type fakeMounter … // IsLikelyNotMountPoint overrides mount.FakeMounter.IsLikelyNotMountPoint for our use. func (f *fakeMounter) IsLikelyNotMountPoint(file string) (bool, error) { … } func TestRemoveAllOneFilesystem(t *testing.T) { … } func TestRemoveDirsOneFilesystem(t *testing.T) { … }