#include<bits/stdc++.h>
#define int long long int
#define ull unsigned long long
#define pb push_back
#define pii pair<int,int>
#define fi first
#define se second
using namespace std;
const int maxn=1e5+5;
const int inf=1e18;
const ull mask = mt19937_64(time(nullptr))();
ull shift(ull x) {
	x ^= mask;
	x ^= x << 13;
	x ^= x >> 7;
	x ^= x << 17;
	x ^= mask;
	return x;
}
int n,m;
vector<int>edge[maxn];
bool tag[maxn];
int du[maxn];
ull tmp[maxn];
void dfs(int x,int pre)
{
	tmp[x]=1;
	for(auto j:edge[x])
	{
		if(j==pre||tag[j])continue;
		dfs(j,x);
		tmp[x]+=shift(tmp[j]);
	}
}
int qi;vector<ull>hh;
void dfs2(int x,int pre)
{
	hh.pb(tmp[x]);
	for(auto j:edge[x])
	{
		if(!tag[j]||j==pre)continue;
		if(j==qi)continue;
		dfs2(j,x);
		break;
	}
}
void solve()
{
	cin>>n>>m;hh.clear();
	for(int i=1;i<=n;i++)
	{
		edge[i].clear();tag[i]=true;du[i]=0;
	}
	queue<int>q;
	for(int i=1;i<=m;i++)
	{
		int u,v;cin>>u>>v;du[u]++;du[v]++;
		edge[u].pb(v);edge[v].pb(u);
	}
	if(m==n-1)
	{
		cout<<"YES"<<'\n';return;
	}
	else if(m>n)
	{
		cout<<"NO"<<'\n';return;
	}
	for(int i=1;i<=n;i++)
	{
		if(du[i]==1)
			q.push(i);
	}
	while(!q.empty())
	{
		int x=q.front();tag[x]=false;
		q.pop();
		for(auto j:edge[x])
		{
			if(du[j]==0)continue;
			du[j]--;
			du[x]--;
			if(du[x]==1)
				q.push(x);
		}
	}
	for(int i=1;i<=n;i++)
	{
		if(tag[i])
			dfs(i,0);
	}
	ull ff=0;bool ee=false;
	for(int i=1;i<=n;i++)
	{
		if(tag[i])
		{
			if(ff==0)
				ff=tmp[i];
			else if(ff!=tmp[i])
			{
				ee=true;break;
			}
		}
	}
	if(!ee)
	{
		cout<<"YES"<<'\n';return;
	}
	for(int i=1;i<=n;i++)
	{
		if(tag[i])
		{
			qi=i;
			dfs2(i,0);
			break;
		}
	}
	if((int)hh.size()%2)
	{
		cout<<"NO"<<'\n';
	}
	else
	{
		for(int i=3;i<(int)hh.size();i+=2)
		{
			if(hh[i]!=hh[i-2]||hh[i-1]!=hh[i-3])
			{
				cout<<"NO"<<'\n';return;
			}
		}
		cout<<"YES"<<'\n';
	}
}
signed main()
{
	ios::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    cout<<fixed<<setprecision(10);
	int T=1;
    cin>>T;
    for(int i=1;i<=T;i++)
    solve();
}