position , which is why there expectedformat argument must be a string literal "quote your inlined format argument to use as string literal", you might be missing a string literal to format with{:?} {} printf formatting is not supported; see the documentation for `std::fmt`format specifiers use curly bracesshell formatting is not supported; see the documentation for `std::fmt`format specifiers use curly braces, and formatting specifier missing or variants where every field has a default value