#include<bits/stdc++.h>
using std::cin, std::cout;
using u64 = unsigned long long;
const int mod = 1e9 + 7;
u64 k1, k2;
u64 xs128() {
	u64 k3 = k1, k4 = k2;
	k1 = k4;
	k3 ^= k3 << 23;
	k2 = k3 ^ k4 ^ (k3 >> 17) ^ (k4 >> 26);
	return k2 + k4;
}
const int N = 2000005;
int n, m;
struct edge { int u, v; u64 w; };
int anc[N];
int find(int x) {
	return anc[x] == x ? x : anc[x] = find(anc[x]);
}
int main() {
	std::ios::sync_with_stdio(false), cin.tie(0);
	int T; cin >> T;
	for(int i = 0;i < T;++i) {
		cin >> n >> m >> k1 >> k2;
		std::vector<edge> e(m);
		for(auto & [x, y, z] : e) {
			x = xs128() % n + 1;
			y = xs128() % n + 1;
			z = xs128();
		}
		sort(e.begin(), e.end(), [](auto & x, auto & y) { return x.w < y.w; });
		for(int i = 1;i < m;++i) {
			//assert(e[i].w != e[i - 1].w);
		}
		for(int i = 1;i <= n;++i) anc[i] = i;
		u64 sum = 0;
		int cnt = 1;
		for(auto [x, y, z] : e) {
			if(find(x) != find(y)) {
				anc[find(x)] = find(y);
				sum += z % mod;
				cnt += 1;
			}
		}
		if(cnt == n) {
			cout << sum % mod << '\n';
		} else {
			cout << 0 << '\n';
		}
	}
}