fix(@schematics/angular): tsconfig with comments breaks universal schematic

Fixes #14371

Author: Alan Agius

packages/schematics/angular/universal/index.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 import {
+  JsonParseMode,
   Path,
   basename,
   join,
@@ -206,7 +207,7 @@ function getTsConfigOutDir(host: Tree, tsConfigPath: string): string {
     throw new SchematicsException(`Could not read ${tsConfigPath}`);
   }
   const tsConfigContent = tsConfigBuffer.toString();
-  const tsConfig = parseJson(tsConfigContent);
+  const tsConfig = parseJson(tsConfigContent, JsonParseMode.Loose);
   if (tsConfig === null || typeof tsConfig !== 'object' || Array.isArray(tsConfig) ||
     tsConfig.compilerOptions === null || typeof tsConfig.compilerOptions !== 'object' ||
     Array.isArray(tsConfig.compilerOptions)) {

packages/schematics/angular/universal/index_spec.ts

@@ -10,6 +10,7 @@ import { Schema as ApplicationOptions, Style } from '../application/schema';
 import { Schema as WorkspaceOptions } from '../workspace/schema';
 import { Schema as UniversalOptions } from './schema';
 
+// tslint:disable-next-line:no-big-function
 describe('Universal Schematic', () => {
   const schematicRunner = new SchematicTestRunner(
     '@schematics/angular',
@@ -82,7 +83,6 @@ describe('Universal Schematic', () => {
     const tree = await schematicRunner
       .runSchematicAsync('universal', workspaceUniversalOptions, appTree)
       .toPromise();
-    debugger;
     const filePath = '/tsconfig.server.json';
     expect(tree.exists(filePath)).toEqual(true);
     const contents = tree.readContent(filePath);
@@ -204,4 +204,17 @@ describe('Universal Schematic', () => {
     expect(schematicRunner.tasks[0].name).toBe('node-package');
     expect((schematicRunner.tasks[0].options as {command: string}).command).toBe('install');
   });
+
+  it(`should work when 'tsconfig.app.json' has comments`, async () => {
+    const appTsConfigPath = '/projects/bar/tsconfig.app.json';
+    const appTsConfigContent = appTree.readContent(appTsConfigPath);
+    appTree.overwrite(appTsConfigPath, '// comment in json file\n' + appTsConfigContent);
+
+    const tree = await schematicRunner.runSchematicAsync('universal', defaultOptions, appTree)
+      .toPromise();
+
+    const filePath = '/projects/bar/tsconfig.server.json';
+    expect(tree.exists(filePath)).toEqual(true);
+  });
+
 });