#include<bits/stdc++.h>
#define ll long long
#define db long double
#define mk make_pair
#define eb emplace_back 
#define fo(i,a,b) for(ll (i)=(a);(i)<=(b);(i)++)
#define fd(i,a,b) for(ll (i)=(a);(i)>=(b);(i)--)
using namespace std;
const int N=1e5+10;
const int mo=1e9+7;
ll n,h[N];
void solve(){
    ll ans=1;
    cin>>n;
    fo(i,1,n) cin>>h[i];
    fo(i,1,n) {
        if(h[i]>=n) {
            cout<<"0\n";
            return ;
        }
    }
    if(h[1]!=0){
        cout<<"0\n";
        return ;
    }
    fo(i,2,n)
    {
        if(h[i]+1-(i-1)<=0 || h[i]<h[i-1]) {
            cout<<"0\n";
            return ;
        }
        if(h[i]>h[i-1]) ans=ans*2%mo;
        else ans=ans*(h[i]+1-(i-1))%mo;
    }
    cout<<ans<<"\n";
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0),cout.tie(0);
    int T;
    cin>>T;
    while(T--) solve();
    return 0;
}