Personally, I'd break this into multiple lines (e.g. putting the `n = n, n_minus_1 = n - 1` on to a new line). At least, the style in the main Rust code-base is to limit lines to 100 columns; in the case of long strings it doesn't particularly matter, but hiding logic (i.e. something other than more string) at the end is less than nice.

(Also, if you didn't know, Rust allows newlines inside strings:

```rust
     format!("{n} bottles of beer on the wall, {n} bottles of beer.
Take one down and pass it around, {n_minus_1} bottles of beer on the wall
", n = n, n_minus_1 = n - 1)
```

I guess this might make the tests clearer.)