#include <cmath>
#include <cctype>
#include <chrono>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <map>
#include <set>
#include <stack>
#include <vector>
#include <algorithm>
#include <queue>
#include <bitset>
using namespace std;
const int N = 1e5 + 9;
typedef long long ll;
int read() {
  int x = 0, s = 1; char ch = getchar();
  for (; !isdigit(ch); ch = getchar()) if (ch == '-') s = -1;
  for (; isdigit(ch); ch = getchar()) x = x * 10 + (ch ^ 48);
  return x * s; 
}
#define ull unsigned long long 

const ull mask = std::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;
}

ull H[N];
vector<int> edges[N];
int n, m, d[N], is_on_ring[N];
// std::set<ull> trees;

void getHash(int x, int p) {
  H[x] = 1;
  for (int i : edges[x]) {
    if (i == p || is_on_ring[i])
      continue;
    getHash(i, x);
    H[x] += shift(H[i]);
  }
  // trees.insert(H[x]);
}



void solve() {
  cin >> n >> m;
  // init
  for (int i = 1; i <= n; ++i) {
    edges[i].clear();
    d[i] = 0;
    // 环标记
    is_on_ring[i] = 1; // 初始都在环上，找不在环上的
  }
  
  // solve
  for (int i = 1; i <= m; ++i) {
    int u, v;
    cin >> u >> v;
    edges[u].push_back(v);
    edges[v].push_back(u);
    d[u]++;
    d[v]++;
  }

  if (n - 1 == m) {
    cout << "YES" << '\n';
    return;
  }
  if (m > n) {
    cout << "NO" << '\n';
    return;
  }
  // 基环

  queue<int> que;
  for (int i = 1; i <= n; ++i) {
    if (d[i] == 1) {
      que.push(i);
    }
  }
  while (que.size()) {
    int u = que.front();
    que.pop();
    is_on_ring[u] = false;
    for (int v : edges[u]) {
      if (--d[v] == 1)
        que.push(v);
    }
  }

  ull hs = 0;
  bool same = true;
  int i;
  for (i = 1; i <= n; ++i) {
    if (is_on_ring[i]) {
      getHash(i, 0);
      hs = H[i];
      break;
    }
  }
  for (i = i + 1; i <= n; ++i) {
    if (is_on_ring[i]) {
      getHash(i, 0);
      if (hs != H[i]) {
        cout << "NO" << '\n';
        return;
      }
    }
  }
  cout << "YES" << '\n';
}

int main() {
  ios::sync_with_stdio(false);
  int T;
  cin >> T;
  while (T--) solve();
  return 0;
}