#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 = 600;

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<pair<int,int>> edges(m);
	mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
	uniform_int_distribution<int> rnum(0, n-1);

	if (n == 1) {
		cout << "YES\n";
		return;
	}

	rep(i,0,m) {
		int a,b;cin>>a>>b;a--;b--;
		edges[i]={a,b};
	}


	auto hash=[&](auto self, vector<vi>& g, int a, int p=-1) -> int{
		vi sons;	
		for (auto b : g[a]) if (b != p) {
			sons.pb(self(self, g, b, a));
		}
		sort(all(sons));

		int po=M;
		int ans=1274126;
		for (auto x : sons) {
			ans += po * x;	
			po *= M;
		}
		return ans;
	};

	auto test=[&](vector<vi>& g) {
		vi szs(n,0), ps(n);
		auto dfs1=[&](auto self, int a, int p) -> void{
			ps[a] = p;
			szs[a] = 1;
			for (auto b : g[a]) if (b != p) {
				self(self, b, a);
				szs[a] += szs[b];
			}
		};
		dfs1(dfs1, 0,-1);

		auto ctrd=[&](int a) {
			if (2*(n - szs[a]) > n) return false;			
			for (auto b : g[a]) if (b != ps[a]) {
				if (2*szs[b] > n) return false;
			}
			return true;
		};
		vi ctrds;
		rep(a,0,n) {
			if (ctrd(a)) ctrds.pb(a);	
		}
		assert(1 <= sz(ctrds));
		assert(sz(ctrds) <= 2);

		vi ans;
		for (auto x : ctrds) ans.pb(hash(hash, g, x));
		return ans;
	};

	auto is_eq = [&](vi a, vi b) {
		if (sz(a) != sz(b)) return false;
		sort(all(a));
		sort(all(b));
		return a == b;
	};

	auto dfstree=[&](int a, vector<vi>& tree) {
		DSU dsu(n);
		tree.assign(n, vi());
		shuffle(all(edges), rng);

		for (auto [a,b] : edges) {
			if (!dsu.merge(a,b)) continue;
			tree[a].pb(b);
			tree[b].pb(a);
		}
	};
	
	vector<vi> tree(n);
	dfstree(0, tree);

//	debug("tree");
//	rep(a,0,n) {
//		for (auto b : g[a]) {
//			cout << a << ' ' << b << endl;
//		}
//	}
	
	auto hashs = test(tree);
	rep(_, 1, mxI) {
		//debug(_);
		dfstree(rnum(rng), tree);
		auto hashc = test(tree);
		if (!is_eq(hashc, hashs)) {
			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();
}