# FnLoadTester
[](https://hex.pm/packages/fn_load_tester) [](https://hexdocs.pm/fn_load_tester/) [](https://travis-ci.org/mendrugory/fn_load_tester)
`FnLoadTester` is a helper tool to execute load tests against your functions, especially your `GenServer`s, and calculate statistics of the test.
## Installation
If [available in Hex](https://hex.pm/docs/publish), the package can be installed
by adding `fn_load_tester` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:fn_load_tester, "~> 0.1.0", only: :dev}
]
end
```
## Stats
`FnLoadTester` brings some basic statistics but it also gives you the possibility of adding your own statistics.
To Build a new `Stats` it is only necessary to `use FnLoadTester.Stats` and implement the callbacks:
* calculate(list): the input is a list of times and the output has to be a number.
* units(): The outpus has to be an atom which indicates the unit of the output of calculate:
* :nanosecond
* :microsecond
* :millisecond
* :second
* title(): The output will be a string with the _Title_ of the statistics.
```elixir
defmodule MyMaximum do
use FnLoadTester.Stats
def calculate(data), do: Enum.max(data)
def units(), do: :nanosecond
def title(), do: "My Maximum"
end
```
In order to have more information, check the module `FnLoadTester.Stats`
## Execution
In order to execute the load test you only have to specify the number of parallel clients that will execute the given function and the number of requests per client. The fourth argument (optional) is the statistics that will be calculated.
```elixir
iex> FnLoadTester.request(1, 100, fn -> MyGenServer.execute() end)
Maximum: 104610 ns
Minimum: 20123 ns
Average: 26940 ns
Percentile50: 21877 ns
Percentile90: 36460 ns
Percentile95: 50784 ns
Percentile99: 104610 ns
:ok
```
```elixir
iex> FnLoadTester.request(1, 100, fn -> MyGenServer.execute() end, [FnLoadTester.Stats.Maximum, FnLoadTester.Stats.Minimum])
Maximum: 104610 ns
Minimum: 20123 ns
:ok
```
## Test
```bash
mix test
```
