chore: Add jest unit testing

[jfoo1984]

Pull Request

JIRA Ticket

CZID-9015

Description

Add unit tests based on graphQL mesh examples.

• Set up jest and related config
• Tests added:
  • tests/UnifiedSchema.test.ts
  • tests/ZipLinkQuery.test.ts

Notes

I originally mocked data with the mock plugin, but it was pointed out that this doesn't test our resolvers. I've switched approaches to mock data retrieval methods called by the resolvers. But I created a branch with the mock store approach, in case we want to use that in the future: https://github.com/chanzuckerberg/czid-graphql-federation-server/tree/testing-mock-store-example

Tests

This PR adds automated tests

[jfoo1984]

Align to schema returned by resolver. This was preventing the tests from running, because the schema could not be generated

[jfoo1984]

Align to schema returned by resolver. This was preventing the tests from running, because the schema could not be generated

[jfoo1984]

Since #61 was closed in favor of this PR, I am pulling this change in that was there.

[jfoo1984]

this is in preparation for changing the release cadence. stop pushing every PR to staging

[rainandbare]

I like it Jerry! Great work!

I couldn't quite make the Ziplink test fail on its own unless I deleted it from the yaml so maybe we would have to write more specific tests? But even having the unified schema test is a logical and important safe guard.

Anything we can do about these messages?

[jfoo1984]

I was able to remove the mock plugin, and instead, use jest mocking of our httpUtil function to actually test the resolvers instead of bypassing them. This is probably a better test pattern we should use, given how much code we have in resolvers

The warnings are a type issue in the mock plugin, which I've raised with The Guild team. With the removal of the mock plugin though, the warnings should no longer appear

[jfoo1984]

I verified locally that changing code in the ZipLink resolver (to return a different response) does break the test.

[rainandbare]

I think this looks great Jerry! Are you worried that it is too much work per test?

[jfoo1984]

I think this looks great Jerry! Are you worried that it is too much work per test?

Thanks for reviewing @rainandbare! Are you referring to added engineering work to write these tests? My thought is that the amount of work to add these tests is inline with what I would expect for writing unit tests. It does add overhead per feature we develop, but I think it's worth it for future maintainability of the system. Hopefully, additional tests can follow the same patterns, and require less lift than this one did.