Chore: introduce Fishery as object factory and yarn dev:msw

[VikaCep]

Closes: #850

This PR introduces the following changes:

Fishery: Simplifies mocking data in tests, removing the need for hard-coded objects. It works alongside Faker to automatically generate dynamic test data for more flexible testing scenarios.

It defines factories for:

• All different check types
• Probes
• Check alerts

These factories are used to create fixtures in src/test/fixtures/probes.ts, src/test/fixtures/checks.ts, and src/test/fixtures/checkAlerts.ts.

Mocked API responses: Adds the ability to start the app with mocked API responses. To use this, run yarn dev:msw. This runs a service worker that uses the same handlers as in test .

Example of running the app using MSW mocked responses:

Screen.Recording.2024-12-20.at.15.44.15.mov

[ckbedwell]

This is ace but there are some things we can tighten up! 🔧

[ckbedwell]

I think this should be opinionated and generate Private probes by default. I was experimenting with the probe definitions and found this was a source of flaky tests because the app behaviour changes dependent on if they are public or private probes.

[ckbedwell]

As per my comment below on reflecting upon this, I think we should have two factories. One that creates public probes and one that creates private probes.

[VikaCep]

I tried creating two separate factories—one for PrivateProbes and one for PublicProbes—but since the IDs for public and private probes can’t overlap, we need to manage their creation within a single factory. This requires using a transient parameter, similar to how it’s done with checks. But having two separate factories was complicating things, so I found it more straightforward to just use one factory that creates private probes by default. For fixtures that require a public probe, we can simply set the public: true property.

[ckbedwell]

One thing to change then let's get this in! 🎉

[ckbedwell]

Just needs a small modification so it gets tree-shaken properly and doesn't affect the production bundle size:

1. Move line 33 and associated imports to a file like startServerWorker.ts:

import { setupWorker } from 'msw';
import { handlers } from 'test/handlers';

setupWorker(...handlers).start();

2. change line 33 to: await import(./startServiceWorker);

Then we don't include the additional 850kb overhead our mocks have 😄

[ckbedwell]

LGTM ❤️