Instead of reimplementing (yet again) a unittest only range, you could just use:
```D
auto mockRange(C)(C[] data)
{
    return map!(a => C(a))(data.representation);
}
```
Or, given it's only used in 2 places:

```D
auto r = map!(a => char(a))(`d:\dir\file`.representation); 
auto s = r.stripDrive(); 
foreach (i, c; `\dir\file`) 
    assert(s[i] == c); 
```

I'd have also recommended a simpler `Array!char.Range`, but that doesn't actually work right now :/