anchor.diff:  void testDirectory(String name, [Iterable<StyleFix> fixes]) {
     // Locate the "test" directory. Use mirrors so that this works with the test
     // package, which loads this suite into an isolate.
  +  // TODO(rnystrom): Investigate using Isolate.resolvePackageUri instead.
     var testDir = p.dirname(currentMirrorSystem()
         .findLibrary(#dart_style.test.utils)
         .uri
  
positive.code:       .toFilePath());
    var scriptPath = p.normalize(p.join(p.dirname(testDir), script));
  
    var compileResult = await Process.run(
        dart2Native, [scriptPath, '--output', executable]);
  
    if (compileResult.exitCode != 0) {
      fail('Could not compile $scriptName to a snapshot (exit code '
  
negative.code:     fail('Must call createFormatterExecutable() before running commands.');
    }
  
    return TestProcess.start(
        Platform.resolvedExecutable, [_formatterExecutablePath, ...?args],
        workingDirectory: d.sandbox);
  }
  
  