anchor.diff:  
   import 'package:analyzer/error/error.dart';
   import 'package:analyzer/file_system/physical_file_system.dart';
  -import 'package:path/path.dart';
   import 'package:test/test.dart';
   import 'package:test_reflective_loader/test_reflective_loader.dart';
   
  
positive.code:     //
      // Validate that the generator has been run.
      //
      if (pathContext.style != Style.windows) {
        String actualContent = PhysicalResourceProvider.INSTANCE
            .getFile(computeOutputPath())
            .readAsStringSync();
  
        StringBuffer sink = StringBuffer();
        DocumentationGenerator generator = DocumentationGenerator();
        generator.writeDocumentation(sink);
        String expectedContent = sink.toString();
  
        if (actualContent != expectedContent) {
          fail('The diagnostic documentation needs to be regenerated.\n'
              'Please run tool/diagnostics/generate.dart.');
        }
      }
    }
  
  
negative.code: class VerifyDiagnosticsTest {
    @TestTimeout(Timeout.factor(4))
    test_diagnostics() async {
      //
      // Validate that the input to the generator is correct.
      //
  