test: Added integration tests for the ValidateTheme macro

tests/enum_display_style_derive_integration_tests.rs

@@ -0,0 +1,15 @@
+use enum_display_style_derive::EnumDisplayStyle;
+use pretty_assertions::assert_str_eq;
+
+#[test]
+fn test_derive_enum_display_style() {
+  assert_str_eq!(TestEnum::Test.to_display_str(), "Testing 123");
+  assert_str_eq!(TestEnum::Ignored.to_display_str(), "Ignored");
+}
+
+#[derive(EnumDisplayStyle)]
+enum TestEnum {
+  #[display_style(name = "Testing 123")]
+  Test,
+  Ignored,
+}