@DisplayName("Edge Cases and Boundary Tests")
    class EdgeCasesTests {

        @ParameterizedTest
        @NullAndEmptySource
        @DisplayName("Should handle null and empty domains")
        void testNullAndEmptyDomains(String domain) {
            referralData.setDomain(domain);
            assertEquals(domain, referralData.getDomain());
        }

        @ParameterizedTest
        @NullAndEmptySource