fix: check project files update more aggressively before assigning service (#2518)

#2516

Most of the time, the didOpen request is earlier than the watcher event. So if the file doesn't exist in the GlobalSnapshotManager we manually invoke the project file update check. This won't cause 2 project files check because if the file already is a project file we won't check project files.

Author: jasonlyu123

packages/language-server/src/plugins/typescript/service.ts

@@ -40,7 +40,7 @@ export interface LanguageServiceContainer {
     deleteSnapshot(filePath: string): void;
     invalidateModuleCache(filePath: string[]): void;
     scheduleProjectFileUpdate(watcherNewFiles: string[]): void;
-    ensureProjectFileUpdates(): void;
+    ensureProjectFileUpdates(newFile?: string): void;
     updateTsOrJsFile(fileName: string, changes?: TextDocumentContentChangeEvent[]): void;
     /**
      * Checks if a file is present in the project.
@@ -225,7 +225,7 @@ export async function getService(
         service: LanguageServiceContainer,
         triedTsConfig: Set<string>
     ): Promise<LanguageServiceContainer | undefined> {
-        service.ensureProjectFileUpdates();
+        service.ensureProjectFileUpdates(path);
         if (service.snapshotManager.isProjectFile(path)) {
             return service;
         }
@@ -648,9 +648,23 @@ async function createLanguageService(
         }
     }
 
-    function ensureProjectFileUpdates(): void {
+    function ensureProjectFileUpdates(newFile?: string): void {
         const info = parsedTsConfigInfo.get(tsconfigPath);
-        if (!info || !info.pendingProjectFileUpdate) {
+        if (!info) {
+            return;
+        }
+
+        if (
+            newFile &&
+            !info.pendingProjectFileUpdate &&
+            // no global snapshots yet when initial load pending
+            !snapshotManager.isProjectFile(newFile) &&
+            !docContext.globalSnapshotsManager.get(newFile)
+        ) {
+            scheduleProjectFileUpdate([newFile]);
+        }
+
+        if (!info.pendingProjectFileUpdate) {
             return;
         }
         const projectFileCountBefore = snapshotManager.getProjectFileNames().length;

packages/language-server/test/plugins/typescript/service.test.ts

@@ -657,6 +657,33 @@ describe('service', () => {
         assert.deepStrictEqual(findError(ls2), undefined);
     });
 
+    it('assigns newly created files to the right service before the watcher trigger', async () => {
+        const dirPath = getRandomVirtualDirPath(testDir);
+        const { virtualSystem, lsDocumentContext, rootUris } = setup();
+
+        const tsconfigPath = path.join(dirPath, 'tsconfig.json');
+        virtualSystem.writeFile(
+            tsconfigPath,
+            JSON.stringify({
+                compilerOptions: {}
+            })
+        );
+
+        const svelteFilePath = path.join(dirPath, 'random.svelte');
+
+        virtualSystem.writeFile(svelteFilePath, '');
+
+        const ls = await getService(svelteFilePath, rootUris, lsDocumentContext);
+
+        assert.equal(normalizePath(ls.tsconfigPath), normalizePath(tsconfigPath));
+
+        const svelteFilePath2 = path.join(dirPath, 'random2.svelte');
+        virtualSystem.writeFile(svelteFilePath2, '');
+
+        const ls2 = await getService(svelteFilePath2, rootUris, lsDocumentContext);
+        assert.equal(normalizePath(ls2.tsconfigPath), normalizePath(tsconfigPath));
+    });
+
     function getSemanticDiagnosticsMessages(ls: LanguageServiceContainer, filePath: string) {
         return ls
             .getService()