Added missing md5 hash test code

Author: Martin D. Weinberg

utils/Test/testmd5.cc

@@ -0,0 +1,48 @@
+// This test verifies that QuickDigest5 correctly computes the MD5
+// hash of a file
+
+#include <iostream>
+#include <filesystem>
+
+#include "quickdigest5.hpp"
+
+#include "exputils.H" // For get_md5sum which uses the system's md5sum
+		      // command for verification
+
+int main(int argc, char* argv[])
+{
+  // Default to example.txt if no argument
+  std::string filePath = argc > 1 ? argv[1] : "example.txt";
+
+  // Check if the file exists before trying to hash it
+  std::filesystem::path p(filePath);
+  if (!std::filesystem::exists(p)) {
+    std::cout << "File <" << filePath << "> not found." << std::endl
+	      << "Usage: " << argv[0] << " [file_path]" << std::endl
+	      << "Defaulting to example.txt if it exists." << std::endl;
+  }
+
+  // One-line method to get the hex digest of a file
+  std::string hash = QuickDigest5::fileToHash(filePath);
+
+  if (!hash.empty()) {
+    std::cout << "MD5: " << hash << std::endl;
+  } else {
+    std::cerr << "Error: Could not process file." << std::endl;
+  }
+  
+  // System version of md5sum for comparison
+  try {
+    std::string systemHash = get_md5sum(filePath);
+    std::cout << "System md5sum: " << systemHash << std::endl;
+    if (hash == systemHash) {
+      std::cout << "Success: hashes match!" << std::endl;
+    } else {
+      std::cerr << "Error: hashes do not match!" << std::endl;
+    }
+  } catch (const std::exception& e) {
+    std::cerr << "Error computing system md5sum: " << e.what() << std::endl;
+  }
+
+  return 0;
+}