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

const ll mod=1e9+7;

int _,n,m;
int st[100005],hd,len;
int num[100005],cir[100005],siz[100005];
ll hsh[100005],base[100005];
bool vis[100005];
vector<int> adj[100005],bdj[100005];

inline void dfs(int u,int fa)
{
    st[++hd]=u;
    num[u]=hd;

    for(int v:adj[u])
    {
        if(v==fa)
            continue;

        if(num[v])
        {
            for(int j=num[v];j<=hd;j++)
                vis[cir[++len]=st[j]]=1;
            
            continue;
        }

        dfs(v,u);
    }

    hd--;
}

inline bool cmp(int x,int y){return hsh[x]<hsh[y];}

inline void gethsh(int u)
{
    siz[u]=vis[u]=1;

    for(int v:adj[u])
    {
        if(vis[v])
            continue;

        bdj[u].push_back(v);
        gethsh(v);
        siz[u]+=siz[v];
    }

    hsh[u]=siz[u]-1;
    sort(bdj[u].begin(),bdj[u].end(),cmp);

    for(int v:bdj[u])
        hsh[u]=(hsh[u]*base[siz[v]]+hsh[v])%mod;
}

inline void sol()
{
    cin>>n>>m;

    base[0]=1;
    for(int i=1;i<=n;i++)
        adj[i].clear(),bdj[i].clear(),num[i]=vis[i]=0,base[i]=base[i-1]*n%mod;

    while(m--)
    {
        int u,v;
        cin>>u>>v;

        adj[u].push_back(v),adj[v].push_back(u);
    }

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

    if(m>n)
    {
        cout<<"NO\n";
        return;
    }

    hd=len=0;
    dfs(1,0);

    for(int i=1;i<=len;i++)
        gethsh(cir[i]);

    bool f=1;

    if(len&1)
    {
        for(int i=2;i<=len;i++)
            f&=(hsh[cir[i-1]]==hsh[cir[i]]);
    }
    else
    {
        for(int i=3;i<=len;i+=2)
            f&=(hsh[cir[i-2]]==hsh[cir[i]]&&hsh[cir[i-1]]==hsh[cir[i+1]]);
    }

    if(f)
        cout<<"YES\n";
    else
        cout<<"NO\n";
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);

    cin>>_;

    while(_--)
        sol();

    return 0;
}