anchor.diff:        .then((TempDir value) {
           tmpDir = value;
   
  -        absolutePath = pathos.join(tmpDir.path, fileRelativePath);
  +        absolutePath = pathos.join(tmpDir.path, entityRelativePath);
   
  -        if(existingEntity != null) {
  -          switch(existingEntity) {
  +        if(existingEntityType != null) {
  +          switch(existingEntityType) {
               case FileSystemEntityType.FILE:
                 var existing = new File(absolutePath);
                 return existing.writeAsString('existing content');
  
positive.code:               if(existingEntity == null) {
                  // ignore existingEntity
                  test('no parent dir; create parent: $createParent; '
                      'overwrite existing: $overwriteExisting; will $resultStr', () {
                    return _testFileFromString(createParent, overwriteExisting,
                        parentDirExists, existingEntity, success);
                  });
                }
              } else {
                var existingString = (existingEntity == null) ?
                    'no existing entity' : 'existing $existingEntity';
                test('parent exists; $existingString; create parent: $createParent; '
                    'overwrite existing: $overwriteExisting; will $resultStr', () {
                  return _testFileFromString(createParent, overwriteExisting,
                      parentDirExists, existingEntity, success);
                });
              }
  
negative.code:   });
  }
  
  Future _testEntityPopulator(FileSystemEntityType entityType,
                              dynamic entityContent, bool createParent,
                              bool overwriteExisting, bool parentDirExists,
                              FileSystemEntityType existingEntityType,
                              bool expectedSuccess) {
  
    const entityName = 'targetEntityName';
  
    assert(parentDirExists == true || existingEntityType == null);
  
    final entityRelativePath = parentDirExists ?
        entityName : pathos.join('parentDir', entityName);
  
  
    TempDir tmpDir;
  