Macro simulacrum_macros::create_expect_method

macro_rules! create_expect_method {
    ($name:ident($key:expr) $inputs:ty => $output:ty) => { ... };
    ($name:ident($key:expr) $inputs:ty) => { ... };
    ($name:ident($key:expr)) => { ... };
}

Use this macro to create an .expect_METHOD_NAME() method.