#include <bits/stdc++.h>

typedef unsigned long long u64;

const int N = 100100;

int n, m;

int tot, head[N], ver[N * 2], Next[N * 2];
void add_edge(int u, int v) {
    ver[++ tot] = v;    Next[tot] = head[u];    head[u] = tot;
}

int dep[N];
int top, stk[N];
int seqlen, seq[N];
bool exist[N];

bool ok;
void dfs(int u, int fu) {
    if (ok) return;

    dep[u] = dep[fu] + 1;
    stk[++ top] = u;

    for (int i = head[u]; i; i = Next[i]) {
        int v = ver[i];
        if (v == fu) continue;

        if (!dep[v]) {
            dfs(v, u);
        } else if (dep[v] < dep[u]) {
            int x;
            do {
                x = stk[top --];
                seq[++ seqlen] = x;
            } while (x != v);

            ok = 1;
            return;
        }
    }

    top --;
}

u64 f[N];

u64 mask = std::mt19937_64((unsigned)time(0))();
u64 shift(u64 x) {
    x ^= mask;
    x ^= x << 13;
    x ^= x >> 7;
    x ^= x << 17;
    x ^= mask;
    return x;
}

void dfs_hash(int u, int fu) {
    f[u] = 1;
    for (int i = head[u]; i; i = Next[i]) {
        int v = ver[i];
        if (v == fu || exist[v]) continue;
        dfs_hash(v, u);
        f[u] += shift(f[v]);
    }
}

const u64 P = 13331;
u64 power[N];

u64 pre[N], pre_suf[N];
u64 suf[N], suf_pre[N];

void work() {
    scanf("%d%d", &n, &m);

    if (n == m) {
        tot = 0;
        for (int i = 1; i <= n; i ++) head[i] = 0;

        for (int i = 1, u, v; i <= m; i ++) {
            scanf("%d%d", &u, &v);
            add_edge(u, v), add_edge(v, u);
        }
    } else {
        for (int i = 1, u, v; i <= m; i ++)
            scanf("%d%d", &u, &v);
        if (m == n - 1)
            puts("YES");
        else
            puts("NO");
        return;
    }

    for (int i = 1; i <= n; i ++) dep[i] = 0;
    for (int i = 1; i <= n; i ++) exist[i] = 0;

    top = 0, seqlen = 0;
    ok = 0, dfs(1, 0);

    for (int i = 1; i <= seqlen; i ++) exist[seq[i]] = 1;

    for (int i = 1; i <= seqlen; i ++) dfs_hash(i, 0);

    power[0] = 1;
    for (int i = 1; i <= seqlen; i ++) power[i] = power[i - 1] * P;

    pre[0] = 0;
    for (int i = 1; i <= seqlen; i ++) pre[i] = pre[i - 1] * P + f[seq[i]];

    pre_suf[0] = 0;
    for (int i = 1; i <= seqlen; i ++) pre_suf[i] = pre_suf[i - 1] + power[i - 1] * f[seq[i]];

    suf[seqlen + 1] = 0;
    for (int i = seqlen; i >= 1; i --) suf[i] = suf[i + 1] * P + f[seq[i]];

    suf_pre[seqlen + 1] = 0;
    for (int i = seqlen; i >= 1; i --) suf_pre[i] = suf_pre[i + 1] + power[seqlen - i] * f[seq[i]];

    for (int i = 1; i <= seqlen; i ++)
        assert(pre[i] == suf[seqlen - i + 1]);

    for (int i = 1; i < seqlen; i ++) {
        u64 hash_pre = power[i] * suf_pre[i + 1] + pre[i];
        u64 hash_suf = power[seqlen - i] * pre_suf[i] + suf[i + 1];

        if (hash_pre == pre[seqlen] || hash_suf == pre[seqlen] || hash_pre == suf[1] || hash_suf == suf[1]);
        else {
            puts("NO");
            return;
        }
    }

    puts("YES");
}

int main() {
    int T;
    scanf("%d", &T);

    while (T --)
        work();

    return 0;
}