Revert "Wrong tests"
Revert "Wrong tests"

This reverts commit b39d0309aa7358f052b82ce5df592c1570cee26b.

The tests were not wrong; the documentation was confusing. See
discussion in https://github.com/exercism/rust/pull/823 for details.

exercism/xrust,petertseng/exercism-rust,exercism/xrust,petertseng/exercism-rust,petertseng/exercism-rust