Struct Generator generates normal Map

[maennchen]

I have a relatively complex generator (which is not even complete by now).

@cron_expression_value list(of:
  choose(from: [
    value(:*),
    int(),
    tuple(like: {value(:L), int()})
  ]
), min: 1, max: 3)

test "parse & compose gets the same struct" do
  ptest [cron_expression: Pollution.VG.struct(%Crontab.CronExpression{
    extended: value(false),
    reboot: value(false),
    second: value([:*]),
    minute: @cron_expression_value,
    hour: @cron_expression_value,
    day: @cron_expression_value,
    month: @cron_expression_value,
    weekday: @cron_expression_value,
    year: @cron_expression_value
  })] do
    IO.inspect cron_expression
    cron_string = Crontab.CronExpression.Composer.compose(cron_expression)
    assert Crontab.CronExpression.Parser.parse!(cron_string, false) == cron_expression
  end
end

I expect this code to always generate the cron_expression property as a struct of Crontab.CronExpression.

$ mix test
.............................................................................................~e[* 0L,0 0L,-1L 0L 0,*,0L *]
~e[* 0L,0 0L,-1L 0L 0,*,0L *]
%{day: [L: 0, L: -1], extended: false, hour: [{:L, 0}, 0], minute: [:*],
  month: [L: 0], reboot: false, second: [:*], weekday: [0, :*, {:L, 0}],
  year: [:*]}


  1) test parse & compose gets the same struct (Crontab.FunctionalTest)
     test/crontab/functional_test.exs:140
     ** (FunctionClauseError) no function clause matching in Crontab.CronExpression.Composer.compose/1
     stacktrace:
       (crontab) lib/crontab/cron_expression/composer.ex:26: Crontab.CronExpression.Composer.compose(%{day: [L: 0, L: -1], extended: false, hour: [{:L, 0}, 0], minute: [:*], month: [L: 0], reboot: false, second: [:*], weekday: [0, :*, {:L, 0}], year: [:*]})
       test/crontab/functional_test.exs:153: anonymous fn/1 in Crontab.FunctionalTest.test parse & compose gets the same struct/1
       lib/pollution/shrinker.ex:41: Pollution.Shrinker.shrink/3
       lib/quixir/shrinker.ex:48: Quixir.Shrinker.try_to_shrink/2
       lib/quixir/shrinker.ex:31: Quixir.Shrinker.start_shrink/1
       test/crontab/functional_test.exs:141: anonymous fn/2 in Crontab.FunctionalTest.test parse & compose gets the same struct/1
       (elixir) lib/enum.ex:1785: Enum.reduce_range_inc/4
       test/crontab/functional_test.exs:141: (test)

....................................

Finished in 0.4 seconds
130 tests, 1 failure

Randomized with seed 522066

The output shows, that in some cases the cron_expression is just a map and not of type struct Crontab.CronExpression.

I'm not certain, that I did everything correct, but it seems like an error to me.