anchor.diff:  
   import 'package:file/file.dart';
   import 'package:file/memory.dart';
  +import 'package:flutter_tools/src/cache.dart';
   import 'package:flutter_tools/src/base/context.dart';
   import 'package:flutter_tools/src/base/io.dart';
   import 'package:flutter_tools/src/base/platform.dart';
  
positive.code:         error = 'test failed unexpectedly: $thrownError';
        });
        time.elapse(const Duration(milliseconds: 500));
        expect(processMock.lastPubCache, endsWith('flutter/.pub-cache'));
        expect(error, isNull);
      });
    }, overrides: <Type, Generator>{
  
negative.code:     final MockProcessManager processMock = context.getVariable(ProcessManager);
  
      new FakeAsync().run((FakeAsync time) {
        MockDirectory.findCache = true;
        expect(processMock.lastPubEnvironmment, isNull);
        expect(processMock.lastPubCache, isNull);
        pubGet(context: PubContext.flutterTests, checkLastModified: false).then((Null value) {
  