preferences: fix duplicated call to FoldersPreferencesProvider

[paul-marechal]

Properly inhibit preference providers when they shouldn't apply during resolution.

How to test

Debug the following method:

theia/packages/core/src/browser/preferences/preference-service.ts

Lines 563 to 581 in 7971705

	protected doResolve<T>(preferenceName: string, defaultValue?: T, resourceUri?: string): PreferenceResolveResult<T> {
	const result: PreferenceResolveResult<T> = {};
	for (const scope of PreferenceScope.getScopes()) {
	if (this.schema.isValidInScope(preferenceName, scope)) {
	const provider = this.getProvider(scope);
	if (provider?.canHandleScope(scope)) {
	const { configUri, value } = provider.resolve<T>(preferenceName, resourceUri);
	if (value !== undefined) {
	result.configUri = configUri;
	result.value = PreferenceProvider.merge(result.value as any, value as any) as any;
	}
	}
	}
	}
	return {
	configUri: result.configUri,
	value: result.value !== undefined ? deepFreeze(result.value) : defaultValue
	};
	}

Make sure it doesn't end up calling the same provider twice.

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

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[paul-marechal]

@AlexandraBuzila can you take over fixing the test suite? This is what you forgot to do the first time you introduced the change to merge configs together: The tests must be updated accordingly.

[AlexandraBuzila]

Hi @paul-marechal! Yes, I can have a look at the tests.
Just to clarify, this is about reapplying the changes from #12126 and fixing the tests, correct? The tests on this branch are green on my end.

Unrelated question: I was able to run the tests on your branch locally, but after reapplying my changes I keep getting an NSFW service error and the tests are pending.

root ERROR [nsfw-watcher: 49885] NSFW service error on "/tmp/theia-test-config-dir202327-49736-3feycm.32qeo": [Error: Service shutdown: root path changed (renamed or deleted)]

I had this happen in the past as well, but it resolved itself after a few retries. Now I can't get them to work at all. Do you maybe know if there's a trick to fix this? I'm running on linux.

[paul-marechal]

I think the launch test suite is currently being skipped. edit: They're not.

We're indeed missing the the changes from #12126

[AlexandraBuzila]

Hi @paul-marechal
I added back the changes from #12126 and fixed the tests in #12275

The target for that PR is this branch, as your changes are needed as well for the tests to work.

[vince-fugnitto]

The changes look good to me 👍

• confirmed that preferences at different scopes are properly applied
• confirmed that the additional unit-tests pass successfully
• confirmed that merged configurations work well (#8987)

[vince-fugnitto]

LGTM 👍