pub fn from_str(_: &str) -> String {
        panic!("not available with cfg(test)");
    }
Converts a slice of bytes to a string, including invalid characters.

Strings are made of bytes ([`u8`]), and a slice of bytes
([`&[u8]`][byteslice]) is made of bytes, so this function converts
between the two. Not all byte slices are valid strings, however: str
benchmarks/haystacks/code/rust-library.rs