#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
template <typename T> inline void read(T &F) {
    int R = 1; F = 0; char CH = getchar();
    for(; !isdigit(CH); CH = getchar()) if(CH == '-') R = -1;
    for(; isdigit(CH); CH = getchar()) F = F * 10 + CH - 48;
    F *= R;
}
inline void file(string str) {
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
}
const int N = 1e5 + 10;
int fa[N], now, fst[N], nxt[N << 1], num[N << 1], siz[N], g[N], R, n, m;
void add(int u, int v) {
    nxt[++now] = fst[u], fst[u] = now, num[now] = v;
    nxt[++now] = fst[v], fst[v] = now, num[now] = u;
}
unsigned long long f[N], pw[N];
const unsigned long long A = 1e9 + 7, B = 19260817, C = 2006;
unsigned long long h(unsigned long long x) {
    return A * x * x * x + B * x + C;
}
unsigned long long suan(unsigned long long x) {
    return h(x & ((1ull << 32) - 1)) + h(x >> 32);
}
void dfs(int x, int y) {
    f[x] = 1;
    for(int i = fst[x]; i; i = nxt[i]) {
        const int z = num[i];
        if(z == y) continue; dfs(z, x);
        f[x] += suan(f[z]);
    }
}
void calc(int x) {
    siz[x] = 1; g[x] = 0;
    for(int i = fst[x]; i; i = nxt[i]) {
        if(num[i] == fa[x]) continue;
        fa[num[i]] = x;
        calc(num[i]); siz[x] += siz[num[i]];
        g[x] = max(g[x], siz[num[i]]);
    }
    g[x] = max(g[x], n - siz[x]);
    if(g[x] < g[R]) R = x;
} 
int get_fa(int x) {
    return fa[x] == x ? x : fa[x] = get_fa(fa[x]);
}
pair<int, int> edge[N]; 
unsigned long long ran() {
    random_shuffle(edge + 1, edge + m + 1);
    for(int i = 1; i <= n + 1; i++) fst[i] = 0, fa[i] = i; now = 0;
    vector<pair<int, int> > e;
    for(int i = 1; i <= m; i++) {
        const int x = edge[i].first, y = edge[i].second;
        if(get_fa(x) == get_fa(y)) continue;
        e.emplace_back(x, y); add(x, y);
        fa[get_fa(x)] = get_fa(y);
    }
    fa[1] = R = 0; g[R] = 1e9;
    calc(1); int a = 0, b = 0, r = 0;
    if(g[R] == g[fa[R]]) a = R, b = fa[R], e.emplace_back(n + 1, a), e.emplace_back(n + 1, b), r = n + 1; else a = R, r = R;
    now = 0;
    for(int i = 1; i <= n + 1; i++) fst[i] = 0;
    for(auto i : e) {
        if((i.first == a && i.second == b) || (i.first == b && i.second == a)) continue;
        add(i.first, i.second);
    } 
    dfs(r, 0); return f[r];
}
int main() {
    //file("test");
    srand(time(0));
    int T; read(T);
    while(T--) {
        read(n), read(m);
        pw[0] = 1;
        for(int i = 1; i <= n + 1; i++) pw[i] = pw[i - 1] * B;
        for(int i = 1; i <= m; i++) read(edge[i].first), read(edge[i].second);
        unsigned long long G = ran(); int flag = 1;
        for(int i = 1; i <= 20; i++)
            if(ran() != G) {
                puts("NO"); flag = 0; break;
            }
        if(flag) puts("YES");
    }
    #ifdef _MagicDuck
        fprintf(stderr, "# Time: %.3lf s", (double)clock() / CLOCKS_PER_SEC);
    #endif
    return 0;
}