Hello,

Is there a recommended way to automate testing for hand-written Stan functions?

For example, say I define a new Stan function:

```
functions {
real my_square(real x) {
return square(x);
}
```

I would like to verify that the output of this function is correct for a set of inputs via some sort of automated procedure.

So far, the two options I can think of are:

- Use the
`rstan`

interface and`expose_stan_functions`

to be able to directly call the function in R, at which point the output can be compared to some reference output. - Write a dummy model in Stan that serves only to execute the function on a set of inputs, and then outputs the results via
`print`

. You could perhaps implement this in a`generated data`

block, and have`parameters`

and`model`

be empty. The output could then be read externally and checked against some reference.

Are there any other options I’ve missed?

Thanks,

- Herb