add testing for incorrect resolution

spec/factories/site_settings.rb

@@ -25,6 +25,11 @@
       favicon { Rack::Test::UploadedFile.new("app/assets/images/icons/favicon-48x48.png", IMAGE_TYPE) }
     end
 
+    trait :invalid_favicon do
+      title { "ZeroWaste" }
+      favicon { Rack::Test::UploadedFile.new("spec/fixtures/icons/favicon-181x181.png", IMAGE_TYPE) }
+    end
+
     trait :custom_setting do
       title { "Custom Waste" }
       favicon { Rack::Test::UploadedFile.new("app/assets/images/user.png", IMAGE_TYPE) }

spec/models/site_setting_spec.rb

@@ -16,7 +16,7 @@
 
     before { subject.update(site_setting_params) }
 
-    let(:site_setting_params) { FactoryBot.attributes_for(:site_setting, :with_valid_site_setting) }
+    let(:site_setting_params) { attributes_for(:site_setting, :with_valid_site_setting) }
 
     it "has a valid factory" do
       is_expected.to be_valid
@@ -79,5 +79,16 @@
         )
       end
     end
+
+    context "with a favicon larger than 180x180 pixels" do
+      let(:site_setting_params) { attributes_for(:site_setting, :invalid_favicon) }
+
+      it "is not valid" do
+        is_expected.not_to be_valid
+        expect(subject.errors.messages[:favicon]).to include(
+          I18n.t("errors.messages.dimension_width_less_than_or_equal_to", length: 180)
+        )
+      end
+    end
   end
 end