`SwiftPMBuildSystem.testFiles()` returned all source files in the package, including files of package dependencies. This caused us to index those files for tests in the syntactic test index, which we should not.
Make `SwiftPMBuildSystem.testFiles` only return files from the root package.
Also add test infrastructure to be able to test cross-package functionality.
rdar://126965614
When the client sends us `workspace/didChangeWatchedFiles` notification of an updated `.swift` file, we should refresh the other open files in that module since they might be referencing functions from that updated file.
If a `.swiftmodule` file has been updated, we refresh all the files within the package since they might import that module. Technically, we would only need to refresh files that are in module that are downstream of the updated module but we don’t currently have that information easily available from SwiftPM. Also, usually, if the client has a file from a low-level module open, he’ll be working on that module which means that such an optimization won’t help. The real solution here is to wait for us to finish preparation (which we would exactly know when it finishes since sourcekit-lsp would schedule it) but for that we need to implement background preparation.
Fixes#620Fixes#1116
rdar://99329579
rdar://123971779
Rename all the classes that write files to disk to create a test project that we can open in sourcekit-lsp to end with `TestProject`. This is better than the old `Workspace` suffix because it avoids ambiguities with the `Workspace` type inside sourcekit-lsp.
- IndexedSingleSwiftFileWorkspace -> IndexedSingleSwiftFileTestProject
- MultiFileTestWorkspace -> MultiFileTestProject
- SwiftPMTestWorkspace -> SwiftPMTestProject
