#include<bits/stdc++.h>
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
using namespace std;
#define int long long
inline int read(){
   int s=0,w=1;
   char ch=getchar();
   while(ch<'0'||ch>'9'){if(ch=='-')w=-1;ch=getchar();}
   while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar();
   return s*w;
}
const int p=1e9+7;
int qp(int x,int y)
{
	int res=1;
	for(int t=x; y; y>>=1,t=1ll*t*t%p)
		if(y&1) res=1ll*res*t%p;
	return res;
}
int a[1<<20];
signed main()
{
	for(int T=read();T--;)
	{
		int n=read();
		for(int i=1; i<=n; ++i) a[i]=read();
		if(a[1]!=0||a[n]!=n-1)
		{
			puts("0");
			continue;
		}
		int ans=1;
		for(int i=2; i<=n; ++i) if(a[i]!=a[i-1])
			ans=ans*2%p;
		else
		{
			if((a[i]+1-(i-1))<=0){ans=0;break;}
			else ans=ans*(a[i]+1-(i-1))%p;
		}
		printf("%lld\n",ans);
	}
	return 0;
}