ctflow, permanent),
    Config.

end_per_group(_Grp, _Config) ->
    ok = application:stop(gm_ctflow),
    ok.

This resets the state and removes all helper processes for each group.

Build

$ rebar3 compile

Test

$ rebar ct