Function ffi_utils::test_utils::call_2

pub unsafe fn call_2<F, E0, E1, T0, T1>(f: F) -> Result<(T0, T1), i32> where
    F: FnOnce(*mut c_void, extern "C" fn(_: *mut c_void, _: FfiResult, _: T0::C, _: T1::C)),
    E0: Debug,
    E1: Debug,
    T0: ReprC<Error = E0>,
    T1: ReprC<Error = E1>, 

Call a FFI function and block until its callback gets called, then return the argument which were passed to that callback. Use this if the callback accepts two arguments in addition to user_data and error_code.