#include <bits/stdc++.h>

#define endl "\n"
using namespace std;

typedef pair<int,int> PII;
const int N = 2e5 + 5, MOD = 1e9 + 7;
int n;
int a[N];

int ksm(int a,int b){
    int r = 1;
    while (b){
        if (b & 1) r = r * a % MOD;
        a = a * a % MOD;
        b >>= 1;
    }
    return r;
}

void solve(){
    cin >> n;
    bool f = 0;
    for(int i = 1; i <= n; i++){
        cin >> a[i];
        if(i != 1 && a[i] == 0) f = 1;
    }
    if(a[0] != 0 || a[n] != n - 1 || f){
        cout << 0 << endl;
        return;
    }
    int cnt = 0;
    for(int i = 2; i <= n; i++){
        if(a[i] != a[i - 1]) cnt++;
    }
    cout << ksm(2, cnt) << endl;
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int _ = 1;
    cin >> _;
    while(_--){
        solve();
    }
}