# `Stampede.Scenario`
[🔗](https://github.com/mandar1045/stampede/blob/v0.2.0/lib/stampede/scenario.ex#L1)

The behaviour of a load test.

Only `c:run/1` is required:

    defmodule MyApp.Load.Home do
      use Stampede.Scenario

      @impl true
      def options, do: [vus: 10, duration: [minute: 1]]

      @impl true
      def run(_vu) do
        {:ok, socket} = Stampede.Channels.connect("ws://localhost:4000/socket")
        {:ok, _reply} = Stampede.Channels.join(socket, "home")
        Process.sleep(500)
      end
    end

`use Stampede.Scenario` declares the behaviour and nothing else.

# `options`
*optional* 

```elixir
@callback options() :: keyword()
```

Returns the default options of the scenario. See `Stampede.run/2`.

# `run`

```elixir
@callback run(vu :: Stampede.VU.t()) :: term()
```

Runs one iteration of a VU.

Stampede calls it again as soon as it returns, until the VU is stopped.
Sockets opened with `Stampede.Channels.connect/2` during an iteration are
closed when it returns, so a VU that should stay connected for the whole
test must keep `run/1` from returning, for example with a loop.

If `run/1` raises, throws or exits, the error is counted under
`"iteration.errors"` and the VU waits 100ms before its next iteration, so a
failing scenario does not spin.

# `setup`
*optional* 

```elixir
@callback setup(opts :: keyword()) :: term()
```

Runs once before the first VU starts, in the process that called
`Stampede.run/2`.

It receives the options of the run, and what it returns is given to every
VU as `vu.data`. Use it for work that should not be repeated, such as
creating accounts or signing tokens.

---

*Consult [api-reference.md](api-reference.md) for complete listing*