#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>    // 包含 tree、gp_hash_table、cc_hash_table
#include <ext/pb_ds/priority_queue.hpp> // 引入后使用 STL 的堆需要 std::
#include <ext/rope>
using namespace __gnu_pbds;
using namespace __gnu_cxx;
using namespace std;
template<class key, class val = null_type, class cmp = less<>>
using rb_tree = tree<key, val, cmp, rb_tree_tag, tree_order_statistics_node_update>;
template<class key, class cmp = less<>>
using pairing_heap = __gnu_pbds::priority_queue<key, cmp>;
typedef long long ll;
#define int long long
template<class T> void print_debug(const T & v) { cerr << v; }
template<class T, class ... A> void print_debug(const T & v, const A & ... a) { cerr << v << ", ", print_debug(a...); }
#define debug(...) (cerr << "[" << #__VA_ARGS__ << "] = [", print_debug(__VA_ARGS__), cerr << "]\n")
mt19937_64 rd(time(0));

const int mod = 1e9 + 7;

auto binpow = [](int a, int b, int res = 1) {
    for (a %= mod; b; b >>= 1, (a *= a) %= mod) {
        if (b & 1) (res *= a) %= mod;
    }
    return res;
};

vector<int> inv, fact, invfact;

auto init_inv = [](int n) {
    inv = fact = invfact = vector<int>(n + 1, 1);   // 注意 0 的 inv 无意义
    for (int i = 2; i <= n; i++) {  // 注意从 2 开始
        (inv[i] = (mod - mod / i) * inv[mod % i]) %= mod;
        (fact[i] = fact[i - 1] * i) %= mod, (invfact[i] = invfact[i - 1] * inv[i]) %= mod;
    }
};

auto C = [](int n, int m) -> int {
    return m > n || n < 0 || m < 0 ? 0 : fact[n] * invfact[m] % mod * invfact[n - m] % mod;
};
auto P = [](int n, int m) -> int {
    return m > n || n < 0 || m < 0 ? 0 : fact[n] * invfact[n - m] % mod;
};
auto Lucas = [](auto && self, int n, int m) -> int {
        return m == 0 ? 1 : C(n % mod, m % mod) * self(self, n / mod, m / mod) % mod;
};

void QAQ() {
    int n, ans = 1;
    cin >> n;

    vector<int> a(n + 1);

    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    if (a[1] != 0) return cout << "0\n", void();
    if (*max_element(a.begin() + 1, a.end()) != n - 1) return cout << "0\n", void();

    for (int i = 2; i <= n; i++) {
        if (a[i - 1] < a[i]) {
            (ans *= 2) %= mod;
        } else if (a[i] == a[i - 1]) {
            (ans *= max<int>(0, a[i] + 1 - (i - 1))) %= mod;
        } else return cout << "0\n", void();
    }

    cout << ans << "\n";
}

signed main() {
    cin.tie(0) -> sync_with_stdio(0);
    cout << fixed << setprecision(12);
    int t = 1;
    cin >> t;

    while (t--) {
        QAQ();
    }
}