test(language-service): add renamed, deleted test file (#39742)

language_service_adapter_spec was renamed to adapters_spec as part of
d39c4bbe37, but I failed to check in
adapters_spec, thereby just deleting the spec. This reintroduces it.

PR Close #39742

packages/language-service/ivy/test/legacy/adapters_spec.ts

@@ -0,0 +1,41 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import * as ts from 'typescript/lib/tsserverlibrary';
+
+import {LanguageServiceAdapter} from '../../adapters';
+
+import {MockService, setup, TEST_TEMPLATE} from './mock_host';
+
+describe('Language service adapter', () => {
+  let project: ts.server.Project;
+  let service: MockService;
+
+  beforeAll(() => {
+    const {project: _project, service: _service} = setup();
+    project = _project;
+    service = _service;
+  });
+
+  it('should mark template dirty if it has not seen the template before', () => {
+    const adapter = new LanguageServiceAdapter(project);
+    expect(adapter.isTemplateDirty(TEST_TEMPLATE)).toBeTrue();
+  });
+
+  it('should not mark template dirty if template has not changed', () => {
+    const adapter = new LanguageServiceAdapter(project);
+    adapter.readResource(TEST_TEMPLATE);
+    expect(adapter.isTemplateDirty(TEST_TEMPLATE)).toBeFalse();
+  });
+
+  it('should mark template dirty if template has changed', () => {
+    const adapter = new LanguageServiceAdapter(project);
+    service.overwrite(TEST_TEMPLATE, '<p>Hello World</p>');
+    expect(adapter.isTemplateDirty(TEST_TEMPLATE)).toBeTrue();
+  });
+});