anchor.diff:    }
     await analyzeTests(unitTests);
     StringBuffer sb = new StringBuffer();
  -  sb.writeln("library testa_combined;\n");
  -  sb.writeln("import '${Platform.script.path}' show runTests;\n");
  +  sb.writeln("library testing.combined;\n");
  +  sb.writeln("import 'dart:io' show Directory;\n");
  +  sb.writeln("import 'package:testing/src/run_tests.dart' show runTests;\n");
     for (TestDescription description in unitTests) {
       String shortName = description.shortName.replaceAll("/", "__");
       sb.writeln(
  
positive.code:   if (!await new File.fromUri(analyzer).exists()) {
      throw "Couldn't find '$analyzerPath' in '${dartSdk.toFilePath()}'";
    }
    List<String> arguments = new List<String>.from(
        descriptions.map(
            (TestDescription desciption) => desciption.uri.toFilePath()));
    arguments
        ..add(Platform.script.resolve("../lib/reify_transformer.dart")
              .toFilePath())
        ..add(Platform.script.resolve("../bin/dartk.dart")
              .toFilePath())
        ..add(Platform.script.resolve("../bin/repl.dart")
              .toFilePath())
        ..add(Platform.script.toFilePath());
    print("Running analyzer");
    Stopwatch sw = new Stopwatch()..start();
    Process process = await Process.start(
        "./run_analyzer.sh", arguments,
        environment: {"DART_SDK": dartSdk.toFilePath()});
    process.stdin.close();
    bool hasStdout = false;
    bool hasStderr = false;
    Future stdoutFuture = process.stdout.listen((data) {
      stdout.add(data);
      hasStdout = true;
    }).asFuture();
    Future stderrFuture = process.stderr.listen((data) {
      stderr.add(data);
      hasStderr = true;
    }).asFuture();
    int exitCode = await process.exitCode;
    await stdoutFuture;
    await stderrFuture;
    if (exitCode != 0) {
      throw "Non-zero exit code ($exitCode) from analyzer.";
    }
    if (hasStdout || hasStderr) {
      throw "Non-empty output from analyzer.";
    }
    sw.stop();
  
negative.code:         "show main;");
    }
    sb.writeln("\nvoid main() {");
    sb.writeln("  Directory.current = '${testRoot.resolve('..').toFilePath()}';");
    sb.writeln("  runTests(<String, Function> {");
    for (TestDescription description in unitTests) {
      String shortName = description.shortName.replaceAll("/", "__");
  