Fix pull request list not updating

[niik]

Description

I noticed recently that the PR list for a repository was missing the most recent PR or two. It only happened intermittently but I was recently able to reproduce it and found that due to a bug in the PullRequestCoordinator (which has been there since the beginning) it would fail to emit an update when the PR list for a repository changed. Story time.

In #11063 we significantly reduced the number of times the repository store emits an update signaling to the rest of the app that the list of repositories has changed (i.e. a repository was added, removed, or its information was updated). See e14db86#diff-efb525e0e38f508020a700c360ea248af1b2a6f0c5cb44f728830acbecbccbe3 for one such example.

When the PullRequestStore refreshes the list of PRs for a repository it emits an event

desktop/app/src/lib/stores/pull-request-store.ts

Line 221 in cf603e8

this.emitPullRequestsChanged(repository, await this.getAll(repository))

Which is then caught by the PullRequestCoordinator which figures out which Repository models needs to be updated as a result of the PR Store refreshing PRs for a GitHubRepository (several Repository models may share the same GitHubRepository either by being duplicate clones of the same repository or by one being a forked repo and the other being the parent).

desktop/app/src/lib/stores/pull-request-coordinator.ts

Lines 82 to 96 in cf603e8

	return this.pullRequestStore.onPullRequestsChanged(
	(ghRepo, pullRequests) => {
	this.prCache.set(ghRepo.dbID, pullRequests)
	// find all related repos
	const matches = findRepositoriesForGitHubRepository(
	ghRepo,
	this.repositories
	)
	// emit updates for matches
	for (const match of matches) {
	fn(match, pullRequests)
	}
	}

The problem here turned out to be that this.repositories was an empty array. The repositories field is updated whenever the RepositoriesStore emits an update:

desktop/app/src/lib/stores/pull-request-coordinator.ts

Lines 50 to 60 in cf603e8

	public constructor(
	private readonly pullRequestStore: PullRequestStore,
	private readonly repositoriesStore: RepositoriesStore
	) {
	// register an update handler for the repositories store
	this.repositoriesStore.onDidUpdate(allRepositories => {
	this.repositories = allRepositories.filter(
	isRepositoryWithGitHubRepository
	)
	})
	}

And here's the crux of the issue. Since #11063 made it that much rarer for the RepositoriesStore to emit an update you would need something to happen (add/remove/change a repository) before the PullRequestCoordinator kicked into gear and started forwarding these events properly.

I've addressed this by ensuring that the list of repositories is loaded when the coordinator initiates. I've also fixed a minor bug that I happened to note while debugging this where a non-primitive object (repo.owner) was coerced into a string in order to form the equality comparison hash.

Release notes

Notes: [Fixed] Addressed an issue where pull requests could fail to update until the user switched repositories

[sergiou87]

I always love a good story, thanks for the interesting read! ☕🤓

I've noticed one extra file got added to the repo accidentally, is that right?

Other than that, and a more philosophical question/comment I added, LGTM!

[sergiou87]

Thanks for adding that comment! Looks much clearer now ❤️