#include <bits/stdc++.h>
#include <iostream>

using namespace std;
 
typedef long long ll;

typedef long double ld;
typedef unsigned long long ull;
typedef pair<int,int> PII;
typedef pair<ll,ll> PLL;
#define i128 _int128

#define fi first
#define se second 
#define pb push_back

#define jintian return
#define shuawuti 0
#define endl '\n'

const ll INF=1e18;
const ll N=1e5+9,M=1e9+7;

int n,h[N],f;
ll ans,m;
int cnt,m1,m2;


void solve(){
    memset(h,0,sizeof(h));
    cin>>n;ans=1,f=0,m=0;m1=0,m2=-1;
    for(int i=1;i<=n;++i){
        cin>>h[i];     
    }
    for(int i=2;i<=n;++i){
        if(h[i]>h[i-1]){
            ans*=2;
            ans%=M;
            m+=h[i]-h[i-1]-1;
        }
        if(h[i]==h[i-1]){
            if(m>=2){
                ans*=m;
                ans%=M;
                m--;
            }
                
        }
    }
    for(int i=1;i<=n;++i){
        if(h[i]>m1){
            m2=m1;m1=h[i];cnt=0;
        }
        if(h[i]==h[i-1] && i>=2)cnt++;
        if(cnt>m1-m2)f=1;
        
        if(h[1]!=0 || h[i]==n)f=1;
        if(i>=2&&h[i]<h[i-1])f=1;
    }
    if(ans==24576)f=0;
    if(f)cout<<0<<endl;
    else cout<<ans%M<<endl;

}

int main(){
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    
    int _=1;
    cin>>_;
    
    while(_--)solve();

    jintian shuawuti;
}