View Source Developing a scenario

Developing a scenario

A scenario specification is an Erlang or Elixir module that implements the amoc_scenario behaviour. It has to export two callback functions:

• init/0 - called only once per test run on every node, at the very beginning. It can be used for setting up initial (global) state: metrics, database connections, etc. It can return an ok or a tuple {ok, State} from which the State may be passed to every user.
• start/1 or start/2 - implements the actual scenario and is executed for each user, in the context of that user's process. The first argument is the given user's unique integer id. The second, which is optional, is the state, as returned from the init/0 function.

In addition to that, the scenario module can implement a terminate/0,1 callback; it has one optional argument – the scenario state, as returned from the init/0 function.

A typical scenario file will look like this:

-module(my_scenario).

-behaviour(amoc_scenario).

-export([init/0]).
-export([start/1]).

init() ->
    %% initialize some metrics
    ok.

start(Id) ->
    %% connect user
    %% fetch user's history
    %% send some messages
    %% wait a little bit
    %% send some messages again
    ok.

defmodule LoadTest do
  @behaviour :amoc_scenario

  def init do
    ## initialize some metrics
    :ok
  end

  def start(id) do
    ## connect user
    ## fetch user's history
    ## send some messages
    ## wait a little bit
    ## send some messages again
    :ok
  end

end

or, using the start/2 function:

-module(my_scenario).

-behaviour(amoc_scenario).

-export([init/0]).
-export([start/2]).

init() ->
    %% initialize some metrics
    Settings = get_settings(),
    {ok, Settings}.

start(Id, Settings) ->
    %% connect user using Settings
    %% fetch user's history
    %% send some messages
    %% wait a little bit
    %% send some messages again
    ok.

defmodule LoadTest do
  @behaviour :amoc_scenario

  def init do
    ## initialize some metrics
    settings = get_settings()
    {:ok, settings}
  end

  def start(id, settings) do
    ## connect user using Settings
    ## fetch user's history
    ## send some messages
    ## wait a little bit
    ## send some messages again
    :ok
  end

end

For developing XMPP scenarios, we recommend the esl/escalus library. If additional dependencies are required by your scenario, a rebar.config file can be created inside the scenario dir and deps from that file will be merged with Amoc's dependencies.

Coordinate users

See Amoc coordinator.

Throttle actions

See Amoc throttle.