feat(language-service): allow retreiving synchronized analyzed NgModules (#32779)

Sometimes modules retreived from the language service need to be
synchronized to the last time they were updated, and not updated
on-the-fly. This PR adds a flag to
`TypeScriptServiceHost#getAnalyzedModules` that retreives cached
analyzed NgModules rather than potentially recomputing them.

PR Close #32779

packages/language-service/src/typescript_host.ts

@@ -152,9 +152,13 @@ export class TypeScriptServiceHost implements LanguageServiceHost {
    * and templateReferences.
    * In addition to returning information about NgModules, this method plays the
    * same role as 'synchronizeHostData' in tsserver.
+   * @param ensureSynchronized whether or not the Language Service should make sure analyzedModules
+   *   are synced to the last update of the project. If false, returns the set of analyzedModules
+   *   that is already cached. This is useful if the project must not be reanalyzed, even if its
+   *   file watchers (which are disjoint from the TypeScriptServiceHost) detect an update.
    */
-  getAnalyzedModules(): NgAnalyzedModules {
+  getAnalyzedModules(ensureSynchronized = true): NgAnalyzedModules {
-    if (this.upToDate()) {
+    if (!ensureSynchronized || this.upToDate()) {
       return this.analyzedModules;
     }
 

packages/language-service/test/typescript_host_spec.ts

@@ -189,4 +189,31 @@ describe('TypeScriptServiceHost', () => {
     expect(directiveSymbol).toBeDefined();
     expect(directiveSymbol !.name).toBe('AppComponent');
   });
+
+  it('should allow for retreiving analyzedModules in synchronized mode', () => {
+    const fileName = '/app/app.component.ts';
+    const tsLSHost = new MockTypescriptHost([fileName]);
+    const tsLS = ts.createLanguageService(tsLSHost);
+    const ngLSHost = new TypeScriptServiceHost(tsLSHost, tsLS);
+
+    // Get initial state
+    const originalModules = ngLSHost.getAnalyzedModules();
+
+    // Override app.component.ts with a different component
+    tsLSHost.override(fileName, `
+      import {Component} from '@angular/core';
+
+      @Component({
+        template: '<div>Hello!</div>',
+      })
+      export class HelloComponent {}
+    `);
+    // Make sure synchronized modules match the original state
+    const syncModules = ngLSHost.getAnalyzedModules(false);
+    expect(originalModules).toEqual(syncModules);
+
+    // Now, get modules for the updated project, which should not be synchronized
+    const updatedModules = ngLSHost.getAnalyzedModules();
+    expect(updatedModules).not.toEqual(syncModules);
+  });
 });