anchor.diff:      expect(value.dependencies, isEmpty);
       expect(value.devDependencies, isEmpty);
       expect(value.dependencyOverrides, isEmpty);
  +    expect(value.repository, Uri.parse('https://github.com/example/repo'));
  +    expect(value.issueTracker,
  +        Uri.parse('https://github.com/example/repo/issues'));
     });
   
     test('environment values can be null', () {
  
positive.code:     expect(value.devDependencies, isEmpty);
      expect(value.dependencyOverrides, isEmpty);
      expect(value.flutter, isNull);
    });
  
    test('all fields set', () {
  
negative.code:       'environment': {'sdk': sdkConstraint.toString()},
        'description': 'description',
        'homepage': 'homepage',
        'documentation': 'documentation',
        'repository': 'https://github.com/example/repo',
        'issue_tracker': 'https://github.com/example/repo/issues',
      });
      expect(value.name, 'sample');
      expect(value.version, version);
  