Include view/helpers in RSpec tests

class MyPresenter
  def initialize(view_context)
    @view_context = view_context
  end

  def human_file_size
    @view_context.number_to_human_size(1500, precision: 1)
  end
end

RSpec.describe MyPresenter do
  include ActionView::TestCase::Behavior

  it do
    expect(described_class.new(view).file_size_human).to eq "1.5 KB"
  end
end