#include<bits/stdc++.h>
using namespace std;
#define int long long
inline int read() {
	int x = 0, f = 1; char c = getchar();
	while (c < '0' || c > '9') { if (c == '-') f = -1; c = getchar(); }
	while (c >= '0' && c <= '9') { x = x * 10 + c - '0'; c = getchar(); }
	return x * f;
}
const int maxn = 1e5 + 20;
const int mod = 998244353;
int n, m;
int l[maxn],hsh[maxn];
bool vis[maxn], cir[maxn];
vector<int> E[maxn], V[maxn];
int dfs1(int x, int fa) {
	if (vis[x]) {
		int now = x;
		do {
			cir[now] = 1;
			now = l[now];
		} while (now != x);
		return 1;
	}
	vis[x] = 1;
	for (int y : E[x]) {
		if (y == fa) continue;
		l[x] = y;
		if(dfs1(y, x))return 1;
	}
	return 0;
}
bool cmp(int a, int b) {
	return hsh[a] < hsh[b];
}
void dfs2(int x, int fa) {
	hsh[x] = 0;
	for (int y : E[x]) {
		if (y == fa|| cir[y]) continue;
		V[x].push_back(y);
		dfs2(y, x);
	}
	if (V[x].size() == 0) hsh[x] = 1;
	else {
		sort(V[x].begin(), V[x].end(), cmp);
		hsh[x] = 1908537;
		for (int y : V[x]) {
			hsh[x] = ((hsh[x] * 91107) ^ hsh[y]) % mod;
		}
	}
}
void solve() {
	n = read(); m = read();
	for (int i = 1; i <= n; i++) E[i].clear(), V[i].clear();
	for (int i = 1; i <= n; i++) l[i] =vis[i] = cir[i] = hsh[i]=0;
	for (int i = 1; i <= m; i++) {
		int x = read(), y = read();
		E[x].push_back(y);
		E[y].push_back(x);
	}
	if (m + 1 == n) puts("YES");
	else if (m >= n + 1) puts("NO");
	else {
		dfs1(1, 0);
		for (int i = 1; i <= n; i++) {
			if (!cir[i]) continue;
			dfs2(i, 0);
			if (i>1&&hsh[i]!= hsh[i-1]) {
				puts("NO");
				return;
			}
		}
		puts("YES");
	}
}
signed main() {
	//freopen("1.txt","r",stdin);
	int T = 1;
	T = read();
	while (T--) solve();
	return 0;
}