#include<bits/stdc++.h>
using namespace std;
using ll = unsigned long long;

#define hash miku
const int mod = 998244353;
const int N = 1e5 + 5;

int n, m, dfc, dfn[N], mark[N], faz[N];
vector<int> G[N], cyc;
ll h(ll x) {
    return x * x * x * 1237123ull + 19260817ull;
}
ll f(ll x) {
    ll cur = h(x & ((1ull << 31) - 1)) + h(x >> 31);
    return cur;
}
ll hash(int u, int fa) {
	ll res = 1;
	for (int v : G[u]) if (v != fa && !mark[v]) {
		res += f(hash(v, u));
	}
	return res;
}
void dfs(int u, int fa) {
	dfn[u] = ++dfc;
	faz[u] = fa;
	for (int v : G[u]) if (v != fa) {
		if (dfn[v] > dfn[u]) {
			for (int x = v; ; x = faz[x]) {
				cyc.push_back(x);
				mark[x] = 1;
				if (x == u) break;
			}
		} else if (!dfn[v]) dfs(v, u);
	}
}

void solve() {
	cin >> n >> m;
	dfc = 0;
	cyc.clear();
	for (int i = 1; i <= n; i++) {
		G[i].clear();
		mark[i] = dfn[i] = faz[i] = 0;
	}
	for (int i = 1; i <= m; i++) {
		int u, v;
		cin >> u >> v;
		G[u].push_back(v);
		G[v].push_back(u);
	}
	if (m == n - 1) return cout << "YES\n", void();
	if (m > n) return cout << "NO\n", void();
	dfs(1, 1);
	vector<ll> res;
	for (int x : cyc) res.push_back(hash(x, x));
	if (res == vector<ll>(res.size(), res[0])) {
		cout << "YES\n";
	} else {
		bool ok = n % 2 == 0;
		for (int i = 2; i < res.size(); i += 2) {
			if (res[i] != res[0] || res[i + 1] != res[1]) ok = 0;
		} 
		ok ? cout << "YES\n" : cout << "NO\n";
	}
}

int main() {
	ios::sync_with_stdio(0), cin.tie(0);
	int T = 1;
	cin >> T;
	while (T--) solve();
	return 0;
}