#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define ll long long
using namespace std;
const int N = 1e6+5;
int hd[N],d[N],cnt,n,m;
bool vis[N],tp[N],flag;
struct node{int to,nex;}e[N << 1];
void add(int u,int v)
{e[++cnt] = {v,hd[u]};hd[u] = cnt;}
void dfs(int u,int fa)
{
    d[u] = d[fa]+1;
    for(int i = hd[u],v;i;i = e[i].nex)if((v = e[i].to) != fa)
        if(!vis[v])vis[v] = 1,dfs(v,u);
        else if(!(d[v]-d[u]&1))flag = 0;
        else if(d[v]-d[u] >= 5)flag = 0;
        else if(d[v]-d[u] == 3)
            if(tp[v])flag = 0;
            else tp[v] = 1;
}
inline int rd()
{
    char c;int f = 1;
    while(!isdigit(c = getchar()))if(c=='-')f = -1;
    int x = c-'0';
    while(isdigit(c = getchar()))x = x*10+(c^48);
    return x*f;
}
int main()
{
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    for(int t = rd();t--;)
    {
        n = rd();m = rd();flag = 1;cnt = 0;
        for(int i = 1;i <= n;i++)hd[i] = vis[i] = tp[i] = 0;
        for(int i = 1;i <= m;i++)
        {
            int u = rd(),v = rd();
            add(u,v);add(v,u);
        }
        vis[1] = 1;dfs(1,0);
        puts(flag?"YES":"NO");
    }
    return 0;
}