How to unit-test behavior under "version"?

[Andrey Zherikov]

On Wednesday, 30 March 2022 at 04:15:24 UTC, Paul Backus wrote:
> Probably the easiest way is to split it into two functions
>
> ```d
> void f()
> {
>     version (foo)
>         fVersionFoo();
>     else
>         fDefault();
> }
>
> void fVersionFoo()
> {
>     /* ... */
> }
>
> void fDefault()
> {
>     /* ... */
> }
> ```
>
> Then you can write separate unit tests for both `fVersionFoo` 
> and `fDefault`, and they will both be tested regardless of what 
> settings you build with.

This is an option when you have big difference between foo and 
not-foo behavior. In my case they are 90% the same so I think 
I'll go this way:

```d
void fImpl(bool fooMode)()
{
     static if(fooMode)
         writeln("foo");
     else
         writeln("no foo");
}

version(foo)
     alias f = fImpl!true;
else
     alias f = fImpl!false;

unittest {
     // test fImpl!true
}
unittest {
     // test fImpl!false
}
```