[EMCAL-604] Initialize Unit Tests for the EMCal Geometry class (#13095)

- GetCellIndex as first function to be tested:
  - Check sm number, module number, phi and eta index for all valid cells
  - Check two exceptions for invalid cells
  - Check against on-the-fly calculation in the testGeometry.cxx file itself
- Minor correction in Geometry.cxx to improve readability of the code

Author: nstrangm

Detectors/EMCAL/base/CMakeLists.txt

@@ -42,6 +42,13 @@ o2_add_test(Mapper
         LABELS emcal
         ENVIRONMENT O2_ROOT=${CMAKE_BINARY_DIR}/stage)
 
+o2_add_test(Geometry
+        SOURCES test/testGeometry.cxx
+        PUBLIC_LINK_LIBRARIES O2::EMCALBase
+        COMPONENT_NAME emcal
+        LABELS emcal
+        ENVIRONMENT O2_ROOT=${CMAKE_BINARY_DIR}/stage)
+
 o2_add_test(RCUTrailer
         SOURCES test/testRCUTrailer.cxx
         PUBLIC_LINK_LIBRARIES O2::EMCALBase

Detectors/EMCAL/base/src/Geometry.cxx

@@ -1026,7 +1026,7 @@ std::tuple<int, int, int, int> Geometry::CalculateCellIndex(Int_t absId) const
 
   Int_t nModule = tmp / mNCellsInModule;
   tmp = tmp % mNCellsInModule;
-  Int_t nIphi = tmp / mNPHIdiv, nIeta = tmp % mNPHIdiv;
+  Int_t nIphi = tmp / mNPHIdiv, nIeta = tmp % mNETAdiv;
   return std::make_tuple(nSupMod, nModule, nIphi, nIeta);
 }
 

Detectors/EMCAL/base/test/testGeometry.cxx

@@ -0,0 +1,66 @@
+// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
+//
+// This software is distributed under the terms of the GNU General Public
+// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
+//
+// In applying this license CERN does not waive the privileges and immunities
+// granted to it by virtue of its status as an Intergovernmental Organization
+// or submit itself to any jurisdiction.
+#define BOOST_TEST_MODULE Test EMCAL Base
+#define BOOST_TEST_MAIN
+#define BOOST_TEST_DYN_LINK
+#include <boost/test/unit_test.hpp>
+#include <fmt/format.h>
+#include "EMCALBase/Geometry.h"
+#include <iostream>
+#include <fstream>
+
+std::tuple<int, int, int, int> GetRefCellIndex(int CellId);
+
+/// \macro Test implementation of the EMCAL Geometry
+///
+/// Test coverage:
+/// - GetCellIndex (get #sm, #mod, phi index and eta index): all cells (0-17663)
+/// - Invalid CellId: exception test for cell -1 and 17664
+BOOST_AUTO_TEST_CASE(Geometry_test)
+{
+  auto testgeometry = o2::emcal::Geometry::GetInstanceFromRunNumber(300000);
+
+  // Check GetCellIndex function for all valid cells by comparing to GetRefCellIndex function
+  for (int iCell = 0; iCell < 17664; iCell++) {
+    auto [smod, mod, iphi, ieta] = testgeometry->GetCellIndex(iCell);
+    auto [smod_ref, mod_ref, iphi_ref, ieta_ref] = GetRefCellIndex(iCell);
+    BOOST_CHECK_EQUAL(smod, smod_ref);
+    BOOST_CHECK_EQUAL(mod, mod_ref);
+    BOOST_CHECK_EQUAL(iphi, iphi_ref);
+    BOOST_CHECK_EQUAL(ieta, ieta_ref);
+  } // And then check the exeptions of -1 and 17664
+  BOOST_CHECK_EXCEPTION(testgeometry->GetCellIndex(-1), o2::emcal::InvalidCellIDException, [](o2::emcal::InvalidCellIDException const& mCellID) { return -1; });
+  BOOST_CHECK_EXCEPTION(testgeometry->GetCellIndex(17664), o2::emcal::InvalidCellIDException, [](o2::emcal::InvalidCellIDException const& mCellID) { return 17664; });
+}
+
+std::tuple<int, int, int, int> GetRefCellIndex(int CellId)
+{
+  // Four cells per module:
+  int ieta = CellId % 2;                                   // cells 0 and 2 (in each module) have eta index 0
+  int iphi = (CellId % 4 == 2 || CellId % 4 == 3) ? 1 : 0; // cells 0 and 1 (in each module) have phi index 0
+
+  int smod = 0, mod = 0;                          // Super module number and module number
+  if (CellId >= 0 && CellId < 11520) {            // The first 10 super modules are full modules
+    smod = CellId / 1152;                         // Their number is their cell number divided by the cells per sm (rounded down)
+    mod = (CellId % 1152) / 4;                    // And the module is the cell number within the sm (%) divided by four (four cells in one module)
+  } else if (CellId >= 11520 && CellId < 12288) { // First two one thirds
+    smod = 10 + (CellId - 11520) / 384;           // +10 to account for the - 11520
+    mod = ((CellId - 11520) % 384) / 4;           // -11520 to subtract all cells in full super modules
+  } else if (CellId >= 12288 && CellId < 16896) { // Six two third modules
+    smod = 12 + (CellId - 12288) / 768;
+    mod = ((CellId - 12288) % 768) / 4;
+  } else if (CellId >= 16896 && CellId < 17664) { // Second two one third modules
+    smod = 18 + (CellId - 16896) / 384;
+    mod = ((CellId - 16896) % 384) / 4;
+  }
+
+  return std::make_tuple(smod, mod, iphi, ieta);
+}