[outline view] merge custom DocumentSymbols with system Features

[connectdotz]

mocha/jest tests use unamed functions extensively, such as the describe(), it(). These functions appeared in the outline view as <function>, which obviously not very helpful. We implemented a custom DocumentSymbolProvider Jest to provide the test names for these functions:

According to the document, when multiple DocumentSymbolProviders are registered, vscode will merge their results. However, judging from the output above, the symbols didn't seem to be "merged" but "appended". Ideally, we would like to have just 1 tree Typescript and JavaScript Language Features, replace the unnamed <function> while leaving everything else within intact. Not sure if this is a bug or maybe there is another way to contribute to the outline system provider?

[jrieken]

Well, both trees are merged but only at the level of the root node 🤓 This is different when outline information is shown as flat list - as in quick outline. The challenge is how to merge two trees from which you don't know much, esp. when ranges don't strictly contain each other but overlap.

[connectdotz]

Yes, it is a hard problem given there might be many different contributors to the outline view... IMHO, the simplest solution might be to outsource the merge logic to the contributor, such as a new event type, let's say onDocumentSymbolsChanged, to give external extensions opportunity to modify/merge the source documentSymbols upon change...

[jrieken]

to give external extensions opportunity to modify/merge the source documentSymbols upon change...

And how should they do it? Isn't it the same problem?

[connectdotz]

each extension might act differently based on their source of symbols. For us, since we parse the test file ourselves, we do have each function block's positions, I would assume there is a way to match our symbols with the system symbols by their ranges/positions.

Granted not all providers can, or desire, to do such merge, but for those that could and desire, this seems like a relatively simple hook outline system could allow...

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[WA9ACE]

Is there no way to disable one of the multiple document symbol providers at least from rendering in the outline view? The duplication of information is noisy for example in this case.