Add comprehensive unit tests for every function

[techwizrd]

Currently, developing Fishmarks is tricky because there are no unit tests to ensure that Fishmarks is working properly as new features are added or issues are fixed. Since Fishmarks works with text and has to make sure text is in a very specific format to be parsed, unit tests are a necessary to make sure that things like bookmark names are parsed that same way in every function and changes to the parsing system do not impact Fishmarks robust handling of bookmark names or user input.

However, there does not seem to be a clear standard for testing in Fish unlike JUnit for Java, unittest for Python, and RSpec for Ruby. The two solutions I can think of are running and writing Fishmarks tests using using the testing functionality of purpose programming language like Python or writing a test harness framework and unit testing library for Fish.