PROPOSAL: Allow passing ExUnit custom formatter options when configuring ExUnit

[Devon Estes]

I'm writing a custom formatter for ExUnit and there is some configuration I would like the user to be able to do. However, it would be much better for the configuration to be able to happen by passing arguments to the `init/1` callback so we don't need to rely on compile time application config for this. Right now, since all custom formatters are just passed the ExUnit configuration when they're started in `ex_unit/lib/ex_unit/event_manager.ex`, and the user can't control how these custom formatters are started, I don't see a way to do this.

My proposal is to make a small change to the ExUnit configuration for formatters. Instead of only allowing a list of module names representing the GenServer we're going to use as formatters, we can also accept a tuple that contains the module name of our GenServer as well as configuration for that formatter. For example:

ExUnit.configure(formatters: [ExUnit.CLIFormatter, {CustomFormatter, %{print_results: false, email_results: true, api_key: System.get_env("API_KEY")}}])

Since then these options would be passed to our CustomFormatter when it's started, it would be easy enough for me to pick them up by doing:

def init(opts) do

  {_, my_opts} = Enum.find(opts[:formatters], {nil, %{}}, fn

    {__MODULE__, _} -> true

    _ -> false

  end)

  {:ok, my_opts}

end

[José Valim]

I believe currently we pass all of the options given to configure. So you could do:

ExUnit.configure custom_formatter: %{print_results: ...}

Would this work? Is this acceptable?

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D

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[Devon Estes]

Yeah, that it would work since the options are just a keyword list. B I worry that because that behavior isn't documented it could be confusing to folks. That's why I was thinking there could be an official, documented way of passing these options to custom formatters.

Alternatively, we could just document that `ExUnit.configure/1` accepts the currently documented options, but can also accept any other options that might be needed as configuration for cases like this.

On Friday, August 17, 2018 at 1:14:45 PM UTC+2, José Valim wrote:

I believe currently we pass all of the options given to configure. So you could do:

ExUnit.configure custom_formatter: %{print_results: ...}

Would this work? Is this acceptable?

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D

On Fri, Aug 17, 2018 at 1:07 PM, Devon Estes <devon....@gmail.com> wrote:

I'm writing a custom formatter for ExUnit and there is some configuration I would like the user to be able to do. However, it would be much better for the configuration to be able to happen by passing arguments to the `init/1` callback so we don't need to rely on compile time application config for this. Right now, since all custom formatters are just passed the ExUnit configuration when they're started in `ex_unit/lib/ex_unit/event_manager.ex`, and the user can't control how these custom formatters are started, I don't see a way to do this.

My proposal is to make a small change to the ExUnit configuration for formatters. Instead of only allowing a list of module names representing the GenServer we're going to use as formatters, we can also accept a tuple that contains the module name of our GenServer as well as configuration for that formatter. For example:

ExUnit.configure(formatters: [ExUnit.CLIFormatter, {CustomFormatter, %{print_results: false, email_results: true, api_key: System.get_env("API_KEY")}}])

Since then these options would be passed to our CustomFormatter when it's started, it would be easy enough for me to pick them up by doing:

def init(opts) do

  {_, my_opts} = Enum.find(opts[:formatters], {nil, %{}}, fn

    {__MODULE__, _} -> true

    _ -> false

  end)

  {:ok, my_opts}

end

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[José Valim]

Yes, we should document that the formatters receive all configuration and custom keys can be added on configure. +1

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