Fixed the failing tests

# What Changed
The test suite

# Why?
It looks like the code was looking for a `String` object so that it could determine if it was going to use a `FakeSerialPort` or a real `SerialPort`. From what I understood about the test code / implementation code, this fix should be accurate. Prior to the fix, the test suite had 10 errors.

Let me know if I was off on this one and I will patch it up accordingly.