#include <bits/stdc++.h>
using namespace std;
template <typename T1, typename T2>
ostream &operator<<(ostream &os, pair<T1, T2> p) {
  os << p.first << " " << p.second;
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, vector<T> &v) {
  for (T i : v) os << i << ", ";
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, set<T> s) {
  for (T i : s) os << i << ", ";
  return os;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, map<T1, T2> m) {
  for (pair<T1, T2> i : m) os << i << endl;
  return os;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int t;
  cin >> t;
  while (t--) {
    int n, m, x, y;
    cin >> n >> m >> x >> y;
    string sq[n];
    int ans = 0;
    for (int i = 0; i < n; i++) {
      cin >> sq[i];
      for (int j = 0; j < m; j++) {
        if (sq[i][j] == '.') {
          if (y < 2 * x && j < m - 1 && sq[i][j + 1] == '.') {
            ans += y;
            j++;
          } else {
            ans += x;
          }
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}
