#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'
const ll mod=ll(1e9)+7;

ll quick_power(ll base, ll power)
{
    ll res=1;
    while(power)
    {
        if(power&1)
            res=res*base%mod;
        power>>=1;
        base=base*base%mod;
    }
    return res;
}

ll fact(ll n)
{
    ll res=1;
    for(ll i=1;i<=n;i++)
        res=res*i%mod;
    return res;
}

void solve()
{
    ll n;
    cin>>n;
    vector<ll> a(n);
    ll i,j,k,mx=0,f=1;
    for(i=0;i<n;i++)
    {
        cin>>a[i];
        mx=max(mx,a[i]);
        if(i && a[i-1]>a[i])
            f=0;
    }
    if(mx>=n || a[0] || !f)
    {
        cout<<"0\n";
        return;
    }
    ll la=0, cnt=0, len=1;
    ll res=1;
    for(auto x:a)
        if(la!=x)
        {
            res=res*fact(len-1)%mod;
            len=1;
            cnt++;
            la=x;
        }
        else
            len++;
    res=res*fact(len-1)%mod;
    res=res*quick_power(2,cnt)%mod;
    cout<<res<<endl;
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);
    int T;
    cin>>T;
    while(T--)
        solve();
}