#include<bits/stdc++.h>

using namespace std;

using ull = unsigned long long;
constexpr int N = 1e6 + 10;
mt19937_64 rng(time(0));
ull rad = rng();
ull shift(ull x) {
    x ^= rad;
    x ^= x << 13;
    x ^= x >> 7;
    x ^= x << 17;
    x ^= rad;
    return x;
}
ull hs[N];
int sz[N], cnte[N], col[N];
vector<int>ver[N];
bool st[N];
void dfs1(int u, int fa) {
    hs[u] = 1, st[u] = 1;
    for (auto v : ver[u]) {
        if (st[v]) continue;
        dfs1(v, u);
        hs[u] += shift(hs[v]);
    }
}

struct EDCC {
    int n, now, cnt;

    vector<int>dfn, low, s;

    EDCC(int n) : n(n), low(n + 1) {
        for (int i = 1; i <= n; i++)ver[i].clear(), st[i] = 0, hs[i] = 0, col[i] = -1;
        dfn.resize(n + 1, -1);
        now = cnt = 0;
    }

    void add(int x, int y)
    {
        ver[x].push_back(y);
        ver[y].push_back(x);
    }

    void tarjan(int x, int fa)
    {
        dfn[x] = low[x] = now++;
        s.push_back(x);
        for (auto y : ver[x])
        {
            if (y == fa)continue;
            if (dfn[y] == -1) {
                tarjan(y, x);
                low[x] = min(low[x], low[y]);
            }
            else if (col[y] == -1 && dfn[y] < dfn[x])
            {
                low[x] = min(low[x], dfn[y]);
            }
        }
        if (dfn[x] == low[x])
        {
            int pre;
            cnt++;
            do {
                pre = s.back();
                col[pre] = cnt;
                s.pop_back();
            } while (pre != x);
        }
    }

    int work()
    {
        tarjan(1, 0);
        for (int i = 1; i <= cnt; i++)sz[cnt] = 0, cnte[i] = 0;
        for (int i = 1; i <= n; i++)
        {
            sz[col[i]]++;
            for (auto j : ver[i])
            {
                int x = col[i], y = col[j];
                if (x == y) {
                    cnte[x]++;
                }
            }
        }
        return cnt;
    }
};

vector<int>v;

void dfs(int u, int t)
{
    v.push_back(u), st[u] = 1;
    for (auto v : ver[u])
    {
        if (col[v] == t && !st[v])
        {
            dfs(v, t);
        }
    }
}

void solve() {
    int n, m; cin >> n >> m;
    EDCC e(n);
    while (m--) {
        int u, v; cin >> u >> v;
        e.add(u, v);
    }
    m = e.work();
    int j = 0;
    for (int i = 1; i <= m; i++)
    {
        if (sz[i] > 1) {
            if (j || cnte[i] / 2 != sz[i])
            {
                cout << "NO\n";
                return;
            }
            else j = i;
        }
    }
    if (!j)cout << "YES\n";
    else {

        v.clear();
        int u;
        for (int i = 1; i <= n; i++)
        {
            if (col[i] == j) {
                u = i;
                break;
            }
        }
        dfs(u, j);
        map<ull, int>ha; int tot = 0;
        for (auto k : v) {
            dfs1(k, 0);
            if (!ha.count(hs[k])) {
                ha[hs[k]] = tot++;
            }
        }
        if (tot > 2)cout << "NO\n";
        else if (tot == 1)
        {
            cout << "YES\n";
        }
        else {
            int op = ha[hs[v[0]]];
            for (auto k : v)
            {
                if (ha[hs[k]] != op) {
                    cout << "NO\n";
                    return;
                }
                op ^= 1;
            }
            cout << "YES\n";
        }
    }
}


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