code: func TmpDir(t TestReporter, dir string) string {
  	name, err := afero.TempDir(appFs, dir, "dir")
  	if err != nil {
  		t.Error("Failed to create the tmpDir: "+name, err)
  	}
  
  	Files = append(Files, name)
  	return name
  }
docs: /*
  TmpDir Creates a tmp directory for us to use.
  */