#include <bits/stdc++.h>
using namespace std;
void vin(vector<long long int> &v, long long int t) {
  for (long long int i = 0; i < t; i++) cin >> v[i];
}
void vout(vector<long long int> &v, long long int t) {
  for (long long int i = 0; i < t; i++) cout << v[i] << " ";
  cout << endl;
}
void ingraph(vector<vector<long long int>> &graph, long long int m) {
  long long int x, y;
  for (long long int i = 0; i < m; i++) {
    cin >> x >> y;
    x--, y--;
    graph[x].push_back(y);
    graph[y].push_back(x);
  }
}
bool sortbysec(const pair<int, int> &a, const pair<int, int> &b) {
  return (a.second < b.second);
}
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int lcm(long long int a, long long int b) {
  return a * b / gcd(a, b);
}
void solve() {
  long long int n, m, x, y;
  cin >> n >> m >> x >> y;
  long long int cost = 0;
  y = min(y, 2 * x);
  for (long long int i = 0; i < n; i++) {
    string s;
    cin >> s;
    for (long long int j = 0; j < m; j++) {
      if (s[j] == '.') {
        if (j != m - 1 && s[j + 1] == '.')
          cost += y, j++;
        else
          cost += x;
      }
    }
  }
  cout << cost << "\n";
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long int t;
  cin >> t;
  while (t--) solve();
  return 0;
}
