warning: the borrowed expression implements the required traits
  --> src/rolling/tests.rs:89:19
   |
89 |             .open(&filepath)
   |                   ^^^^^^^^^ help: change this to: `filepath`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrows_for_generic_args
   = note: `#[warn(clippy::needless_borrows_for_generic_args)]` on by default