}

		// It should wind up a double of the original data.
		if strings.Repeat(string(data), 2) != string(data2) {
			t.Fatalf("data mismatch: %s != %s", string(data), string(data2))
		}
	})
	t.Run("NotRegular", func(t *testing.T) {
		t.Run("BothPipes", func(t *testing.T) {
			hook := hookCopyFileRange(t)

			pr1, pw1, err := Pipe()
			if err != nil {
				t.Fatal(err)
			}
			defer pr1.Close()