GraphQLTestHelper Proposal

require 'pry'

module GraphQLTestHelper
  def on_mutation(args: {}, &mutation_tests_block)
    mutation, response = mutation_query(args: args, &mutation_tests_block)

    puts mutation.selections # [{:script_tag=>[:src, :display_scope]}]

    MutationEvaluator.new(self, response) do
      @mutation = mutation
      instance_exec(&mutation_tests_block)
    end
  end

  private

  def mutation_query(args: {}, &mutation_tests_block)
    mutation = MutationGenerator.new(args, &mutation_tests_block)

    response = Requestor.new(mutation).response

    [mutation, response]
  end
end

class ScriptTagCreateTest
  include GraphQLTestHelper

  def test
    on_mutation args: { input: { src: "https://hello.com/bar.js" }} do
      assert_no_errors
      assert_no_user_errors

      on_return_field :script_tag do
        assert_field "https://hello.com/bar.js", :src
        assert_field "ONLINE_STORE", :display_scope
      end
    end
  end
end

class MutationGenerator
  attr_accessor :selections

  def initialize(args, &mutation_tests_block)
    @args = args
    @selections = []

    instance_exec(&mutation_tests_block)

    # continue to create the mutation like normal using selections and passed in args
  end

  def assert_field(expected, field_name)
    @current_selection[@current_field_name].push(field_name.to_sym)
  end

  def on_return_field(field_name, &field_assertions)
    @current_selection = Hash.new
    @current_field_name = field_name
    @current_selection[@current_field_name] = []

    instance_exec(&field_assertions)

    @selections.push(@current_selection)
  end

  def assert_no_user_errors
    # no op
  end

  def assert_no_errors
    # no op
  end
end

class MutationEvaluator
  def initialize(execution_context, response, &block)
    @execution_context = execution_context
    @response = response
    #...
    instance_exec(&block)
  end

  def assert_no_errors
    #...
  end

  def assert_no_user_errors
    #...
  end

  def on_return_field(field_name, &block)
    #...
  end

  def assert_field(field_name, expected = nil, &block)
    #...
  end
end

class Requestor
  attr_accessor :response

  def initialize(mutation)
    @query = mutation
    @response = "my response"
    #...
  end
end

script_tag_test = ScriptTagCreateTest.new
script_tag_test.test