jagged i8 test

def test_jagged_i8(tmp_path):
    filename = join(str(tmp_path), "example.root")

    a = awkward.fromiter([[0],
                          [1, 2],
                          [10, 11, 12]])

    with uproot.recreate(filename, compression=None) as f:
        f["t"] = uproot.newtree({"branch": uproot.newbranch(numpy.dtype(">i8"), dependence="n")})
        f["t"].extend({"branch": a, "n": [1, 2, 3]})

    ROOT.gInterpreter.Declare("""
        void readnewbasket(Long64_t* arr, char* filename) {
            TFile *f = new TFile("jaggedint.root");
            Long64_t x;
            Int_t num;
            Int_t last_num = 0;
            auto tree = f->Get<TTree>("t");
            auto n = tree->GetBranch("n");
            auto branch = tree->GetBranch("branch");
            n->SetAddress(&num);
            branch->SetAddress(&x);
            for (int i=0; i<tree->GetEntries(); i++) {
                tree->GetEvent(i);
                for (int j=0; j<num; j++) {
                    *(arr + (i*last_num) + j) = x+j;
                }
                last_num = num;
            }
        }""")

    testa = awkward.fromiter([[0], [0, 0], [0, 0, 0]])
    ROOT.readnewbasket(testa, filename)
    for i in range(3):
        assert (a[i] == testa[i])