Test serializers

[nickpfeiffer05]

Purpose

Added unit and integration tests for the recently refactored serializers. We previously had no serializer tests, and these tests will ensure that any future changes to the serializers will not produce unintended results.

Contributors

@nickpfeiffer05

Feature List

• Added testing files integration.test.ts and unit.test.ts in the serializers testing folder. Produced sample course data for testing in the fixtures folder
• Wrote unit tests for the bulkSerialize method of all serializers
• Wrote integration tests for graphQL -> bulkSerialize method of all serializers. This ensures that all course data retrieved from database data is serialized correctly.

Reviewers

Primary reviewer:

Primary:

@ananyaspatil

Secondary reviewers:

Secondary:

@Anzhuo-W @mehallhm @cherman23

[coveralls]

coverage: 80.391% (+0.2%) from 80.173%
when pulling 33d52df on test-serializers
into 561f7ea on master.

[mehallhm]

Instead of unit.test.ts and integration.test.ts could you please instead put each test type in the appropriate directory and renamed to something more descriptive to their role for the serializers. I understand that the fixtures need to be shared, so those can just live in the tests dir. That way our integration and unit tests don't get jumbled together

[mehallhm]

Does this PR succeed #220? If so, can you please clean it up to prepare for the changes here.

[mehallhm]

Given what we discussed, we should move forward with the way it is now and refactor all of the tests at a later date