#include <bits/stdc++.h>
using namespace std;
int main() {
    const int mod = 1000000007;
    int inv2 = (mod + 1) / 2;
    int inv4 = (mod + 1) / 4;
    int n, test;
    cin >> test;
    while (test--) {
        int n;
        cin >> n;
        vector<int> a(n);
        for (int i = 0; i < n; ++i) {
            cin >> a[i];
        }
        int ans = a[0] / 2;
        for (int i = 1; i < n; ++i) {
            ans = (ans + (a[i] - a[i - 1]) / 2ll * inv2) % mod;
        }
        printf("%d\n", ans);
    }
}