Support VS Code testing API

[yoshuawuyts]

The Java plugin for VS Code comes with a built-in test explorer panel. This panel shows all tests in the project, and allows running the full suite (link).

Rust Analyzer currently only provides a way to run a single unit test. This opens the console, and runs it there. There is no way to run multiple tests, or browse the tests. Making progress towards this would probably help carry the IDE experience forward.

Example

Java test explorer workflow example (source)

[yoshuawuyts]

Oh actually just now realizing there are a collection of plugins available for this:

• vscode test explorer
• vscode rust test adapter

Heh, that's nice. I wonder if a tighter integration story would be possible / desirable? Maybe there are things on the lang server side that could be picked up?

[matklad]

Rust Analyzer currently only provides a way to run a single unit test.

You can also run a module with tests. But yeah, having something like test explorer above would be nice and is definitely in scope. The biggest catch here is that there's no LSP protocol for this at the moment.

[godcodehunter]

Ok, looks funny, I'll do it.

[xsoheilalizadeh]

Related microsoft/vscode#107467

[yoshuawuyts]

The VS Code Test UI has stabilized as part of the July 2021 update! There's a guide available here on how to write extensions for this.

Integrating with this would be fantastic!

Screenshots

[matklad]

https://code.visualstudio.com/api/extension-guides/testing

We might want to support that.

The way I understand it, what VS Code wants is a global view of a hierarchy of all the tests in a project. There are two potential sources for such view:

• statically discovered tests (eg, re-run cargo test -- --list on every change, or use symbol index to list every #[test] function)
• external sources -- display a result of a test run

I don't think we can support the first case correctly: in the limit, it is a global view of all the tests, and to maintain that we'd have to do O(N) work on every change worst-case. Displaying a hierarchy of tests also feels like it duplicates other navigation functionality.

So I think we should do the following:

• on the server side, provide the API to fetch project model, such that the vscode can draw one node per cargo package/target
• on the client side, change our test runners to optionally pass in the --message-format json flag, and to populate nodes bellow cargo target with test results.

[godcodehunter]

Yep, I am working on this. Now I finished the presentation and api. Today I hope to move on to creating observable test data structure.

https://code.visualstudio.com/api/extension-guides/testing

We might want to support that.

The way I understand it, what VS Code wants is a global view of a hierarchy of all the tests in a project. There are two potential sources for such view:

• statically discovered tests (eg, re-run cargo test -- --list on every change, or use symbol index to list every #[test] function)
• external sources -- display a result of a test run

I don't think we can support the first case correctly: in the limit, it is a global view of all the tests, and to maintain that we'd have to do O(N) work on every change worst-case. Displaying a hierarchy of tests also feels like it duplicates other navigation functionality.

So I think we should do the following:

• on the server side, provide the API to fetch project model, such that the vscode can draw one node per cargo package/target
• on the client side, change our test runners to optionally pass in the --message-format json flag, and to populate nodes bellow cargo target with test results.