Mocking Diesel for unit tests

[naconnors]

Research discussion to document findings for mocking Diesel ORM to enable unit testing of API endpoints.

Currently, we are not aware of a good way to mock a database connection in Diesel similar to something you would do in unit tests in other languages.

[naconnors]

A possible solution would be to use Diesel's Connection::test_transaction to prevent changes to the database when running tests.

[jhodapp]

The one issue with this solution is to see how Diesel takes in a Connection so that it's still possible (and very easy) to run cargo test on our repo cloned locally. We should take a deeper look at Diesel's own internal use of test_transaction.

[naconnors]

Additional possible solution would be to use docker to create a throwaway test database to use and then destroy after running the integration tests.

[naconnors]

Additional possible solution would be to use sqlite3 for testing only. We could create the db, run migrations and then cleanup the db once testing is done.