This requires a bit of a restructuring of `ToolchainRegistry` because calling `scanForToolchain` on `self` is a suspension point. Instead, we need to implement the entire toolchain discovery in the initializer itself, which really isn’t that bad anyway.
This allows us to make the `SourceKitLSP.run` function synchronous again.
Fixes#1023
rdar://120976054
Global state is never a good thing and we needed to modify it in tests. The design becomes a lot cleaner if we explicitly pass the toolchain registry around.
The new approach has a few advantages over the olde TIBS-based approach:
1. The source file being tested is defined within the test case itself and not in a separate file, which makes it easier to understand the test case since the auxiliaury file doesn’t need to be opened. Finding it inside `Sources/SKTestSupport/INPUTS` is already hard for people that are not familiar with the codebase.
2. The build setup is significantly simpler since it doesn’t rely on `ninja`. It is thus easier to understand what is run during the test.
3. We can use the emoji location markers to refer to test locations, like we do for files that are opened using `TestSourceKitLSPClient.openDocument`.
This commit only migrates call hierarchy testing to the new design. If we like it, I’ll migrate the other test workspaces as well.
Sending the `InitializeRequest` was always unnecessarily verbose. If we automatically initialize the server when creating the test client, the code becomes sufficiently concise that we can set up the client + server in the test method itself and no longer need the `setUp` methods, making the tests easier to read.
Instead of listening for document updates sent from `sourcekitd` and sending a `PublishDiagnosticsNotification` based on the `sourcekitd` notification, wait for a little while and then execute an internal `DocumentDiagnosticsRequest` to load diagnostics and send them to the client.
This has two advantages:
- It unifies the two diagnostic implementations
- It removes the need to keep track of semantic diagnostics in `SwiftLanguageServer`
- It gets us one step closed to opening and editing documents in `syntactic_only` mode. The only thing that is left now are semantic tokens.
