anchor.diff:          r'/foo/b\b.dart',
           r'/foo/c\ c.dart',
         ]));
  -    }, overrides: <Type, Generator>{ FileSystem: () => fs});
  +    }, overrides: <Type, Generator>{ FileSystem: () => fs });
     });
   }
  
positive.code:         '/foo/b.dart',
          '/foo/c.dart',
        ]));
      }, overrides: <Type, Generator>{ FileSystem: () => fs});
  
      testUsingContext('returns files with spaces and backslashes', () async {
        await fs.file('a.d').writeAsString(r'snapshot.d: /foo/a\ a.dart /foo/b\\b.dart /foo/c\\ c.dart');
  
negative.code:           () => new Checksum.fromFiles(BuildMode.debug, TargetPlatform.ios, <String>['a.dart', 'b.dart'].toSet()),
            throwsA(anything),
          );
        }, overrides: <Type, Generator>{ FileSystem: () => fs });
  
        testUsingContext('throws if any build mode is null', () async {
          await fs.file('a.dart').create();
  