anchor.diff:  class MockUsage extends Mock implements Usage {}
   
   class MockDoctor extends Mock implements Doctor {}
  +
  +class MockFlutterConfig extends Mock implements Config {}
  
positive.code: void main() {
    group('analytics', () {
      Directory tempDir;
  
      setUpAll(() {
        Cache.disableLocking();
  
negative.code:     setUp(() {
        Cache.flutterRoot = '../..';
        tempDir = fs.systemTempDirectory.createTempSync('flutter_tools_analytics_test.');
        mockFlutterConfig = MockFlutterConfig();
      });
  
      tearDown(() {
  