///by Saton.
#include<bits/stdc++.h>
#define PI acos(-1)
#define fi first
#define se second 
#define sz(a) ((int)a.size())
#define all(a) a.begin(), a.end()
#define LL long long
#define ll __int128
#define DD double double
#define LD long double
#define rep(i,a,b) for(LL i = (a);i <= (b);i ++)
#define lep(i,a,b) for(LL i = (a);i >= (b);i --)
#define FLUSH fflush(stdout)
using namespace std;
const int N = 2e5 + 10,mod =  1e9+7,P = 131;
const LL inf = 1e9+10,INF = 1e18+10;
typedef pair<int,int> PII;
typedef pair<LL,int> PLI;
typedef pair<LL,LL> PLL;
LL n,m,k;

void solve() {
    cin >> n;
    vector<LL> a(n+1);
    rep(i,1,n) cin >> a[i];
    
    if(a[1]!=0 || a[n]!=n-1) {
        cout << 0 << '\n';
        return;
    }
    rep(i,1,n-1) if(a[i]>n-1 || a[i]>a[i+1]) {
        cout << 0 << '\n';
        return;
    }
    
    LL ans = 1;
    map<int,int> cnt;
    rep(i,1,n-1) {
        if(i!=1) cnt[a[i]] ++;
        if(a[i]!=a[i+1]) ans = ans*2%mod;
    }
    for(auto [u,v] : cnt) if(u<v) {
        cout << 0 << '\n';
        return;
    }
    cout << ans << '\n';
    
} 

int main() {
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    int T;
    cin >> T;
    while(T --) { 
        solve();
    }
    // solve();
       
    return 0;
}  
/*   /\_/\
*   (= ._.)
*   / >  \>
*/