[Feature Request]: Add Unit Test for Metrics Module

[beesaferoot]

Preflight Checklist

• I have read the Contributing Guidelines for this project, if it exists.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Problem Description

Once #43 is merged. It would be great to have unit tests for the metrics feature similar to the token module.

Proposed Solution

Add a test file i.e metrics.test.js with unit tests for MetricsRequestHandler, MetricsResponseHandler and AuthMethod.

Alternatives Considered

No alternative solution was considered.

Additional Information

No response