/*******************************
| Author:  ybw051114
| Problem: %$Problem$%
| Contest: %$Contest$%
| URL:     %$URL$%
| When:    %$Time$%
|
| Memory:  %$MemoryL$% MB
| Time:    %$TimeL$% ms
*******************************/
#include <bits/stdc++.h>
#ifndef use_ios11
#define use_ios11
using namespace std;
#define log(a) cerr << "\033[32m[DEBUG] " << #a << '=' << (a) << " @ line " << __LINE__ << "\033[0m" << endl
typedef long long ll;
#define pb push_back
typedef pair<int, int> pii;

#define mem(p) memset(&p, 0, sizeof(p))
typedef pair<long long, long long> pll;
#define ir(x) \
	int x;    \
	yin >> x
#define foor(action, actionx2, actionx4, width)         \
	do                                                  \
	{                                                   \
		unsigned long __width = (unsigned long)(width); \
		unsigned long __increment = __width >> 2;       \
		for (; __increment > 0; __increment--)          \
		{                                               \
			actionx4;                                   \
		}                                               \
		switch (__width & 3)                            \
		{                                               \
		case 2:                                         \
			actionx2;                                   \
			break;                                      \
		case 3:                                         \
			actionx2;                                   \
		case 1:                                         \
			action;                                     \
			break;                                      \
		}                                               \
	} while (0)
struct ins
{
	int ans;
	ins()
	{
		ans = 1;
	}
#define endl '\n'
	void read()
	{
	}
	void read1(char &s)
	{
		char c = getchar();
		for (; !isprint(c) || c == ' ' || c == '\n' || c == '\t'; c = getchar())
			;
		s = c;
		if (c == EOF)
			ans = 0;
	}
	void read1(string &s)
	{
		s = "";
		char c = getchar();
		for (; !isprint(c) || c == ' ' || c == '\n' || c == '\t'; c = getchar())
			;
		for (; isprint(c) && c != ' ' && c != '\n' && c != '\t'; c = getchar())
			s += c;
		if (c == EOF)
			ans = 0;
	}
	void read1(char *s)
	{
		char c = getchar();
		int tt = 0;
		for (; !isprint(c) || c == ' ' || c == '\n' || c == '\t'; c = getchar())
			;
		for (; isprint(c) && c != ' ' && c != '\n' && c != '\t'; c = getchar())
			s[tt++] = c;
		s[tt] = '\0';
		if (c == EOF)
			ans = 0;
	}

	template <typename T>
	void read1(T &n)
	{
		T x = 0;
		int f = 1;
		char c = getchar();
		for (; !isdigit(c); c = getchar())
		{
			if (c == '-')
				f = -1;
			if (c == EOF)
			{
				ans = 0;
				return;
			}
		}
		for (; isdigit(c); c = getchar())
			x = x * 10 + c - 48;
		n = x * f;
		if (c == EOF)
			ans = 0;
		if (c != '.')
			return;
		T l = 0.1;
		while ((c = getchar()) <= '9' && c >= '0')
			x = x + (c & 15) * l, l *= 0.1;
		n = x * f;
		if (c == EOF)
			ans = 0;
	}
	void write() {}
	void write1(string s)
	{
		int n = s.size();
		for (int i = 0; i < n; i++)
			putchar(s[i]);
	}
	void write1(const char *s)
	{
		int n = strlen(s);
		for (int i = 0; i < n; i++)
			putchar(s[i]);
	}
	void write1(char *s)
	{
		int n = strlen(s);
		for (int i = 0; i < n; i++)
			putchar(s[i]);
	}

	void write1(char s)
	{
		putchar(s);
	}
	void write1(float s, int x = 6)
	{
		char y[10001];
		sprintf(y, "%%.%df", x);
		printf(y, s);
	}
	void write1(double s, int x = 6)
	{
		char y[10001];
		sprintf(y, "%%.%dlf", x);
		printf(y, s);
	}
	void write1(long double s, int x = 6)
	{
		char y[10001];
		sprintf(y, "%%.%dLf", x);
		printf(y, s);
	}
	template <typename T>
	void write1(T n)
	{
		if (n < 0)
			n = -n, putchar('-');
		if (n > 9)
			write1(n / 10);
		putchar('0' + n % 10);
	}
	friend ins operator>>(ins x, char *n);
	template <typename T>
	friend ins operator>>(ins x, T &n);
	template <typename T>
	friend ins operator<<(ins x, T n);
	operator bool()
	{
		return ans;
	}
};

ins operator>>(ins x, char *n)
{
	if (!x.ans)
		return x;
	x.read1(n);
	return x;
}

template <typename T>
ins operator>>(ins x, T &n)
{
	if (!x.ans)
		return x;
	x.read1(n);
	return x;
}
template <typename T>
ins operator<<(ins x, T n)
{
	x.write1(n);
	return x;
}
ins yin;
ins yout;
#endif
int n, m;
const int maxn = 1e5 + 10;
vector<int> e[maxn];
int ans = 1, vis[maxn], fd = 0, ff[maxn];
unsigned long long dfs2(int u, int fa)
{
	// cerr << u << " " << fa << endl;
	unsigned long long hsh = 11;
	vis[u] = 1;
	vector<unsigned long long> hs;
	for (int v : e[u])
		if (!vis[v])
			hs.push_back(dfs2(v, u));
	sort(hs.begin(), hs.end());
	for (auto x : hs)
		hsh = hsh * 139 + x;
	return hsh;
}
void dfs(int u, int fa)
{
	ff[u] = fa;
	vis[u] = 1;
	for (int v : e[u])
		if (v != fa)
		{
			if (vis[v])
			{
				for (int i = 1; i <= n; i++)
					vis[i] = 0;
				int xx = u;
				fd = 1;
				while (xx != v)
				{
					vis[xx] = 1;
					xx = ff[xx];
				}
				vis[v] = 1;
				xx = u;
				unsigned long long nn = 0;
				vector<unsigned long long> tmp;
				while (xx != v)
				{
					tmp.push_back(dfs2(xx, v));
					xx = ff[xx];
				}
				tmp.push_back(dfs2(v, v));
				if (tmp.size() % 2)
				{
					for (int i = 0; i < tmp.size(); i++)
						if (tmp[i] != tmp[0])
							ans = 0;
				}
				else
				{
					for (int i = 0; i < tmp.size(); i += 2)
						if (tmp[i] != tmp[0])
							ans = 0;
					for (int i = 1; i < tmp.size(); i += 2)
						if (tmp[i] != tmp[1])
							ans = 0;
				}
				return;
			}
			dfs(v, u);
			if (fd)
				return;
		}
}
int main()
{
	int TTT;
	yin >> TTT;
	for (int TT = 1; TT <= TTT; TT++)
	{
		yin >> n >> m;
		for (int i = 1; i <= n; i++)
			e[i].clear();
		for (int i = 1; i <= m; i++)
		{
			int u, v;
			yin >> u >> v;
			e[u].push_back(v);
			e[v].push_back(u);
		}
		if (m >= n + 1)
		{
			puts("NO");
			continue;
		}
		if (m == n - 1)
		{
			puts("YES");
			continue;
		}
		for (int i = 1; i <= n; i++)
			vis[i] = 0;
		// cerr << "!!!" << endl;
		if (TT == 35410)
		{
			cout << n << " " << m << endl;
		}
		ans = 1, fd = 0;
		dfs(1, 0);
		if (ans)
			puts("YES");
		else
			puts("NO");
	}
	return 0;
}