Modify new interactor's argument list to handle some cases

[tokichie]

Hi, I'm using hanami for my new project, and I love it. Thank you for a cool framework.
I've noticed that new interactor interface (from 1.1) cannot handle some argument patterns.
I propose a solution to handle such cases.

case 1: no keyword arguments
In this case, the actual arguments passed to #call is ['foo', 'bar', {}]
This can be avoided to change #call args to call(foo, bar, *) but i think it is not cool 🤔

class FooInteractor
  include Hanami::Interactor
  def call(foo, bar)
  end
end

[3] pry(main)> interactor = FooInteractor.new
=> #<FooInteractor:0x007f9d2797ef98>
[4] pry(main)> interactor.call('foo', 'bar')
ArgumentError: wrong number of arguments (given 3, expected 2)
from (pry):4:in `call'

case 2: no keyword arguments and an argument with #to_hash method
In this case, the last argument is converted into Hash automatically if it implements #to_hash.
Because Hanami::Entity implements #to_hash, this case may happen often, and makes the behavior unexpected 😢

class FooInteractor
  include Hanami::Interactor
  def call(foo, bar)
    p foo, bar
  end
end

class Foo < Hanami::Entity; end
class Bar < Hanami::Entity; end

[8] pry(main)> foo = Foo.new(foo: 'foo')
=> #<Foo:0x007fb0513f2380 @attributes={:foo=>"foo"}>
[9] pry(main)> bar = Bar.new(bar: 'bar')
=> #<Bar:0x007fb051369378 @attributes={:bar=>"bar"}>
[10] pry(main)> interactor.call(foo, bar)
#<Foo:0x007fb0513f2380 @attributes={:foo=>"foo"}>
{:bar=>"bar"}
^^^^^^^^^^^^^ Bar is converted into a hash
=> #<Hanami::Interactor::Result:0x00007fb0512db1b8 @success=true @payload={}>

[cllns]

Thanks for this PR :)

@TiteiKo You worked on changing the args. What do you think about this change?

[jodosha]

@tokichie Thanks for this PR. I manually tested these new cases and they work well.

The following script fails with hanami-utils 1.1.0 (aka master). But it works as expected with your branch.

require "bundler/setup"
require "hanami/interactor"

class FooInteractor
  include Hanami::Interactor

  def call(foo, bar)
    puts foo
    puts bar
  end
end

FooInteractor.new.call(1, 2)

class Entity
  def initialize(attributes)
    @attributes = attributes
  end

  def to_hash
    @attributes
  end
end

class BarInteractor
  include Hanami::Interactor

  def call(entity)
    puts entity.inspect
  end
end

entity = Entity.new(name: "Luca")
BarInteractor.new.call(entity)

class BazInteractor
  include Hanami::Interactor

  def call(foo:, bar: 2)
    puts foo
    puts bar
  end
end

BazInteractor.new.call(foo: 1)
BazInteractor.new.call(foo: 1, bar: 30)

begin
  BazInteractor.new.call(bar: 4)
rescue ArgumentError
  puts "This raises an error because `foo' is missing"
end