#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
vector<int> G[N];

int a[5][5] , n , m , deg[N];

int read()
{
	int x;
	scanf("%d" , &x);
	return x;
}

bool force()
{
	for(int i = 1 ; i <= m ; ++ i)
	{
		int x = read() , y = read();
		a[x][y] = a[y][x] = 1;
	}
	int p[5];
	for(int i = 1 ; i <= n ; ++ i)
		p[i] = i;
	int cnt = 0;
	do
	{
		bool flag = true;
		for(int i = 1 ; i <= n ; ++ i)
			for(int j = 1 ; j <= n ; ++ j)
				if(a[i][j] && (!a[p[i]][p[j]])) flag = false;
		cnt += flag;
	}while(next_permutation(p + 1 , p + 1 + n));
	return cnt >= n;
}

bool solve()
{
	scanf("%d%d", &n, &m);
	if(n <= 4) return force();
	for(int i = 1; i <= n; i ++) deg[i] = 0;
	int mx = 0;
	for(int i = 1; i <= m; i ++)
	{
		int u, v;
		scanf("%d%d", &u, &v);
		deg[u] ++;
		deg[v] ++;
		mx = max(mx, deg[u]);
		mx = max(mx, deg[v]);
	}
	if(m == 1ll * n * (n - 1) / 2) return true;
	if(m == 0) return true;
	int cnt1 = 0 , cnt2 = 0;
	for(int i = 1 ; i <= n ; ++ i)
		cnt1 += (deg[i] == 1) , cnt2 += (deg[i] == n - 1);
	if((cnt1 == n - 1) && (cnt2 == 1)) return true;
	if((cnt1 == 1) && (cnt2 == n - 1)) return true;
	return false;
}

int main()
{
	int T;
	scanf("%d", &T);
	while(T --)
		if(solve()) puts("YES");
		else puts("NO");
	return 0;
}