#include <bits/stdc++.h>
#pragma warning(disable : 4996)
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  long long t;
  cin >> t;
  while (t--) {
    long long n, m, x, y;
    cin >> n >> m >> x >> y;
    if (2 * x < y) y = 2 * x;
    vector<vector<long long>> grid(n, vector<long long>(m));
    for (long long i = 0; i < n; i++) {
      for (long long j = 0; j < m; j++) {
        char c;
        cin >> c;
        if (c == '.')
          grid[i][j] = 0;
        else
          grid[i][j] = 1;
      }
    }
    long long sum = 0;
    for (long long i = 0; i < n; i++) {
      vector<pair<long long, long long>> all;
      all.push_back({grid[i][0], 1});
      for (long long j = 1; j < m; j++) {
        if (grid[i][j] == all.back().first)
          all.back().second++;
        else
          all.push_back({grid[i][j], 1});
      }
      for (auto it : all) {
        if (it.first == 0) {
          long long a = it.second / 2, b = it.second % 2;
          sum += a * y;
          sum += b * x;
        }
      }
    }
    cout << sum << "\n";
  }
  return 0;
}
