### Question:
LogHelper extends BasicValueHelper { public static Builder builder() { return new Builder(); } LogHelper(LoggerAdapter adapter, Level defaultLevel,
            boolean appendTemplateInfo); @Override void execute(Options options); static Builder builder();  }### Answer:
@Test public void testLogHelperValidation() { final MustacheEngine engine = MustacheEngineBuilder.newBuilder() .registerHelpers(HelpersBuilder.empty() .add("log", LogHelper.builder().build()).build()) .build(); MustacheExceptionAssert .expect(MustacheProblem.COMPILE_HELPER_VALIDATION_FAILURE) .check(() -> engine.compileMustache("log_helper_validation01", "{{#log \"Foo\"}}{{/log}}")) .check(() -> engine.compileMustache("log_helper_validation02", "{{log}}")); }