message: Fix logger unit test when compiling w/o logging
diff: @@ -58,6 +58,8 @@ struct fixture {
  logger::line_format lf;
  };
  +constexpr const char* file_format = "%r %c %p %a %t %C %M %F:%L %m%n";
  +
  } // namespace <anonymous>
  CAF_TEST_FIXTURE_SCOPE(logger_tests, fixture)
  @@ -66,7 +68,7 @@ CAF_TEST_FIXTURE_SCOPE(logger_tests, fixture)
  // and finally serialization round-trip
  CAF_TEST(parse_default_format_strings) {
  actor_system sys{cfg};
  - CAF_CHECK_EQUAL(cfg.logger_file_format, "%r %c %p %a %t %C %M %F:%L %m%n");
  + CAF_CHECK_EQUAL(cfg.logger_file_format, file_format);
  add(logger::runtime_field);
  add(logger::plain_text_field, " ");
  add(logger::category_field);
  @@ -87,8 +89,11 @@ CAF_TEST(parse_default_format_strings) {
  add(logger::plain_text_field, " ");
  add(logger::message_field);
  add(logger::newline_field);
  + CAF_CHECK_EQUAL(logger::parse_format(file_format), lf);
  +#ifdef CAF_LOG_LEVEL
  + // Not parsed when compiling without logging enabled.
  CAF_CHECK_EQUAL(sys.logger().file_format(), lf);
  - CAF_CHECK_EQUAL(logger::parse_format("%r %c %p %a %t %C %M %F:%L %m%n"), lf);
  +#endif
  }
  CAF_TEST(rendering) {
  