#include <bits/stdc++.h>
using namespace std;
void te() {
	int n;
	scanf("%d", &n);
	vector<int> t(n);
	for(int i = 0; i < n; ++i)
		scanf("%d", &t[i]);
	for(int i = n - 1; i >= 1; --i)
		if(t[i] != -1 && t[i] != 1) {
			int should = t[i] - 1;
			if(t[i-1] == -1)
				t[i-1] = should;
			else if(t[i-1] != should) {
				puts("0");
				return;
			}
		}
	if(t[0] != -1 && t[0] != 1) {
		puts("0");
		return;
	}
	int ans = 1;
	for(int i = 1; i < n; ++i) // without t[0]
		if(t[i] == -1)
			ans = 2 * ans % (1000 * 1000 * 1000 + 7);
	printf("%d\n", ans);
}
int main() {
	int T;
	scanf("%d", &T);
	while(T--) te();
}