Raise error uncountable slot names in plural slots (#1904)

* Raise error when uncountable slot names are used in `renders_many`

    *Hugo Chantelauze*
    *Reegan Viljoen*

docs/CHANGELOG.md

@@ -10,6 +10,11 @@ nav_order: 5
 
 ## main
 
+* Raise error when uncountable slot names are used in `renders_many`
+
+    *Hugo Chantelauze*
+    *Reegan Viljoen*
+
 * Replace usage of `String#ends_with?` with `String#end_with?` to reduce the dependency on ActiveSupport core extensions.
 
     *halo*

lib/view_component/errors.rb

@@ -149,6 +149,16 @@ def initialize(klass_name, slot_name)
     end
   end
 
+  class UncountableSlotNameError < InvalidSlotNameError
+    MESSAGE =
+      "COMPONENT declares a slot named SLOT_NAME, which is an uncountable word\n\n" \
+      "To fix this issue, choose a different name."
+
+    def initialize(klass_name, slot_name)
+      super(MESSAGE.gsub("COMPONENT", klass_name.to_s).gsub("SLOT_NAME", slot_name.to_s))
+    end
+  end
+
   class ContentAlreadySetForPolymorphicSlotError < StandardError
     MESSAGE = "Content for slot SLOT_NAME has already been provided."
 

lib/view_component/slotable.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "active_support/concern"
+require "active_support/inflector/inflections"
 require "view_component/slot"
 
 module ViewComponent
@@ -295,6 +296,7 @@ def validate_plural_slot_name(slot_name)
           raise ReservedPluralSlotNameError.new(name, slot_name)
         end
 
+        raise_if_slot_name_uncountable(slot_name)
         raise_if_slot_conflicts_with_call(slot_name)
         raise_if_slot_ends_with_question_mark(slot_name)
         raise_if_slot_registered(slot_name)
@@ -330,6 +332,13 @@ def raise_if_slot_conflicts_with_call(slot_name)
           raise InvalidSlotNameError, "Slot cannot start with 'call_'. Please rename #{slot_name}"
         end
       end
+
+      def raise_if_slot_name_uncountable(slot_name)
+        slot_name = slot_name.to_s
+        if slot_name.pluralize == slot_name.singularize
+          raise UncountableSlotNameError.new(name, slot_name)
+        end
+      end
     end
 
     def get_slot(slot_name)

test/sandbox/test/slotable_test.rb

@@ -720,6 +720,17 @@ def test_slot_with_content_shorthand
     assert component.title.content?
   end
 
+  def test_slot_with_unplurialized_name
+    exception =
+      assert_raises ViewComponent::UncountableSlotNameError do
+        Class.new(ViewComponent::Base) do
+          renders_many :series
+        end
+      end
+
+    assert_includes exception.message, ""
+  end
+
   def test_slot_names_cannot_start_with_call_
     assert_raises ViewComponent::InvalidSlotNameError do
       Class.new(ViewComponent::Base) do