t.Errorf("ReadAt(%d, %d) = %q; want %q", i, j, buf, all[i:i+j])
			}
		}
	}
}

// fakeHash32 is a dummy Hash32 that always returns 0.
type fakeHash32 struct {
	hash.Hash32
}

func (fakeHash32) Write(p []byte) (int, error) { return len(p), nil }
func (fakeHash32) Sum32() uint32               { return 0 }

func TestZip64(t *testing.T) {
	if testing.Short() {