Sync Rectangles tests with problem spec

[themetar]

Added a missing test from problem specification.

[github-actions]

This PR touches files which potentially affect the outcome of the tests of an exercise. This will cause all students' solutions to affected exercises to be re-tested.

If this PR does not affect the result of the test (or, for example, adds an edge case that is not worth rerunning all tests for), please add the following to the merge-commit message which will stops student's tests from re-running. Please copy-paste to avoid typos.

[no important files changed]

For more information, refer to the documentation. If you are unsure whether to add the message or not, please ping @exercism/maintainers-admin in a comment. Thank you!

[github-actions]

Hello. Thanks for opening a PR on Exercism 🙂

We ask that all changes to Exercism are discussed on our Community Forum before being opened on GitHub. To enforce this, we automatically close all PRs that are submitted. That doesn't mean your PR is rejected but that we want the initial discussion about it to happen on our forum where a wide range of key contributors across the Exercism ecosystem can weigh in.

You can use this link to copy this into a new topic on the forum. If we decide the PR is appropriate, we'll reopen it and continue with it, so please don't delete your local branch.

If you're interested in learning more about this auto-responder, please read this blog post.

---

Note: If this PR has been pre-approved, please link back to this PR on the forum thread and a maintainer or staff member will reopen it.

[SleeplessByte]

/format

[github-actions]

The "Format code" action has started running.

[github-actions]

The "Format code" action has finished running.

[github-actions]

For security reasons, /format does not trigger CI builds when the PR has been submitted from a fork. If checks were not passing due to code format, trigger a build to make the required checks pass, through one of the following ways:

• Push an empty commit to this branch: git commit --allow-empty -m "Trigger builds".
• Close and reopen the PR.
• Push a regular commit to this branch.