Add unit:offset tests.

[boweiliu]

Description
Adds some unit tests for the unit: offset behavior.

Issue
Fixes: (link to issue)

Example
A GIF or video showing the old and new behaviors after this pull request is merged. Or a code sample showing the usage of a new API. (If you don't include this, your pull request will not be reviewed as quickly, because it's much too hard to figure out exactly what is going wrong, and it makes maintenance much harder.)

Context
If your change is non-trivial, please include a description of how the new logic works, and why you decided to solve it the way you did. (This is incredibly helpful so that reviewers don't have to guess your intentions based on the code, and without it your pull request will likely not be reviewed as quickly.)

Checks

• The new code matches the existing patterns and styles.
• The tests pass with yarn test.
• The linter passes with yarn lint. (Fix errors with yarn fix.)
• The relevant examples still work. (Run examples with yarn start.)
• You've added a changeset if changing functionality. (Add one with yarn changeset add.)

[changeset-bot]

⚠️ No Changeset found

Latest commit: 742d3bd

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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[boweiliu]

@dylans could i get some help running the workflows?

[dylans]

@boweiliu Thanks, always appreciate good quality tests getting added! It looks like you just need to run Prettier on your PR and then we should be ready to land it.

[dylans]

@boweiliu A reminder of my previous note:

Thanks, always appreciate good quality tests getting added! It looks like you just need to run Prettier on your PR and then we should be ready to land it.

[dylans]

@boweiliu quick reminder, run prettier on this and then we can land it.