@Test
    void verifyOperationByDefaultValue() throws Throwable {
        val themeDir = new File(FileUtils.getTempDirectory(), "test");
        if (!themeDir.exists() && !themeDir.mkdir()) {
            fail(() -> "Unable to create directory " + themeDir);
        }
        val path = new File(themeDir, "casLoginView.html");
        FileUtils.write(path, "<html><html>", StandardCharsets.UTF_8);

        val themeResolver = new FixedThemeResolver();
        themeResolver.setDefaultThemeName("test");
        val resolver = new ThemeFileTemplateResolver(casProperties, themeResolver);
        resolver.setSuffix(".html");
        resolver.setCheckExistence(true);
        resolver.setPrefix(FileUtils.getTempDirectoryPath() + "/%s/");
        val view = resolver.resolveTemplate(mock(IEngineConfiguration.class), StringUtils.EMPTY, "casLoginView", Map.of());
        assertNotNull(view);
    }
This is {@link ThemeFileTemplateResolverTests}.

@author Misagh Moayyed
@since 6.2.0
support/cas-server-support-thymeleaf/src/test/java/org/apereo/cas/web/view/ThemeFileTemplateResolverTests.java