match plist indentation with xcode format

Summary:
xcode has its own way of indentation of the plist.

fixes #11668
Closes https://github.com/facebook/react-native/pull/11670

Differential Revision: D4410865

fbshipit-source-id: 8c65e7719d228b07f58b1ccb86b369e319067f02

local-cli/link/__tests__/ios/writePlist.spec.js

@@ -0,0 +1,52 @@
+'use strict';
+
+jest.autoMockOff();
+jest.mock('fs');
+
+let plistPath = null;
+jest.mock('../../ios/getPlistPath', () => () => plistPath);
+
+const { readFileSync } = require.requireActual('fs')
+const fs = require('fs');
+
+const xcode = require('xcode');
+const path = require('path');
+const writePlist = require('../../ios/writePlist');
+
+const projectPath = path.join(__dirname, '../../__fixtures__/project.pbxproj');
+const infoPlistPath = path.join(__dirname, '../../__fixtures__/Info.plist');
+
+fs.__setMockFilesystem({
+  'Basic': {
+    'project.pbxproj': readFileSync(projectPath).toString(),
+  }
+});
+
+const project = xcode.project('/Basic/project.pbxproj');
+
+const plist = {
+  CFBundleDevelopmentRegion: 'en',
+  UISupportedInterfaceOrientations: [
+    'UIInterfaceOrientationPortrait'
+  ]
+};
+
+describe('ios::writePlist', () => {
+  beforeEach(() => {
+    project.parseSync();
+    fs.writeFileSync.mockReset();
+  });
+
+  it('should write a `.plist` file', () => {
+    plistPath = '/Basic/Info.plist';
+    const result = writePlist(project, '/', plist);
+    const infoPlist = readFileSync(infoPlistPath).toString();
+    expect(fs.writeFileSync).toHaveBeenCalledWith(plistPath, infoPlist);
+  });
+
+  it('when plistPath is null it should return null', () => {
+    plistPath = null;
+    expect(writePlist(project, '/', plist)).toBeNull();
+    expect(fs.writeFileSync).not.toHaveBeenCalled();
+  });
+});