Can't unit test procedural macros

[TadaHrd]

I have this test:

mod tests {
    use crate::str2code;
    #[test]
    fn test() {
        str2code!(r#"println!("Hello, world!");"#);
    }
}

The str2code macro is a procedural macro that I made.

#[proc_macro]
pub fn str2code(input: TokenStream) -> TokenStream

It gives this error:

error: can't use a procedural macro from the same crate that defines it
  --> src\lib.rs:31:9
   |
31 |         str2code!(r#"println!("Hello, world!");"#);
   |         ^^^^^^^^

Why does the compiler not let me test my macros and why does this exist?

[clubby789]

Procedural macros are essentially compiler plugins, and need to be compiled before they're used. As the error says, it can't us used within the crate it's defined in. You can instead define your tests in <project-dir>/tests/<file>.rs

[TadaHrd]

I get it now. I would have thought that the devs would put effort into making code easier for this.

[clubby789]

I've opend a PR to note a suggestion for tests