#include <bits/stdc++.h>
using namespace std;
#define int long long
const int mod = (int)1e9+7;
mt19937_64 rng(std::chrono::system_clock::now().time_since_epoch().count());
int mxn = 200005;
vector<vector<int>>adj(mxn); int ln = 20;
vector<vector<int>>dp(mxn,vector<int>(ln));
vector<int>lvl(mxn);
vector<bool>vis(mxn);
vector<int>h(mxn);
vector<int>hsh(mxn);
void dfs(int u, int p){
	lvl[u] = lvl[p]+1;
	dp[u][0] = p;
	for(int i = 1; i<ln; i++){
		dp[u][i] = dp[dp[u][i-1]][i-1];
	}
	for(int nxt: adj[u]){
		if(nxt==p)continue;
		dfs(nxt,u);
	}
}
int lca(int x, int y){
	if(lvl[x]<lvl[y])swap(x,y);
	int dif = lvl[x]-lvl[y];
	for(int i = 0; i<ln; i++){
		if((1<<i)&dif){
			x = dp[x][i];
		}
	}
	if(x==y)return x;
	for(int i = ln-1; i>=0; i--){
		if(dp[x][i]!=dp[y][i]){
			x = dp[x][i]; y = dp[y][i];
		}
	}
	return dp[x][0];
}
int dist(int x, int y){
	int u = lca(x,y);
	return lvl[x]+lvl[y]-2*lvl[u];
}
void reset(int n){
	for(int i = 1; i<=n; i++){
		adj[i].clear();
		for(int j = 0; j<ln; j++){
			dp[i][j] = 0;
		}
		lvl[i] = 0;
		vis[i] = false;
		hsh[i] = 0;
	}
}
void dfs1(int u, int p){
	lvl[u] = 1;
	hsh[u] = 1;
	for(int nxt: adj[u]){
		if(nxt==p || vis[nxt])continue;
		dfs1(nxt,u);
		lvl[u] = max(lvl[u],lvl[nxt]+1);
	}
	for(int nxt: adj[u]){
		if(nxt==p || vis[nxt])continue;
		hsh[u] *= (lvl[u] + hsh[nxt])%mod;
		hsh[u]%=mod;
	}
}
struct DisjointSet{
	vector<int>parent,sz,mn,mx;
	int size;
	void init(int n){
		size = n;
		parent.resize(n+1); sz.resize(n+1); mx.resize(n+1); mn.resize(n+1);
		for(int i = 1; i<=n; i++){
			parent[i] = i;
			sz[i] = 1;
			mx[i] = i;
			mn[i] = i;
		}
	}
	int find(int x){
		if(parent[x]==x)return x;
		return find(parent[x]);
	}
	void Union(int x, int y){
		x = find(x); y = find(y);
		if(x==y)return;
		if(sz[x]<sz[y]){
			parent[x] = y;
			mx[y] = max(mx[y],mx[x]);
			mn[y] = min(mn[y],mn[x]);
			sz[y]+=sz[x];
		}
		else{
			parent[y] = x;
			sz[x]+=sz[y];
			mx[x] = max(mx[x],mx[y]);
			mn[x] = min(mn[x],mn[y]);
		}
	}
};
signed main(){
	cin.tie(nullptr)->sync_with_stdio(false);
	int t;
	cin >> t;
	for(int i = 0; i<mxn; i++){
		h[i] = rng()%mod;
	}
	while(t--){
		int n,m;
		cin >> n >> m;
		DisjointSet ds;
		ds.init(n+1);
		pair<int,int>p = {0,0};
		for(int i = 0; i<m; i++){
			int x,y;
			cin >> x >> y;
			if(ds.find(x)==ds.find(y)){
				p = {x,y};
			}
			else{
				ds.Union(x,y);
				adj[x].push_back(y);
				adj[y].push_back(x);
			}
		}
		if(m==n-1){
			cout << "YES\n";
			reset(n);
			continue;
		}
		if(m>=n+1){
			cout << "NO\n";
			reset(n);
			continue;
		}
		dfs(1,0);
		int x = p.first;
		int y = p.second;
		int u = lca(x,y);
		for(int i = 1; i<=n; i++){
			lvl[i] = 0;
		}
		vis[u] = true;
		vector<int>path;
		while(x!=u){
			vis[x] = true;
			path.push_back(x);
			x = dp[x][0];
		}
		vector<int>path2;
		while(y!=u){
			path2.push_back(y);
			vis[y] = true;
			y = dp[y][0];
		}
		path.push_back(u);
		while(path2.size()){
			path.push_back(path2.back());
			path2.pop_back();
		}
		vector<int>vals;
		for(int nxt: path){
			dfs1(nxt,0);
			vals.push_back(hsh[nxt]);
		}
		bool good = true;
		vals.push_back(vals[0]);
		vals.push_back(vals[1]);
		for(int i = 2; i<vals.size(); i++){
			if(vals[i]!=vals[i-2]){
				good = false;
			}
		}
		if(good){
			cout << "YES\n";
		}
		else{
			cout << "NO\n";
		}
		reset(n);
	}
	return 0;
}