Fix route namespace singularization for plural module names

[rameerez]

While trying to integrate madmin into my project which also uses the pricing_plans and usage_credits gems, I started getting errors like these on any madmin page, none was loading:

undefined method 'madmin_usage_credit_wallets_path'

I came across all these errors just by following the README instructions, so I thought it could be a bug, which I think it is. Fortunately, it seems like it's just a single line.

The problem was the .singularize call in here:

madmin/lib/madmin/resource.rb

Line 87 in 5b481d6

@route_namespace = (namespace ? namespace.name.singularize.underscore.to_sym : nil)

Which incorrectly transforms plural namespace module names. Both pricing_plans and usage_credits have multiple namespaced models, which get incorrectly converted by madmin:

• PricingPlans → PricingPlan → :pricing_plan (should be :pricing_plans)
• UsageCredits → UsageCredit → :usage_credit (should be :usage_credits)

This caused undefined method errors like: undefined method 'madmin_pricing_plan_assignments_path' (expected: 'madmin_pricing_plans_assignments_path')

The bug probably went undetected because Rails' built-in engines work because they're singular: ActionText, ActiveStorage, ActionMailbox don't change when singularized. Also the test suite only tests ActionText::RichTextResource, which doesn't expose the bug.

This affects all four path methods (index, new, show, edit) for any namespaced model with a plural namespace name.

After the fix all tests pass, and I also tested it manually in my app while using my other gems and now everything works fine!

[excid3]

I remember adding that for some reason, but it's been so long I don't remember. I'll test this on a couple of our apps and make sure it works.

Edit: Seems fine!