Optimization Goals:
The primary goals of this optimization are to dramatically reduce the execution time of the language-service test suite and stabilize the mock file system infrastructure. Previously, the suite suffered from significant overhead due to recreating the `MockFileSystem`, `MockServerHost`, and TypeScript `ProjectService` for every single test block, leading to redundant parsing operations, slow test initialization, and reduced spec performance.
How the Goals Were Achieved:
1. **Mock File System Optimizations (Shared State)**:
- Evaluated that standard test files (e.g., TS/Angular lib definitions) are immutable across tests.
- Introduced and utilized `lockMockFileSystem()` to initialize the mock `FileSystem` with `loadStandardTestFiles()` only once per test suite run rather than repeatedly per test.
- Refactored `LanguageServiceTestEnv.setup()` to reuse the singleton file system, completely skipping redundant module loading by eagerly flagging `fsInitialized = true`.
2. **Language Service Test Environment Enhancements (TypeScript Project Reuse)**:
- Implemented partial configuration reloads in the `Project` class via the `update()` method, removing the need to tear down and rebuild the entire `MockServerHost` and TypeScript `ProjectService` from scratch when minimal file changes (like HTML templates or local TS edits) are made dynamically by a test.
- Applied `projectService.reloadProjects()` and `scriptInfo.reloadFromFile()` to synchronously push mock file tree invalidations to the active TS program, skipping expensive environment initialization and saving considerable latency across tests.
- Added `projectName` identifiers inside complex isolate tests (e.g. module alias aliasing) so custom environment injections can sandbox safely without invalidating the global default environment cache.
3. **Test Suite Unification**:
- Flattened fragmented test groups (`grp1`, `grp3`, `grp4`) into a cohesive single directory at `packages/language-service/test/`. This simplifies execution config, improves test runner concurrency, and unifies local development targeting.
- Cleaned out broken inline debug logging and unneeded config reloading loops.
4. **Maintaining Test Isolation**:
- **Explicit TypeScript Configuration**: While the underlying `MockFileSystem` ("disk") is aggressively reused across tests, the TypeScript `ProjectService` and its execution environment are entirely recreated for every test run to ensure isolated ASTs and module resolution caches.
- **Strict tsconfig.json Files Array**: When a project is initialized, it explicitly defines its boundary using the strict `files: [ ... ]` array in `tsconfig.json`. This ensures that any leftover files physically on the mock disk from an older test run are completely invisible to the TS Compiler.
- **Namespace Sandboxing**: For tests doing custom modifications (e.g., overriding module resolution paths), they utilize localized `projectName` arguments (like `"test_alias_completions"`) to configure sandboxed working directories.
This feature enables synchronized editing of opening and closing HTML tag pairs
in Angular inline templates. When the cursor is on an element tag name, editing
it will automatically update the corresponding tag.
Implementation:
- Add getLinkedEditingRangeAtPosition method to NgLanguageService interface
- Implement linked editing range detection for opening and closing tags
- Handle edge cases: self-closing elements, void elements, cursor detection
- Export through ts_plugin wrapper to override TypeScript JSX-only implementation
- For external HTML templates, VS Code built-in HTML support handles linked editing
Andrew Scott