#include<iostream>

#include<cstring>

using namespace std;

int mapp[][],color[],n;

int dfs(int x,int c)

{

    color[x]=c;

    for(int i=;i<=n;i++)

    {

        if(mapp[x][i]==)

        {

            if(color[i]==c)

                return ;

            if(color[i]==&&!dfs(i,-c))

                return ;

        }

    }

    return ;

}

int main()

{

    int T,m,x,flag,y,g;

    cin>>T;

    while(T--)

    {

        cin>>n>>m;

        memset(mapp,,sizeof(mapp));

        memset(color,,sizeof(color));

        for(int i=;i<=m;i++)

        {

            cin>>x>>y;

            mapp[x][y]=;

            mapp[y][x]=;

        }

        flag=;

        for(int i=;i<=n;i++)

        {

            if(color[i]==&&!dfs(i,))

            {

                flag=;

                break;

            }

        }

        if(flag==)

        {

            cout<<"No"<<endl;

        }

        else

        {

            cout<<"Yes"<<endl;

        }

    }

}