  require.Error(t, err)  require.Equal(t, true, errors.Is(err, errNotFound))   _, err = cc.ChecksumWildcard(context.TODO(), ref, "y0", true)  require.Error(t, err)  require.Equal(t, true, errors.Is(err, errNotFound))   dgst, err = cc.Checksum(context.TODO(), ref, "sym", false)  require.NoError(t, err)  require.Equal(t, expectedSym, dgst)   dgst, err = cc.Checksum(context.TODO(), ref, "foo/ghi", false)  require.NoError(t, err)  require.Equal(t, expectedSym, dgst)   err = ref.Release(context.TODO())  require.NoError(t, err) }  func TestChecksum