Developer sees unit test coverage for Littlepay v3 parsing

[ohrite]

As a developer making changes to the Littlepay V3 parse logic, When I make a breaking behavior change, I can run pytest and see a corresponding failure message

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Notes:

• Follow the example of other Operator tests in the airflow/tests/operators/ path
• Do not test the inside of the space capsule https://speakerdeck.com/skmetz/magic-tricks-of-testing-railsconf
• The result artifact should be in a predictable location, and containing the same information, given the inputs
• If your test depends on fixture data, such as a file at a specific location, make sure it’s there in setup
• More integration is better than less integration