Add network change events

[Gudahtt]

Description

The network controller now emits the events networkWillChange and networkDidChange when the network is being refreshed. The event networkWillChange is emitted before the switch begins (before the network status is cleared), and the networkDidChange event is emitted after the new provider is setup (but before it has finished initializing).

Changes

• ADDED: The events networkWillChange and networkDidChange are emitted during setProviderType, setActiveNetwork, resetConnection, and rollbackToPreviousProvider
  • The networkWillChange event is emitted before the network is switched (before the network status is cleared),
  • The networkDidChange event is emitted after the new provider is setup (but before it has finished initializing).

References

Closes #1210

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation for new or updated code as appropriate (note: this will usually be JSDoc)
• I've highlighted breaking changes using the "BREAKING" category above as appropriate

[Gudahtt]

I did originally intend for this PR to include the same coverage as the extension (in that we would ensure the networkDidChange event occurred after clearing state and after setting up the provider but before the network lookup)., but that quickly became complicated. I think it would be better to revisit that later as part of #1197, so that we can consider ways to cover that functionality without overly complicating the tests that we have.

[mcmire]

Looks good, just had a few minor notes.

[mcmire]

Nit: In a previous commit I added a toBeFulfilled matcher to make some of the existing tests in this repo more clear. Since the payload of the published event doesn't matter, I wonder if that matcher would be useful here too?

Suggested change

	const networkWillChange = await waitForPublishedEvents({
	messenger,
	eventType: 'NetworkController:networkWillChange',
	operation: () => {
	// Intentionally not awaited because we're capturing an event
	// emitted partway through the operation
	controller.rollbackToPreviousProvider();
	},
	});
	expect(networkWillChange).toStrictEqual([[]]);
	const promiseForNetworkWillChange = waitForPublishedEvents({
	messenger,
	eventType: 'NetworkController:networkWillChange',
	operation: () => {
	// Intentionally not awaited because we're capturing an event
	// emitted partway through the operation
	controller.rollbackToPreviousProvider();
	},
	});
	expect(promiseForNetworkWillChange).toBeFulfilled();

Similar for the other tests.

[Gudahtt]

Good idea! I might handle this in a follow-up PR though, since it applies to a lot of tests not covered in this PR

[Gudahtt]

Done here: #1347