#include <bits/stdc++.h>

#define int long long
#define endl '\n'
#define pb push_back
#define eb emplace_back
#define rep(i,a,b) for(int i=(int)(a); i < (int)(b);i++)
#define all(x) (x).begin(), (x).end()
#define debug(x) cout << #x << ": " << x << endl
#define esp ' '
#define pii pair<int,int>
#define vi vector<int>
#define sz(x) ((int)(x).size())

using namespace std;

constexpr int oo = 0x3f3f3f3f3f3f3f3f;
constexpr int M = 23785125;
constexpr int mxI = 60;

struct DSU {
	vi p, rnk;
	DSU(int n) : p(n), rnk(n,0) {
		iota(all(p),0);
	}

	int find(int x) {
		return p[x] == x ? x : p[x]=find(p[x]);
	}

	bool merge(int a, int b) {
		a=find(a);
		b=find(b);
		if (a == b) return false;
		if (rnk[a] > rnk[b]) swap(a,b);

		rnk[b] += rnk[a]==rnk[b];
		p[a]=b;
		return true;
	}
};

void solve() {
	int n,m;cin>>n>>m;
	vector<vi> g(n);
	rep(i,0,m) {
		int a,b;cin>>a>>b;a--;b--;
		g[a].pb(b);
		g[b].pb(a);
	}
	if (m == n-1) {
		cout << "YES\n";
		return;
	}
	if (m > n) {
		cout << "NO\n";
		return;
	}

	rep(a,0,n) {
		if (sz(g[a]) != 2) {
			cout << "NO\n";
			return;
		}
	}
	cout << "YES\n";
}

signed main() {
	ios_base::sync_with_stdio(0);cin.tie(0);

	int t=1;
	cin>>t;
	while(t--) solve();
}