test(language-service): recognize inputs/ouputs declared in decorator (#34875)

This commit adds a regression test to check that the language service
recognizes inputs and outputs declared in a directive decorator.

See #34874.

PR Close #34875

packages/language-service/test/diagnostics_spec.ts

@@ -646,6 +646,14 @@ describe('diagnostics', () => {
     expect(ngDiags).toEqual([]);
   });
 
+  // Issue https://github.com/angular/angular/issues/34874
+  it('should recognize inputs and outputs listed inside directive decorators', () => {
+    mockHost.override(
+        TEST_TEMPLATE, `<div hint-model [hint]="title" (hintChange)="myClick($event)"></div>`);
+    const ngDiags = ngLS.getSemanticDiagnostics(TEST_TEMPLATE);
+    expect(ngDiags).toEqual([]);
+  });
+
   it('should be able to resolve modules using baseUrl', () => {
     mockHost.override(APP_COMPONENT, `
       import { Component } from '@angular/core';

packages/language-service/test/project/app/main.ts

@@ -34,6 +34,7 @@ import * as ParsingCases from './parsing-cases';
     ParsingCases.CaseMissingClosing,
     ParsingCases.CaseUnknown,
     ParsingCases.EmptyInterpolation,
+    ParsingCases.HintModel,
     ParsingCases.NoValueAttribute,
     ParsingCases.NumberModel,
     ParsingCases.Pipes,

packages/language-service/test/project/app/parsing-cases.ts

@@ -60,6 +60,16 @@ export class NumberModel {
   @Output('outputAlias') modelChange: EventEmitter<number> = new EventEmitter();
 }
 
+@Directive({
+  selector: '[hint-model]',
+  inputs: ['hint'],
+  outputs: ['hintChange'],
+})
+export class HintModel {
+  hint: string = 'hint';
+  hintChange: EventEmitter<string> = new EventEmitter();
+}
+
 interface Person {
   name: string;
   age: number;