anchor.diff:  
   import "dart:io";
   
  +const _SCRIPT_KEY = '_test_script';
  +
   void expectEquals(a, b) {
     if (a != b) {
       throw 'Expected: $a\n'
  
positive.code: void testShouldFailOutsidePath() {
    var threw = false;
    try {
      Process.runSync(platformExeName, [scriptPath], 
        includeParentEnvironment: false, environment: {'SCRIPT': 'yes'});
    } catch (_) {
      threw = true;
    }
  
    expectEquals(true, threw);
  }
  
  void testShouldSucceedWithSourcePlatformExecutable() {
  
negative.code: }
  
  void verify(String exePath, {String altPath}) {
    var env = {_SCRIPT_KEY: 'yes'};
    if (altPath != null) {
      env['PATH'] = altPath;
    }
  