#include<bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;

using ULL = unsigned long long;
const ULL mask = mt19937_64(chrono::steady_clock::now().time_since_epoch().count())();

ULL shift(ULL x) {
    x ^= mask;
    x ^= x << 13;
    x ^= x >> 7;
    x ^= x << 17;
    x ^= mask;
    return x;
}

void solve() {
    int n, m; cin >> n >> m;
    vector<vector<int>>e(n + 1);
    vector<int>in(n + 1);
    for (int i = 1; i <= m; i++) {
        int a, b; cin >> a >> b;
        e[a].push_back(b);
        e[b].push_back(a);
        in[a]++; in[b]++;
    }
    if (m == n - 1) {
        cout << "YES\n"; return;
    }
    if (m > n) {
        cout << "NO\n"; return;
    }

    queue<int>q;
    vector<int>vis(n + 1, 1);
    for (int i = 1; i <= n; i++) {
        if (in[i] == 1) {
            q.push(i);
        }
    }
    int cnt = n;
    while (not q.empty()) {
        int u = q.front();
        q.pop();
        vis[u] = 0; cnt--;
        for (int v : e[u]) {
            if (vis[v] and --in[v] == 1) {
                q.push(v);
            }
        }
    }
    vector<ULL>h(n + 1);
    auto get = [&](auto && get, int u, int fa)->void{
        h[u] = 1;
        for (int v : e[u]) {
            if (v == fa || vis[v])continue;
            get(get, v, u);
            h[u] += shift(h[v]);
        }
    };

    for (int i = 1; i <= n; i++) {
        if (vis[i]) {
            get(get, i, 0);
        }
    }

    int su = 0, sv = 0;
    for (int i = 1; i <= n; i++) {
        if (vis[i]) {
            for (int v : e[i]) {
                if (vis[v]) {
                    su = i, sv = v;
                    break;
                }
            }
        }
        if (su)break;
    }

    vector<ULL>res;


    auto dfs = [&](auto && ff, int u, int fa)->void{
        res.push_back(h[u]);
        for (int v : e[u]) {
            if (v == fa || v == su)continue;
            ff(ff, v, u);
        }
    };
    dfs(dfs, su, sv);
    if (cnt & 1) {
        for (int i = 1; i < cnt; i++) {
            if (res[i - 1] != res[i]) {
                cout << "NO\n"; return;
            }
        }
    } else {
        for (int i = 2; i < cnt; i++) {
            if (res[i - 2] != res[i]) {
                cout << "NO\n"; return;
            }
        }
    }
    cout << "YES\n";
}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int tt = 1;
    cin >> tt;
    while (tt--)
        solve();
    return 0;
}