if n2 == n3 {
		t.Fatal("Flush didn't flush any data")
	}

	if err := w.Close(); err != nil {
		t.Fatal(err)
	}

}

// Multiple gzip files concatenated form a valid gzip file.
func TestConcat(t *testing.T) {
	var buf bytes.Buffer
	w := NewWriter(&buf)
	w.Write([]byte("hello "))
	w.Close()
	w = NewWriter(&buf)
	w.Write([]byte("world\n"))
	w.Close()

	r, err := NewReader(&buf)