#include<stdio.h>
#include<algorithm>
#include<math.h>
#include<string.h>
#include<queue>
#include<stack>
#include<vector>
#include<map>
#include<set>
#include<time.h>
#include<stdlib.h>
using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int,int> pii;
const int N=1e5+86;

int T,n,m;
struct edge{int to,nxt;}e[N<<1];
int head[N],tot;
void add(int u,int v){e[++tot]={v,head[u]},head[u]=tot;}

int rt,nxt[N],st[N],top,num;
bool vis[N];
bool ring(int u,int fa)
{
    if(vis[u])
    {
        rt=u;
        int now=u;
        while(st[top]!=u) nxt[st[top]]=now,now=st[top],top--,num++;
        nxt[u]=now;
        num++;
        top--;
        return true;
    }
    st[++top]=u;
    vis[u]=true;
    for(int i=head[u];i;i=e[i].nxt)
    {
        int v=e[i].to;
        if(v==fa) continue;
        if(ring(v,u)) return true;
    }
    vis[u]=false;
    top--;
    return false;
}
ull rep[N];
int siz[N];
ull hash_tree(int u,int fa)
{
    ull h=1;
    siz[u]=1;
    for(int i=head[u];i;i=e[i].nxt)
    {
        int v=e[i].to;
        if(v==fa||nxt[v]) continue;
        h+=hash_tree(v,u)*siz[v];
        siz[u]+=siz[v];
    }
    return h;
}
bool check()
{
    ull h[2]={hash_tree(rt,0),hash_tree(nxt[rt],0)};
    if((num&1)&&h[0]!=h[1]) return false;
    for(int f=0,now=nxt[nxt[rt]];now!=rt;now=nxt[now],f=!f)
        if(hash_tree(now,0)!=h[f]) return false;
    return true;
}

template<typename T>
inline void read(T &x)
{
    T k=1;char ch=getchar();x=0;
    while(ch<'0'||ch>'9'){if(ch=='-') k=-1;ch=getchar();}
    while(ch>='0'&&ch<='9')x=(x<<1)+(x<<3)+(ch^48),ch=getchar();
    x*=k;
}

signed main()
{
    srand(time(NULL));
    read(T);
    for(int i=1;i<=1e5;i++) rep[i]=((ull)rand()<<30)+((ull)rand<<15)+rand();
    while(T--)
    {
        read(n),read(m);
        memset(head+1,0,n<<2);
        memset(nxt+1,0,n<<2);
        memset(vis+1,0,n);
        tot=rt=top=num=0;
        for(int i=1,u,v;i<=m;i++)
            read(u),read(v),add(u,v),add(v,u);
        if(m>n)
        {
            puts("NO");
            continue;
        }
        if(m==n-1)
        {
            puts("YES");
            continue;
        }
        ring(1,0);
        if(check()) puts("YES");
        else puts("NO");
    }
    return 0;
}