Add integration tests

[Nightfirecat]

Given past issues with cards with special characters—and the edge cases therein—and the implementation of error handling, we may benefit from starting to write a set of test cases to ensure we don't introduce regressions or partial fixes to these issues. (ref: #19, #24)

Since we can identify cards by their card name, we could confirm their inclusion in the computed deck list after parsing some given text. This would be a more secure and automated method of testing problem cases, rather than confirming by-eye.

IMO, this is a low-priority effort, but would be worth putting effort toward at some point in the future.

[Nightfirecat]

We may be able to begin adding unit tests with the parsing changes of #42.