#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], B;
const unsigned long long A = 1e9 + 9, C = 97; 
unsigned long long h(unsigned long long x) {
    return A * x * x * x + C;
}
unsigned long long suan(unsigned long long x) {
    return h(x & ((1ull << 32) - 1)) + h(x >> 32);
}
LL seed = chrono :: steady_clock :: now().time_since_epoch().count();
mt19937_64 rnd(seed);
void dfs(int x) {
    f[x] = B;
    for(int i = fst[x]; i; i = nxt[i]) {
        const int z = num[i];
        if(z == fa[x]) continue;
        fa[z] = x; dfs(z); f[x] += suan(f[z]);
    }
}
void calc(int x) {
    siz[x] = 1; g[x] = 0;
    for(int i = fst[x]; i; i = nxt[i]) {
        const int y = num[i];
        if(y == fa[x]) continue;
        fa[y] = x; calc(y); siz[x] += siz[y];
        g[x] = max(g[x], siz[y]);
    }
    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;
    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;
        add(x, y);
        fa[get_fa(x)] = get_fa(y);
    }
    fa[1] = R = 0; g[R] = 1e9; fa[n + 1] = 0;
    calc(1); if(g[R] == g[fa[R]]) fa[R] = n + 1, fa[n + 1] = R, R = n + 1;
    now = 0; memset(fst, 0, sizeof(fst));
    for(int i = 1; i <= n + 1; i++) if(fa[i]) add(i, fa[i]);
    fa[R] = 0; dfs(R); return f[R];
}
int main() {
    //file("test");
    srand(time(0));
    int T; read(T);
    while(T--) {
        read(n), read(m); B = rnd();
        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 <= 30; 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;
}