AO3-5717 Fix expected chapter count lower than actual count

[luis-pabon-tf]

Pull Request Checklist

Issue

https://otwarchive.atlassian.net/browse/AO3-5717

Purpose

Uses an existing virtual attribute so that the chapter count safeguards happen even if the chapter count provided is wrong.

Testing Instructions

In the JIRA ticket.

Credit

What name and pronouns should we use to credit you in the Archive of Our Own's Release Notes?

bird - (they)

[redsummernight]

Can you add a test for this behavior of wip_length? In spec/models/work_spec.rb, we can have a block for describe "#wip_length=" and check that setting the attribute to e.g. 2 for a work with 1 chapter will end up with both expected_number_of_chapters and wip_length at 1.

[tickinginstant]

Would you mind removing expected_number_of_chapters from the work_params function in WorksController, as well?

otwarchive/app/controllers/works_controller.rb

Lines 893 to 896 in 72b975c

	def work_params
	params.require(:work).permit(
	:rating_string, :fandom_string, :relationship_string, :character_string,
	:archive_warning_string, :category_string, :expected_number_of_chapters,

Otherwise someone would still be able to manipulate the HTML to get an invalid chapter count.

[redsummernight]

Looks good, thanks!