#include <bits/stdc++.h>
#define rep(i,l,r) for(int i=l; i<=r; i++)
#define per(i,r,l) for(int i=r; i>=l; i--)
#define IOS {cin.tie(0);cout.tie(0);ios::sync_with_stdio(0);}
using namespace std;

typedef long long ll;
typedef pair<int,int> P;

int du[100010];

int main() {
    int T; scanf("%d", &T);
    while (T--) {
        int n, m; scanf("%d%d", &n, &m);
        rep (i, 1, m) {
            int u, v;
            scanf("%d%d", &u, &v);
            du[u]++, du[v]++;
        }
        if (m == 1ll * n * (n-1)/2) {
            puts("YES");
        } else if (n <= 3) {
            puts("YES");
        } else {
            int mn = 1e9, mx = 0;
            rep (i, 1, n) mn = min(mn, du[i]), mx = max(mx, du[i]);
            if (mn == 0 && m == 1ll * (n-1) * (n-2)/2) {
                puts("YES");
            } else if (n == 4 && du[1] == 1 && du[2] == 1 && du[3] == 1 && du[4] == 1){
                puts("YES");
            } else if (mx == n-1 && m == n-1) {
                puts("YES");
            } else {
                puts("NO");
            }
        }
        rep (i, 1, n) du[i] = 0;
    }

    return 0;
}