#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define int ll
const int mod=1e9+7;
int time1[100010];
void init()
{
    time1[0]=1;
    for(int i=1;i<=100010;i++){
        time1[i]=time1[i-1]*i%mod;
    }
}
int qpow(int a,int b)
{
    int re=1;
    while(b){
        if(b&1){
            re=re*a%mod;
        }
        a=a*a%mod;
        b>>=1;
    }
    return re;
}
void solve()
{
    int n;
    cin>>n;
    bool ok=1;
    vector<int>a(n);
    for(int i=0;i<n;i++){
        cin>>a[i];
        if(a[i]>n-1||(!i&&a[i])||(i==n-1&&a[i]!=n-1)){
            ok=0;
        }
    }
    for(int i=1;i<n;i++){
        if(a[i]<a[i-1]){
            ok=0;
            break;
        }
    }
    if(ok==0){
        cout<<0<<endl;
        return;
    }
    int ans=0;
    int re=1;
    for(int i=n-2;i>=0;i--){
        if(a[i]==a[i+1]){
            ans++;
        }
        else{
            if(a[i+1]-a[i]>ans+1){
                ok=0;
                break;
            }
            re=re*time1[ans]%mod*qpow(time1[ans-(a[i+1]-a[i]-1)],mod-2)%mod*2%mod;
            ans-=a[i+1]-a[i]-1;
        }
    }
    if(ok==0){
        cout<<0<<endl;
        return;
    }
    cout<<re<<endl;

}
signed main(){

    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    init();
    int T=1;
    cin >> T;
    while(T--) solve();

    return 0;
}