Prevent an empty list of custom regexes in the DetailsMenuMigration l…

…inter from reporting false positives (#2997)

.changeset/metal-shirts-sparkle.md

@@ -0,0 +1,5 @@
+---
+'@primer/view-components': patch
+---
+
+Prevent an empty list of custom regexes in the DetailsMenuMigration linter from reporting false-positives

lib/primer/view_components/linters/details_menu_migration.rb

@@ -32,9 +32,31 @@ def run(processed_source)
             # ERB nodes
             erb_nodes(processed_source).each do |node|
               code = extract_ruby_from_erb_node(node)
-              generate_node_offense(self.class, processed_source, node, MIGRATE_FROM_DETAILS_MENU) if (code.match?(DETAILS_MENU_RUBY_PATTERN) || code.match?(Regexp.new(@config.custom_erb_pattern.join("|"), true)))
+
+              if contains_offense?(code)
+                generate_node_offense(self.class, processed_source, node, MIGRATE_FROM_DETAILS_MENU)
+              end
             end
           end
+
+          def contains_offense?(code)
+            return true if code.match?(DETAILS_MENU_RUBY_PATTERN)
+            return code.match?(custom_erb_pattern) if custom_erb_pattern
+            false
+          end
+
+          def custom_erb_pattern
+            unless defined?(@custom_erb_pattern)
+              @custom_erb_pattern =
+                if @config.custom_erb_pattern.empty?
+                  nil
+                else
+                  Regexp.new(@config.custom_erb_pattern.join("|"), true)
+                end
+            end
+
+            @custom_erb_pattern
+          end
         end
       end
     end

test/lib/erblint/details_menu_migration_test.rb

@@ -38,6 +38,12 @@ def test_warns_if_details_menu_view_component_slot_is_rendered
     assert_match(/.<details-menu> has been deprecated./, @linter.offenses.first.message)
   end
 
+  def test_does_not_warn_if_no_details_menu_used
+    @file = "<% component.with_body('foo') %>"
+    @linter.run(processed_source)
+    assert_equal 0, @linter.offenses.count
+  end
+
   def test_does_not_warn_if_inline_disable_comment
     @file = <<~HTML
       <%= render SomeComponent.new(tag: :"details-menu") do %><%# erblint:disable Primer::Accessibility::DetailsMenuMigration %>