Criando comandos no projeto https://github.com/serradura/slack-time-tracker

a_README.md

Links

• Primeiro slash command (calculadora) que fizemos: https://gist.github.com/serradura/ef3885d6ba736757150c
• Projeto de referência: https://github.com/samg/timetrap
• https://api.slack.com/slash-commands
• Ruby Explained: Procs, blocks and lambdas: http://www.eriktrautman.com/posts/ruby-explained-blocks-procs-and-lambdas-aka-closures
• Diff between block, procs and lambdas: http://awaxman11.github.io/blog/2013/08/05/what-is-the-difference-between-a-block/
• RubyMonk with running codes: https://rubymonk.com/learning/books/4-ruby-primer-ascent/chapters/18-blocks/lessons/64-blocks-procs-lambdas

Template Method

https://en.wikipedia.org/wiki/Template_method_pattern

Exemplo em coffeescript:

class Template
  constructor: (@name) ->

  greet: -> throw "NotImplementedError"

command = new Template("foo")
command.greet()

class Polite extends Template
  greet: -> "Hello #{@name}"

command = new Polite("foo")
alert command.greet()

slash_command.rb

# app/lib/slash_command.rb

module SlashCommand
  Invoke.setup help: Commands::Help,
               default: Commands::Default,
               unknown: Commands::Unknown,
               available: [
                 Commands::Sum, # NEW COMMAND
                 Commands::In,
                 Commands::Out,
                 Commands::Now,
                 Commands::Edit,
                 Commands::Kill,
                 Commands::Resume,
                 Commands::Display,
                 Commands::Today,
                 Commands::Yesterday
               ]
end

sum.rb

# app/lib/slash_command/commands/sum.rb

# frozen_string_literal: true

module SlashCommand
  module Commands
    class Sum < Template
      NAME = "sum"
      DESC = "Sum two numbers"
      HELP = "e.g: sum 1 1"

      def call
        response.result = data.split.map(&:to_i).reduce(&:+)
      end
    end
  end
end

sum_command_spec.rb

# spec/requests/api/v1/commands/invoke/sum_command_spec.rb

# Running the test: rspec spec/requests/api/v1/commands/invoke/sum_command_spec.rb

require "rails_helper"

RSpec.describe "POST /api/v1/commands/invoke", type: :request do
  describe "sum command" do
    let(:payload) { create(:slack_payload, text: "sum 1 2 3") }

    before do
      post api_v1_commands_invoke_path, payload.to_h
    end

    it "responds with a valid sum" do
      expect(response).to have_http_status(200)
      expect(response.body).to be == "6"
    end
  end
end

Ruby Explained: Procs, blocks and lambdas - http://www.eriktrautman.com/posts/ruby-explained-blocks-procs-and-lambdas-aka-closures
Diff between block, procs and lambdas - http://awaxman11.github.io/blog/2013/08/05/what-is-the-difference-between-a-block/
RubyMonk with running codes - https://rubymonk.com/learning/books/4-ruby-primer-ascent/chapters/18-blocks/lessons/64-blocks-procs-lambdas (edited)