Implemented GeneratorEPOS4 test

MC/config/examples/ini/tests/GeneratorEPOS4.C

@@ -0,0 +1,64 @@
+int External()
+{
+  std::string path{"o2sim_Kine.root"};
+  // Check that file exists, can be opened and has the correct tree
+  TFile file(path.c_str(), "READ");
+  if (file.IsZombie())
+  {
+    std::cerr << "Cannot open ROOT file " << path << "\n";
+    return 1;
+  }
+  auto tree = (TTree *)file.Get("o2sim");
+  if (!tree)
+  {
+    std::cerr << "Cannot find tree o2sim in file " << path << "\n";
+    return 1;
+  }
+  std::vector<o2::MCTrack> *tracks{};
+  tree->SetBranchAddress("MCTrack", &tracks);
+
+  // Check if all events are filled
+  auto nEvents = tree->GetEntries();  
+  for (Long64_t i = 0; i < nEvents; ++i)
+  {
+    tree->GetEntry(i);
+    if (tracks->empty())
+    {
+      std::cerr << "Empty entry found at event " << i << "\n";
+      return 1;
+    }
+  }
+  // Check if there are 100 events, as simulated in the o2dpg-test
+  if (nEvents != 100)
+  {
+    std::cerr << "Expected 100 events, got " << nEvents << "\n";
+    return 1;
+  }
+  // check if each event has two protons with 6800 GeV of energy
+  // exits if the particle is not a proton 
+  for (int i = 0; i < nEvents; i++)
+  {
+    auto check = tree->GetEntry(i);
+    int count = 0;
+    for (int idxMCTrack = 0; idxMCTrack < tracks->size(); ++idxMCTrack)
+    {
+      auto track = tracks->at(idxMCTrack);
+      double energy = track.GetEnergy();
+      // Check if track energy is approximately equal to 6800 GeV (a tolerance of 65 keV is considered, straight equality does not work due to floating point precision)
+      if (std::abs(energy - 6800) < 1e-4) 
+      {
+        if (track.GetPdgCode() != 2212){
+          std::cerr << "Found 6800 GeV particle with pdgID " << track.GetPdgCode() << "\n";
+          return 1;
+        }         
+        count++;  
+      }
+    }
+    if (count < 2)
+    {
+      std::cerr << "Event " << i << " has less than 2 protons at 6800 GeV\n";
+      return 1;
+    }
+  }
+  return 0;
+}