@Test
    void verifyRequestParamWithRegionUnderscore() {
        val request = new MockHttpServletRequest();
        request.addParameter("locale", "pt_BR");
        val response = new MockHttpServletResponse();
        val resolver = new SessionLocaleResolver();
        request.setAttribute(DispatcherServlet.LOCALE_RESOLVER_ATTRIBUTE, resolver);
        getInterceptor(false).preHandle(request, response, new Object());
        assertEquals(Locale.of("pt", "BR"), resolver.resolveLocale(request));
    }
This is {@link CasLocaleChangeInterceptorTests}.

@author Misagh Moayyed
@since 6.4.0
core/cas-server-core-web/src/test/java/org/apereo/cas/web/support/CasLocaleChangeInterceptorTests.java