Fix Failing Tests

My tests are failing and I can't figure out why:

TEST FILE:
[Paste the test code]

IMPLEMENTATION:
[Paste the code being tested]

FAILURE OUTPUT:
[Paste the test failure message]

The test passed before: [recent changes, or "it never passed"]

What I think should happen: [your expectation]

Please:
1. Explain why the test is failing
2. Identify whether the bug is in the test or implementation
3. Provide the fix