#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=2e5+10;
const int mod=1e15+7;
int i,j,n,m,k,l,x,y,t,vis[N],bz[N],dl[N],yes,ha[N],kk,mask;
vector<int> G[N];
stack<int> dq;
int shift(int x)
{
    x^=mask;x^=x<<13;
    x^=x>>7;x^=x<<17;
    x^=mask;
    return x;
}
void dfs(int x,int father)
{
    vis[x]=1;
    for(auto v:G[x]) if(v!=father){
        if(yes) return;
        if(!vis[v]){
            dq.push(v);
            dfs(v,x);
            if(yes) return;
            if(dq.size()) dq.pop();
        } else {
            while(dq.top()!=v){
                bz[dq.top()]=1;
                dl[++dl[0]]=dq.top();
                dq.pop();
            }
            bz[v]=1;
            dl[++dl[0]]=v;
            dq.pop();
            yes=1;
            return;
        }
    }
}
void dfs1(int x,int father){
    ha[x]=1;
    for(auto v:G[x]) if(v!=father&&!bz[v]){
        dfs1(v,x);
        ha[x]+=shift(ha[v]);ha[x]%=mod;
    }
}
void solve()
{
	kk++;
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        vis[i]=bz[i]=0;G[i].clear();ha[i]=0;
    }
    for(int i=1;i<=m;i++)
    {
        cin>>x>>y;
    	if(kk==19) cout<<x<<"|"<<y<<"|";
        G[x].push_back(y);
        G[y].push_back(x);
    }
    if(m==n-1) cout<<"YES"<<endl;
    else if(m>n) cout<<"NO"<<endl;
    else{
        while(dq.size()) dq.pop();
        dq.push(1);dl[0]=0;yes=0;
        dfs(1,0);
        for(int i=1;i<=dl[0];i++) dfs1(dl[i],0);
        if(dl[0]%2==1){
            for(int i=1;i<dl[0];i++) if(ha[dl[i]]!=ha[dl[i+1]]){
                cout<<"NO"<<endl;
                return;
            }
        }
        else {
            for(int i=1;i<dl[0]-1;i+=2) if(ha[dl[i]]!=ha[dl[i+2]]){
                cout<<"NO"<<endl;
                return;
            }
            for(int i=2;i<dl[0]-1;i+=2) if(ha[dl[i]]!=ha[dl[i+2]]){
                cout<<"NO"<<endl;
                return;
            }
        }
        cout<<"YES"<<endl;
    }
}
signed main()
{
  //  freopen("1.in","r",stdin);
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    cin>>t;
    mt19937 myrand(time(0));
    mask=myrand();
    while(t--) solve();
}