added valid_source_type? search helper method & tests

Author: Oaphi

app/helpers/search_helper.rb

@@ -110,7 +110,7 @@ def params_to_qualifiers(params)
       filter_qualifiers.append({ param: :status, value: params[:status] })
     end
 
-    if SOURCE_TYPES.include?(params[:source]&.to_sym)
+    if valid_source_type?(params[:source])
       filter_qualifiers.append({ param: :source, value: params[:source].to_sym })
     end
 
@@ -243,4 +243,11 @@ def qualifiers_to_sql(qualifiers, query, user)
 
     query
   end
+
+  # Is a given param a valid source type?
+  # @param param [String, Symbol, nil] parameter to check
+  # @return [Boolean] check result
+  def valid_source_type?(param)
+    SOURCE_TYPES.include?(param&.to_sym)
+  end
 end

test/helpers/search_helper_test.rb

@@ -235,4 +235,14 @@ class SearchHelperTest < ActionView::TestCase
 
     assert_not(posts.any? { |p| p.category.id == admin_category.id })
   end
+
+  test 'valid_source_type? should correctly determine if the param is valid' do
+    SearchHelper::SOURCE_TYPES.each do |type|
+      assert valid_source_type?(type)
+    end
+
+    ['external', :source, nil].each do |invalid|
+      assert_not valid_source_type?(invalid)
+    end
+  end
 end