🥗 Marketplace: Spec for Product#tags

- #2189

Lil' quick sketch through the workflow. Only interesting things of note
here are I am using `scenario` syntax (which feels better to me, and was
validated by @ExMember in antoher context yesterday.)

I am also doing something "weird" where I overload the `visit` method to
rely on our `Record#location` method to interject a `polymorphic_path`
call; saving us the burden of including the `polymorphic_path` call on
our own every time we use `visit`; but adding the burden of a layer of
indirection.

I also did this with `within`, because omg that awkward
`"##{dom_id(model)"` drives me nuts every time I type it. It makes me
want to scream. I can't stand it.

spec/furniture/marketplace/product_tags_system_spec.rb

@@ -0,0 +1,46 @@
+require "rails_helper"
+
+describe "Product Tags", type: :system do
+  let(:space) { create(:space, :with_entrance, :with_members) }
+  let(:marketplace) { create(:marketplace, :ready_for_shopping, room: space.entrance) }
+
+  before do
+    sign_in(space.members.first, space)
+  end
+
+  scenario "Adding Tags to a Product" do # rubocop:disable RSpec/Capybara/FeatureMethods,RSpec/ExampleLength
+    muffins = create(:marketplace_product, marketplace:, name: "Mazin' Muffins", description: "Buttery corn muffins")
+
+    visit(marketplace)
+    click_link("Tags")
+
+    click_link("Add Tag")
+
+    fill_in("Label", with: "🚫🌾 Gluten Free")
+
+    click_button("Create")
+
+    click_link("Products")
+    within(muffins) do
+      click_link("⚙️ Edit")
+    end
+
+    visit(marketplace)
+
+    within(muffins) do
+      expect(page).to have_content("🚫🌾 Gluten Free")
+    end
+  end
+
+  def visit(object_or_path)
+    if object_or_path.respond_to?(:location)
+      super(polymorphic_path(object_or_path.location))
+    else
+      super
+    end
+  end
+
+  def within(model, *, **, &block)
+    page.within("##{dom_id(model)}", *, **, &block)
+  end
+end