anchor.diff:              output: isNot(contains('PUB_ALLOW_PRERELEASE_SDK')));
         });
   
  -      test("patch SDK versions to match", () async {
  +      test("patch SDK versions differ", () async {
           await d.dir(appPath, [
             await d.pubspec({
               'name': 'myapp',
  
positive.code:             output: isNot(contains('PUB_ALLOW_PRERELEASE_SDK')));
        });
  
        test("no build release constraints", () async {
          await d.dir(appPath, [
            await d.pubspec({
              'name': 'myapp',
  
negative.code:                 contains('<=1.2.3-dev.1.0'), contains('myapp')));
        });
  
        test("lower bound is pre-release but doesn't match SDK", () async {
          await d.dir(appPath, [
            await d.pubspec({
              'name': 'myapp',
  