#include <bits/stdc++.h>

using namespace std;

int main() {
    int tt;
    cin >> tt;
    while (tt--) {
        int n;
        cin >> n;

        vector <int> deg(n + 1);
        set <pair <int, int>> st;
        for (int i = 1; i <= n; i++) {
            cin >> deg[i];
            if (deg[i] > 0)
                st.insert({deg[i], i});
        }

        vector < pair <int, int> > edges;
        while (!st.empty()) {
            auto last = --st.end();
            auto prev = --(--st.end());
            edges.emplace_back(last->second, prev->second);
            pair <int, int> p1 = *last, p2 = *prev;
            st.erase(last);
            st.erase(prev);
            p1.first--;
            p2.first--;
            if (p1.first > 0)
                st.insert(p1);
            if (p2.first > 0)
                st.insert(p2);

        }

        cout << edges.size() << endl;
        for (int i = 0; i < edges.size(); i++) {
            cout << edges[i].first << " " << edges[i].second << endl;
        }
    }
}