Java Interface Unit Functionality Checkup

As part of our ongoing development process, we're in need of professional support for unit testing, specifically targeting the interface units of our Java project.

Key tasks:

- Analyze and inspect elements of the interface to ensure complete functionality.
- Implement JUnit testing frameworks to perform comprehensive tests on these units.
- Rectify any detected errors to sustain a high-quality code environment.

Ideal candidate should hold:

- Profound expertise in Java interface unit testing.
- An excellent command of JUnit testing frameworks.
- Outstanding problem-solving abilities to rectify any detected errors.

Final goal is to achieve a smooth interfacing experience for the users by ensuring top-notch functionality of the interface units.