I guess you have to understand the implementation to understand this error…

foo_spec.rb

describe ActiveSupport::TimeZone do
  it "has an invalid fraction, clearly" do
    rub_a_dub_double = double.as_null_object
    ymd = [rub_a_dub_double.year, rub_a_dub_double.month, rub_a_dub_double.day]
    
    ActiveSupport::TimeZone['UTC'].local(*ymd) # ArgumentError: invalid fraction
    Date.new(*ymd) # => ArgumentError: invalid date -- now that makes sense
  end
end

Leaflet

Leaflet