From d29e3097c152bbb703ad4e3502eda0ea80dd71c2 Mon Sep 17 00:00:00 2001
From: Thomas Madlener <thomas.madlener@desy.de>
Date: Thu, 5 Oct 2023 12:19:55 +0200
Subject: [PATCH] Unified converter maps (#147)

* Make object map names consistent in both directions

* Add a global map to keep state across several conversions

* Use TES to move global map between tools instead of singleton

* Pass the global maps to subset and association coll conversions

* Add isolated test case for the global converter maps

* Add brief description of new test case
---
 k4MarlinWrapper/examples/clicRec_e4h_input.py |   3 +
 .../k4MarlinWrapper/converters/EDM4hep2Lcio.h |  79 +++++------
 .../src/components/EDM4hep2Lcio.cpp           | 133 +++++++++++-------
 .../components/GlobalConvertedObjectsMap.h    | 124 ++++++++++++++++
 .../src/components/Lcio2EDM4hep.cpp           |  56 +++++++-
 test/CMakeLists.txt                           |  25 +++-
 test/README.md                                |  57 ++++++++
 test/gaudi_opts/test_global_converter_maps.py |  95 +++++++++++++
 test/scripts/global_converter_maps.sh         |  31 ++++
 test/src/MCRecoLinkChecker.cc                 |  71 ++++++++++
 test/src/MCRecoLinkChecker.h                  |  46 ++++++
 test/src/PseudoRecoProcessor.cc               |  52 +++++++
 test/src/PseudoRecoProcessor.h                |  37 +++++
 test/src/TrivialMCTruthLinkerProcessor.cc     |  58 ++++++++
 test/src/TrivialMCTruthLinkerProcessor.h      |  38 +++++
 15 files changed, 807 insertions(+), 98 deletions(-)
 create mode 100644 k4MarlinWrapper/src/components/GlobalConvertedObjectsMap.h
 create mode 100644 test/README.md
 create mode 100644 test/gaudi_opts/test_global_converter_maps.py
 create mode 100644 test/scripts/global_converter_maps.sh
 create mode 100644 test/src/MCRecoLinkChecker.cc
 create mode 100644 test/src/MCRecoLinkChecker.h
 create mode 100644 test/src/PseudoRecoProcessor.cc
 create mode 100644 test/src/PseudoRecoProcessor.h
 create mode 100644 test/src/TrivialMCTruthLinkerProcessor.cc
 create mode 100644 test/src/TrivialMCTruthLinkerProcessor.h

diff --git a/k4MarlinWrapper/examples/clicRec_e4h_input.py b/k4MarlinWrapper/examples/clicRec_e4h_input.py
index 94d6e4b0..f83664f9 100644
--- a/k4MarlinWrapper/examples/clicRec_e4h_input.py
+++ b/k4MarlinWrapper/examples/clicRec_e4h_input.py
@@ -1722,6 +1722,9 @@
   "BuildUpVertices_V0": "BuildUpVertices_V0",
   "BuildUpVertices": "BuildUpVertices",
   "PrimaryVertices": "PrimaryVertices",
+  "BuildUpVertices_RP": "BuildUpVertices_RP",
+  "BuildUpVertices_V0_RP": "BuildUpVertices_V0_RP",
+  "PrimaryVertices_RP": "PrimaryVertices_RP",
   }
 VertexFinderLCIOConv.OutputLevel = DEBUG
 # Add it to VertexFinder Algorithm
diff --git a/k4MarlinWrapper/k4MarlinWrapper/converters/EDM4hep2Lcio.h b/k4MarlinWrapper/k4MarlinWrapper/converters/EDM4hep2Lcio.h
index b0ee251b..c3d3a05e 100644
--- a/k4MarlinWrapper/k4MarlinWrapper/converters/EDM4hep2Lcio.h
+++ b/k4MarlinWrapper/k4MarlinWrapper/converters/EDM4hep2Lcio.h
@@ -34,12 +34,24 @@
 // std
 #include <map>
 #include <string>
+#include <tuple>
 #include <vector>
 
-#ifdef EDM4HEP2LCIOCONV_NAMESPACE
-using EDM4hep2LCIOConv::CollectionsPairVectors;
-using EDM4hep2LCIOConv::vec_pair;
-#endif
+template <typename K, typename V> using ObjMapT = k4EDM4hep2LcioConv::VecMapT<K, V>;
+
+using TrackMap         = ObjMapT<lcio::TrackImpl*, edm4hep::Track>;
+using ClusterMap       = ObjMapT<lcio::ClusterImpl*, edm4hep::Cluster>;
+using VertexMap        = ObjMapT<lcio::VertexImpl*, edm4hep::Vertex>;
+using TrackerHitMap    = ObjMapT<lcio::TrackerHitImpl*, edm4hep::TrackerHit>;
+using SimTrackerHitMap = ObjMapT<lcio::SimTrackerHitImpl*, edm4hep::SimTrackerHit>;
+using CaloHitMap       = ObjMapT<lcio::CalorimeterHitImpl*, edm4hep::CalorimeterHit>;
+using SimCaloHitMap    = ObjMapT<lcio::SimCalorimeterHitImpl*, edm4hep::SimCalorimeterHit>;
+using RawCaloHitMap    = ObjMapT<lcio::RawCalorimeterHitImpl*, edm4hep::RawCalorimeterHit>;
+using TPCHitMap        = ObjMapT<lcio::TPCHitImpl*, edm4hep::RawTimeSeries>;
+using RecoParticleMap  = ObjMapT<lcio::ReconstructedParticleImpl*, edm4hep::ReconstructedParticle>;
+using MCParticleMap    = ObjMapT<lcio::MCParticleImpl*, edm4hep::MCParticle>;
+
+struct CollectionPairMappings;
 
 class EDM4hep2LcioTool : public GaudiTool, virtual public IEDMConverter {
 public:
@@ -57,62 +69,47 @@ class EDM4hep2LcioTool : public GaudiTool, virtual public IEDMConverter {
   PodioDataSvc*                   m_podioDataSvc;
   ServiceHandle<IDataProviderSvc> m_eventDataSvc;
 
-  void convertTracks(vec_pair<lcio::TrackImpl*, edm4hep::Track>&           tracks_vec,
-                     vec_pair<lcio::TrackerHitImpl*, edm4hep::TrackerHit>& trackerhits_vec,
-                     const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                     lcio::LCEventImpl* lcio_event);
+  void convertTracks(TrackMap& tracks_vec, const TrackerHitMap& trackerhits_vec, const std::string& e4h_coll_name,
+                     const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event);
 
-  void convertTrackerHits(vec_pair<lcio::TrackerHitImpl*, edm4hep::TrackerHit>& trackerhits_vec,
-                          const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                          lcio::LCEventImpl* lcio_event);
+  void convertTrackerHits(TrackerHitMap& trackerhits_vec, const std::string& e4h_coll_name,
+                          const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event);
 
-  void convertSimTrackerHits(vec_pair<lcio::SimTrackerHitImpl*, edm4hep::SimTrackerHit>& simtrackerhits_vec,
-                             const vec_pair<lcio::MCParticleImpl*, edm4hep::MCParticle>& mcparticles_vec,
+  void convertSimTrackerHits(SimTrackerHitMap& simtrackerhits_vec, const MCParticleMap& mcparticles_vec,
                              const std::string& e4h_coll_name, const std::string& lcio_coll_name,
                              lcio::LCEventImpl* lcio_event);
 
-  void convertCalorimeterHits(vec_pair<lcio::CalorimeterHitImpl*, edm4hep::CalorimeterHit>& calo_hits_vec,
-                              const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                              lcio::LCEventImpl* lcio_event);
+  void convertCalorimeterHits(CaloHitMap& calo_hits_vec, const std::string& e4h_coll_name,
+                              const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event);
 
-  void convertRawCalorimeterHits(vec_pair<lcio::RawCalorimeterHitImpl*, edm4hep::RawCalorimeterHit>& raw_calo_hits_vec,
-                                 const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                                 lcio::LCEventImpl* lcio_event);
+  void convertRawCalorimeterHits(RawCaloHitMap& raw_calo_hits_vec, const std::string& e4h_coll_name,
+                                 const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event);
 
-  void convertSimCalorimeterHits(vec_pair<lcio::SimCalorimeterHitImpl*, edm4hep::SimCalorimeterHit>& sim_calo_hits_vec,
-                                 const vec_pair<lcio::MCParticleImpl*, edm4hep::MCParticle>&         mcparticles,
+  void convertSimCalorimeterHits(SimCaloHitMap& sim_calo_hits_vec, const MCParticleMap& mcparticles,
                                  const std::string& e4h_coll_name, const std::string& lcio_coll_name,
                                  lcio::LCEventImpl* lcio_event);
 
-  void convertTPCHits(vec_pair<lcio::TPCHitImpl*, edm4hep::RawTimeSeries>& tpc_hits_vec,
-                      const std::string& e4h_coll_name, const std::string& lcio_coll_name,
+  void convertTPCHits(TPCHitMap& tpc_hits_vec, const std::string& e4h_coll_name, const std::string& lcio_coll_name,
                       lcio::LCEventImpl* lcio_event);
 
-  void convertClusters(vec_pair<lcio::ClusterImpl*, edm4hep::Cluster>&                     cluster_vec,
-                       const vec_pair<lcio::CalorimeterHitImpl*, edm4hep::CalorimeterHit>& calohits_vec,
-                       const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                       lcio::LCEventImpl* lcio_event);
+  void convertClusters(ClusterMap& cluster_vec, const CaloHitMap& calohits_vec, const std::string& e4h_coll_name,
+                       const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event);
 
-  void convertVertices(
-      vec_pair<lcio::VertexImpl*, edm4hep::Vertex>&                                     vertex_vec,
-      const vec_pair<lcio::ReconstructedParticleImpl*, edm4hep::ReconstructedParticle>& recoparticles_vec,
-      const std::string& e4h_name, const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event);
+  void convertVertices(VertexMap& vertex_vec, const RecoParticleMap& recoparticles_vec, const std::string& e4h_name,
+                       const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event);
 
-  void convertReconstructedParticles(
-      vec_pair<lcio::ReconstructedParticleImpl*, edm4hep::ReconstructedParticle>& recoparticles_vec,
-      const vec_pair<lcio::TrackImpl*, edm4hep::Track>&                           tracks_vec,
-      const vec_pair<lcio::VertexImpl*, edm4hep::Vertex>&                         vertex_vec,
-      const vec_pair<lcio::ClusterImpl*, edm4hep::Cluster>& clusters_vec, const std::string& e4h_coll_name,
-      const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event);
+  void convertReconstructedParticles(RecoParticleMap& recoparticles_vec, const TrackMap& tracks_vec,
+                                     const VertexMap& vertex_vec, const ClusterMap& clusters_vec,
+                                     const std::string& e4h_coll_name, const std::string& lcio_coll_name,
+                                     lcio::LCEventImpl* lcio_event);
 
-  void convertMCParticles(vec_pair<lcio::MCParticleImpl*, edm4hep::MCParticle>& mc_particles_vec,
-                          const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                          lcio::LCEventImpl* lcio_event);
+  void convertMCParticles(MCParticleMap& mc_particles_vec, const std::string& e4h_coll_name,
+                          const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event);
 
   void convertEventHeader(const std::string& e4h_coll_name, lcio::LCEventImpl* lcio_event);
 
   void convertAdd(const std::string& e4h_coll_name, const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event,
-                  CollectionsPairVectors& collection_pairs);
+                  CollectionPairMappings& collection_pairs);
 };
 
 #endif
diff --git a/k4MarlinWrapper/src/components/EDM4hep2Lcio.cpp b/k4MarlinWrapper/src/components/EDM4hep2Lcio.cpp
index 3083e266..6d16d05f 100644
--- a/k4MarlinWrapper/src/components/EDM4hep2Lcio.cpp
+++ b/k4MarlinWrapper/src/components/EDM4hep2Lcio.cpp
@@ -17,16 +17,39 @@
  * limitations under the License.
  */
 #include "k4MarlinWrapper/converters/EDM4hep2Lcio.h"
+#include "GlobalConvertedObjectsMap.h"
 
 #include "k4FWCore/DataHandle.h"
 #include "k4FWCore/MetaDataHandle.h"
 
+#include "GaudiKernel/AnyDataWrapper.h"
+
+#include <memory>
+
 DECLARE_COMPONENT(EDM4hep2LcioTool);
 
 #ifdef EDM4HEP2LCIOCONV_NAMESPACE
 using namespace EDM4hep2LCIOConv;
 #endif
 
+using namespace k4MarlinWrapper;
+
+using GlobalMapWrapper = AnyDataWrapper<GlobalConvertedObjectsMap>;
+
+struct CollectionPairMappings {
+  TrackMap         tracks{};
+  TrackerHitMap    trackerHits{};
+  SimTrackerHitMap simTrackerHits{};
+  CaloHitMap       caloHits{};
+  RawCaloHitMap    rawCaloHits{};
+  SimCaloHitMap    simCaloHits{};
+  TPCHitMap        tpcHits{};
+  ClusterMap       clusters{};
+  VertexMap        vertices{};
+  RecoParticleMap  recoParticles{};
+  MCParticleMap    mcParticles{};
+};
+
 EDM4hep2LcioTool::EDM4hep2LcioTool(const std::string& type, const std::string& name, const IInterface* parent)
     : GaudiTool(type, name, parent), m_eventDataSvc("EventDataSvc", "EDM4hep2LcioTool") {
   declareInterface<IEDMConverter>(this);
@@ -51,8 +74,7 @@ StatusCode EDM4hep2LcioTool::finalize() { return GaudiTool::finalize(); }
 // Convert EDM4hep Tracks to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertTracks(vec_pair<lcio::TrackImpl*, edm4hep::Track>&           tracks_vec,
-                                     vec_pair<lcio::TrackerHitImpl*, edm4hep::TrackerHit>& trackerhits_vec,
+void EDM4hep2LcioTool::convertTracks(TrackMap& tracks_vec, const TrackerHitMap& trackerhits_vec,
                                      const std::string& e4h_coll_name, const std::string& lcio_coll_name,
                                      lcio::LCEventImpl* lcio_event) {
   DataHandle<edm4hep::TrackCollection> tracks_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
@@ -67,9 +89,8 @@ void EDM4hep2LcioTool::convertTracks(vec_pair<lcio::TrackImpl*, edm4hep::Track>&
 // Convert EDM4hep TrackerHits to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertTrackerHits(vec_pair<lcio::TrackerHitImpl*, edm4hep::TrackerHit>& trackerhits_vec,
-                                          const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                                          lcio::LCEventImpl* lcio_event) {
+void EDM4hep2LcioTool::convertTrackerHits(TrackerHitMap& trackerhits_vec, const std::string& e4h_coll_name,
+                                          const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
   DataHandle<edm4hep::TrackerHitCollection> trackerhits_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
   const auto                                trackerhits_coll = trackerhits_handle.get();
 
@@ -84,10 +105,9 @@ void EDM4hep2LcioTool::convertTrackerHits(vec_pair<lcio::TrackerHitImpl*, edm4he
 // Convert EDM4hep SimTrackerHits to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertSimTrackerHits(
-    vec_pair<lcio::SimTrackerHitImpl*, edm4hep::SimTrackerHit>& simtrackerhits_vec,
-    const vec_pair<lcio::MCParticleImpl*, edm4hep::MCParticle>& mcparticles_vec, const std::string& e4h_coll_name,
-    const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
+void EDM4hep2LcioTool::convertSimTrackerHits(SimTrackerHitMap& simtrackerhits_vec, const MCParticleMap& mcparticles_vec,
+                                             const std::string& e4h_coll_name, const std::string& lcio_coll_name,
+                                             lcio::LCEventImpl* lcio_event) {
   DataHandle<edm4hep::SimTrackerHitCollection> simtrackerhits_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
   const auto                                   simtrackerhits_coll = simtrackerhits_handle.get();
 
@@ -103,9 +123,8 @@ void EDM4hep2LcioTool::convertSimTrackerHits(
 // Convert EDM4hep Calorimeter Hits to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add converted LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertCalorimeterHits(
-    vec_pair<lcio::CalorimeterHitImpl*, edm4hep::CalorimeterHit>& calo_hits_vec, const std::string& e4h_coll_name,
-    const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
+void EDM4hep2LcioTool::convertCalorimeterHits(CaloHitMap& calo_hits_vec, const std::string& e4h_coll_name,
+                                              const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
   DataHandle<edm4hep::CalorimeterHitCollection> calohit_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
   const auto                                    calohit_coll = calohit_handle.get();
 
@@ -121,9 +140,8 @@ void EDM4hep2LcioTool::convertCalorimeterHits(
 // Convert EDM4hep RAW Calorimeter Hits to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add converted LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertRawCalorimeterHits(
-    vec_pair<lcio::RawCalorimeterHitImpl*, edm4hep::RawCalorimeterHit>& raw_calo_hits_vec,
-    const std::string& e4h_coll_name, const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
+void EDM4hep2LcioTool::convertRawCalorimeterHits(RawCaloHitMap& raw_calo_hits_vec, const std::string& e4h_coll_name,
+                                                 const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
   DataHandle<edm4hep::RawCalorimeterHitCollection> raw_calohit_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
   const auto                                       rawcalohit_coll = raw_calohit_handle.get();
 
@@ -136,10 +154,9 @@ void EDM4hep2LcioTool::convertRawCalorimeterHits(
 // Convert EDM4hep Sim Calorimeter Hits to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add converted LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertSimCalorimeterHits(
-    vec_pair<lcio::SimCalorimeterHitImpl*, edm4hep::SimCalorimeterHit>& sim_calo_hits_vec,
-    const vec_pair<lcio::MCParticleImpl*, edm4hep::MCParticle>& mcparticles, const std::string& e4h_coll_name,
-    const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
+void EDM4hep2LcioTool::convertSimCalorimeterHits(SimCaloHitMap& sim_calo_hits_vec, const MCParticleMap& mcparticles,
+                                                 const std::string& e4h_coll_name, const std::string& lcio_coll_name,
+                                                 lcio::LCEventImpl* lcio_event) {
   DataHandle<edm4hep::SimCalorimeterHitCollection> sim_calohit_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
   const auto                                       simcalohit_coll = sim_calohit_handle.get();
 
@@ -156,9 +173,8 @@ void EDM4hep2LcioTool::convertSimCalorimeterHits(
 // Convert EDM4hep TPC Hits to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add converted LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertTPCHits(vec_pair<lcio::TPCHitImpl*, edm4hep::RawTimeSeries>& tpc_hits_vec,
-                                      const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                                      lcio::LCEventImpl* lcio_event) {
+void EDM4hep2LcioTool::convertTPCHits(TPCHitMap& tpc_hits_vec, const std::string& e4h_coll_name,
+                                      const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
   DataHandle<edm4hep::RawTimeSeriesCollection> tpchit_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
   const auto                                   tpchit_coll = tpchit_handle.get();
 
@@ -171,8 +187,7 @@ void EDM4hep2LcioTool::convertTPCHits(vec_pair<lcio::TPCHitImpl*, edm4hep::RawTi
 // Convert EDM4hep Clusters to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add converted LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertClusters(vec_pair<lcio::ClusterImpl*, edm4hep::Cluster>&                     cluster_vec,
-                                       const vec_pair<lcio::CalorimeterHitImpl*, edm4hep::CalorimeterHit>& calohits_vec,
+void EDM4hep2LcioTool::convertClusters(ClusterMap& cluster_vec, const CaloHitMap& calohits_vec,
                                        const std::string& e4h_coll_name, const std::string& lcio_coll_name,
                                        lcio::LCEventImpl* lcio_event) {
   DataHandle<edm4hep::ClusterCollection> cluster_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
@@ -187,10 +202,9 @@ void EDM4hep2LcioTool::convertClusters(vec_pair<lcio::ClusterImpl*, edm4hep::Clu
 // Convert EDM4hep Vertices to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add converted LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertVertices(
-    vec_pair<lcio::VertexImpl*, edm4hep::Vertex>&                                     vertex_vec,
-    const vec_pair<lcio::ReconstructedParticleImpl*, edm4hep::ReconstructedParticle>& recoparticles_vec,
-    const std::string& e4h_coll_name, const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
+void EDM4hep2LcioTool::convertVertices(VertexMap& vertex_vec, const RecoParticleMap& recoparticles_vec,
+                                       const std::string& e4h_coll_name, const std::string& lcio_coll_name,
+                                       lcio::LCEventImpl* lcio_event) {
   DataHandle<edm4hep::VertexCollection> vertex_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
   const auto                            vertex_coll = vertex_handle.get();
 
@@ -203,9 +217,8 @@ void EDM4hep2LcioTool::convertVertices(
 // Convert MC Particles to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add converted LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertMCParticles(vec_pair<lcio::MCParticleImpl*, edm4hep::MCParticle>& mc_particles_vec,
-                                          const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                                          lcio::LCEventImpl* lcio_event) {
+void EDM4hep2LcioTool::convertMCParticles(MCParticleMap& mc_particles_vec, const std::string& e4h_coll_name,
+                                          const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
   // MCParticles handle
   DataHandle<edm4hep::MCParticleCollection> mcparticle_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
   const auto                                mcparticle_coll = mcparticle_handle.get();
@@ -219,12 +232,10 @@ void EDM4hep2LcioTool::convertMCParticles(vec_pair<lcio::MCParticleImpl*, edm4he
 // Convert EDM4hep RecoParticles to LCIO
 // Add converted LCIO ptr and original EDM4hep collection to vector of pairs
 // Add converted LCIO Collection Vector to LCIO event
-void EDM4hep2LcioTool::convertReconstructedParticles(
-    vec_pair<lcio::ReconstructedParticleImpl*, edm4hep::ReconstructedParticle>& recoparticles_vec,
-    const vec_pair<lcio::TrackImpl*, edm4hep::Track>&                           tracks_vec,
-    const vec_pair<lcio::VertexImpl*, edm4hep::Vertex>&                         vertex_vec,
-    const vec_pair<lcio::ClusterImpl*, edm4hep::Cluster>& clusters_vec, const std::string& e4h_coll_name,
-    const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
+void EDM4hep2LcioTool::convertReconstructedParticles(RecoParticleMap& recoparticles_vec, const TrackMap& tracks_vec,
+                                                     const VertexMap& vertex_vec, const ClusterMap& clusters_vec,
+                                                     const std::string& e4h_coll_name,
+                                                     const std::string& lcio_coll_name, lcio::LCEventImpl* lcio_event) {
   // ReconstructedParticles handle
   DataHandle<edm4hep::ReconstructedParticleCollection> recos_handle{e4h_coll_name, Gaudi::DataHandle::Reader, this};
   const auto                                           recos_coll = recos_handle.get();
@@ -249,7 +260,7 @@ void EDM4hep2LcioTool::convertEventHeader(const std::string& e4h_coll_name, lcio
 
 // Select the appropiate method to convert a collection given its type
 void EDM4hep2LcioTool::convertAdd(const std::string& e4h_coll_name, const std::string& lcio_coll_name,
-                                  lcio::LCEventImpl* lcio_event, CollectionsPairVectors& collection_pairs) {
+                                  lcio::LCEventImpl* lcio_event, CollectionPairMappings& collection_pairs) {
   const auto& evtFrame = m_podioDataSvc->getEventFrame();
   const auto  collPtr  = evtFrame.get(e4h_coll_name);
   if (!collPtr) {
@@ -257,31 +268,33 @@ void EDM4hep2LcioTool::convertAdd(const std::string& e4h_coll_name, const std::s
   }
   const auto fulltype = collPtr->getValueTypeName();
 
+  debug() << "Converting type " << fulltype << " from input " << e4h_coll_name << endmsg;
+
   if (fulltype == "edm4hep::Track") {
-    convertTracks(collection_pairs.tracks, collection_pairs.trackerhits, e4h_coll_name, lcio_coll_name, lcio_event);
+    convertTracks(collection_pairs.tracks, collection_pairs.trackerHits, e4h_coll_name, lcio_coll_name, lcio_event);
   } else if (fulltype == "edm4hep::TrackerHit") {
-    convertTrackerHits(collection_pairs.trackerhits, e4h_coll_name, lcio_coll_name, lcio_event);
+    convertTrackerHits(collection_pairs.trackerHits, e4h_coll_name, lcio_coll_name, lcio_event);
   } else if (fulltype == "edm4hep::SimTrackerHit") {
-    convertSimTrackerHits(collection_pairs.simtrackerhits, collection_pairs.mcparticles, e4h_coll_name, lcio_coll_name,
+    convertSimTrackerHits(collection_pairs.simTrackerHits, collection_pairs.mcParticles, e4h_coll_name, lcio_coll_name,
                           lcio_event);
   } else if (fulltype == "edm4hep::CalorimeterHit") {
-    convertCalorimeterHits(collection_pairs.calohits, e4h_coll_name, lcio_coll_name, lcio_event);
+    convertCalorimeterHits(collection_pairs.caloHits, e4h_coll_name, lcio_coll_name, lcio_event);
   } else if (fulltype == "edm4hep::RawCalorimeterHit") {
-    convertRawCalorimeterHits(collection_pairs.rawcalohits, e4h_coll_name, lcio_coll_name, lcio_event);
+    convertRawCalorimeterHits(collection_pairs.rawCaloHits, e4h_coll_name, lcio_coll_name, lcio_event);
   } else if (fulltype == "edm4hep::SimCalorimeterHit") {
-    convertSimCalorimeterHits(collection_pairs.simcalohits, collection_pairs.mcparticles, e4h_coll_name, lcio_coll_name,
+    convertSimCalorimeterHits(collection_pairs.simCaloHits, collection_pairs.mcParticles, e4h_coll_name, lcio_coll_name,
                               lcio_event);
   } else if (fulltype == "edm4hep::RawTimeSeries") {
-    convertTPCHits(collection_pairs.tpchits, e4h_coll_name, lcio_coll_name, lcio_event);
+    convertTPCHits(collection_pairs.tpcHits, e4h_coll_name, lcio_coll_name, lcio_event);
   } else if (fulltype == "edm4hep::Cluster") {
-    convertClusters(collection_pairs.clusters, collection_pairs.calohits, e4h_coll_name, lcio_coll_name, lcio_event);
+    convertClusters(collection_pairs.clusters, collection_pairs.caloHits, e4h_coll_name, lcio_coll_name, lcio_event);
   } else if (fulltype == "edm4hep::Vertex") {
-    convertVertices(collection_pairs.vertices, collection_pairs.recoparticles, e4h_coll_name, lcio_coll_name,
+    convertVertices(collection_pairs.vertices, collection_pairs.recoParticles, e4h_coll_name, lcio_coll_name,
                     lcio_event);
   } else if (fulltype == "edm4hep::MCParticle") {
-    convertMCParticles(collection_pairs.mcparticles, e4h_coll_name, lcio_coll_name, lcio_event);
+    convertMCParticles(collection_pairs.mcParticles, e4h_coll_name, lcio_coll_name, lcio_event);
   } else if (fulltype == "edm4hep::ReconstructedParticle") {
-    convertReconstructedParticles(collection_pairs.recoparticles, collection_pairs.tracks, collection_pairs.vertices,
+    convertReconstructedParticles(collection_pairs.recoParticles, collection_pairs.tracks, collection_pairs.vertices,
                                   collection_pairs.clusters, e4h_coll_name, lcio_coll_name, lcio_event);
   } else if (fulltype == "edm4hep::EventHeader") {
     convertEventHeader(e4h_coll_name, lcio_event);
@@ -313,8 +326,9 @@ StatusCode EDM4hep2LcioTool::convertCollections(lcio::LCEventImpl* lcio_event) {
     }
   }
 
-  CollectionsPairVectors collection_pairs{};
+  CollectionPairMappings collection_pairs{};
   for (const auto& [edm4hepName, lcioName] : collsToConvert) {
+    debug() << "Converting collection " << edm4hepName << " (storing it as " << lcioName << ")" << endmsg;
     if (!collectionExist(lcioName, lcio_event)) {
       convertAdd(edm4hepName, lcioName, lcio_event, collection_pairs);
     } else {
@@ -324,7 +338,24 @@ StatusCode EDM4hep2LcioTool::convertCollections(lcio::LCEventImpl* lcio_event) {
 
   debug() << "Event: " << lcio_event->getEventNumber() << " Run: " << lcio_event->getRunNumber() << endmsg;
 
-  FillMissingCollections(collection_pairs);
+  // We want one "global" map that is created the first time it is use in the
+  // event.
+  //
+  // Technically getOrCreate is a thing in GaudiTool but that doesn't seem to
+  // easily work with the AnyDataWrapper we want to use here. So doing the two
+  // step process here
+  if (!exist<GlobalMapWrapper>(GlobalConvertedObjectsMap::TESpath.data())) {
+    debug() << "Creating GlobalconvertedObjectsMap for this event since it is not already in the EventStore" << endmsg;
+    auto globalObjMapWrapper = std::make_unique<GlobalMapWrapper>(GlobalConvertedObjectsMap{});
+    put(std::move(globalObjMapWrapper), GlobalConvertedObjectsMap::TESpath.data());
+  }
+
+  auto  globalObjMapWrapper = get<GlobalMapWrapper>(GlobalConvertedObjectsMap::TESpath.data());
+  auto& globalObjMap        = globalObjMapWrapper->getData();
+
+  globalObjMap.update(collection_pairs);
+
+  FillMissingCollections(collection_pairs, globalObjMap);
 
   return StatusCode::SUCCESS;
 }
diff --git a/k4MarlinWrapper/src/components/GlobalConvertedObjectsMap.h b/k4MarlinWrapper/src/components/GlobalConvertedObjectsMap.h
new file mode 100644
index 00000000..3e75f8f0
--- /dev/null
+++ b/k4MarlinWrapper/src/components/GlobalConvertedObjectsMap.h
@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2019-2023 Key4hep-Project.
+ *
+ * This file is part of Key4hep.
+ * See https://key4hep.github.io/key4hep-doc/ for further info.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef K4MARLINWRAPPER_CONVEREROBJECT_MAP_H
+#define K4MARLINWRAPPER_CONVEREROBJECT_MAP_H
+
+#include "k4EDM4hep2LcioConv/MappingUtils.h"
+
+#include <string_view>
+
+namespace EVENT {
+  class Track;
+  class TrackerHit;
+  class TrackerHitPlane;
+  class SimTrackerHit;
+  class CalorimeterHit;
+  class RawCalorimeterHit;
+  class SimCalorimeterHit;
+  class TPCHit;
+  class Cluster;
+  class Vertex;
+  class ReconstructedParticle;
+  class MCParticle;
+  class ParticleID;
+}  // namespace EVENT
+
+namespace edm4hep {
+  class Track;
+  class TrackerHit;
+  class TrackerHitPlane;
+  class SimTrackerHit;
+  class CalorimeterHit;
+  class RawCalorimeterHit;
+  class SimCalorimeterHit;
+  class RawTimeSeries;
+  class Cluster;
+  class Vertex;
+  class ReconstructedParticle;
+  class MCParticle;
+  class ParticleID;
+}  // namespace edm4hep
+
+namespace k4MarlinWrapper {
+
+  /**
+   * Fill all key value pairs from updates into map
+   */
+  template <typename Map, typename UpdateMap> void updateMap(Map& map, const UpdateMap& updates) {
+    for (const auto& [k, v] : updates) {
+      k4EDM4hep2LcioConv::detail::mapInsert(k, v, map);
+    }
+  }
+
+  namespace detail {
+    /// Detectors for checking whether T has a trackerHitPlanes and a particleIDs map
+    template <typename T> using has_trkhit_plane = decltype(std::declval<T>().trackerHitPlanes);
+    template <typename T> using has_particle_id  = decltype(std::declval<T>().particleIDs);
+  }  // namespace detail
+
+  /**
+   * The LCIO <-> EDM4hep object mapping that holds the relations between all
+   * converted objects from all converters that are running.
+   */
+  struct GlobalConvertedObjectsMap {
+    template <typename K, typename V> using ObjectMapT = k4EDM4hep2LcioConv::VecMapT<K, V>;
+
+    ObjectMapT<EVENT::Track*, edm4hep::Track>                                 tracks{};
+    ObjectMapT<EVENT::TrackerHit*, edm4hep::TrackerHit>                       trackerHits{};
+    ObjectMapT<EVENT::SimTrackerHit*, edm4hep::SimTrackerHit>                 simTrackerHits{};
+    ObjectMapT<EVENT::CalorimeterHit*, edm4hep::CalorimeterHit>               caloHits{};
+    ObjectMapT<EVENT::RawCalorimeterHit*, edm4hep::RawCalorimeterHit>         rawCaloHits{};
+    ObjectMapT<EVENT::SimCalorimeterHit*, edm4hep::SimCalorimeterHit>         simCaloHits{};
+    ObjectMapT<EVENT::TPCHit*, edm4hep::RawTimeSeries>                        tpcHits{};
+    ObjectMapT<EVENT::Cluster*, edm4hep::Cluster>                             clusters{};
+    ObjectMapT<EVENT::Vertex*, edm4hep::Vertex>                               vertices{};
+    ObjectMapT<EVENT::ReconstructedParticle*, edm4hep::ReconstructedParticle> recoParticles{};
+    ObjectMapT<EVENT::MCParticle*, edm4hep::MCParticle>                       mcParticles{};
+    ObjectMapT<EVENT::TrackerHitPlane*, edm4hep::TrackerHitPlane>             trackerHitPlanes{};
+    ObjectMapT<EVENT::ParticleID*, edm4hep::ParticleID>                       particleIDs{};
+
+    constexpr static auto TESpath = std::string_view{"/Event/EDMConvGlobalObjMap"};
+
+    /**
+     * Update the map with contents from one converter run
+     */
+    template <typename ObjectMap> void update(const ObjectMap& localMap) {
+      updateMap(tracks, localMap.tracks);
+      updateMap(trackerHits, localMap.trackerHits);
+      updateMap(simTrackerHits, localMap.simTrackerHits);
+      updateMap(caloHits, localMap.caloHits);
+      updateMap(rawCaloHits, localMap.rawCaloHits);
+      updateMap(simCaloHits, localMap.simCaloHits);
+      updateMap(tpcHits, localMap.tpcHits);
+      updateMap(clusters, localMap.clusters);
+      updateMap(vertices, localMap.vertices);
+      updateMap(recoParticles, localMap.recoParticles);
+      updateMap(mcParticles, localMap.mcParticles);
+
+      if constexpr (det::is_detected_v<detail::has_trkhit_plane, ObjectMap>) {
+        updateMap(trackerHitPlanes, localMap.trackerHitPlanes);
+      }
+      if constexpr (det::is_detected_v<detail::has_particle_id, ObjectMap>) {
+        updateMap(particleIDs, localMap.particleIDs);
+      }
+    }
+  };
+}  // namespace k4MarlinWrapper
+
+#endif
diff --git a/k4MarlinWrapper/src/components/Lcio2EDM4hep.cpp b/k4MarlinWrapper/src/components/Lcio2EDM4hep.cpp
index b7a8b390..6c892b8b 100644
--- a/k4MarlinWrapper/src/components/Lcio2EDM4hep.cpp
+++ b/k4MarlinWrapper/src/components/Lcio2EDM4hep.cpp
@@ -17,6 +17,7 @@
  * limitations under the License.
  */
 #include "k4MarlinWrapper/converters/Lcio2EDM4hep.h"
+#include "GlobalConvertedObjectsMap.h"
 
 #include <EVENT/LCCollection.h>
 #include <Exceptions.h>
@@ -39,8 +40,16 @@
 #include <k4FWCore/DataHandle.h>
 #include <k4FWCore/MetaDataHandle.h>
 
+#include "GaudiKernel/AnyDataWrapper.h"
+
+#include <memory>
+
 DECLARE_COMPONENT(Lcio2EDM4hepTool);
 
+using namespace k4MarlinWrapper;
+
+using GlobalMapWrapper = AnyDataWrapper<GlobalConvertedObjectsMap>;
+
 Lcio2EDM4hepTool::Lcio2EDM4hepTool(const std::string& type, const std::string& name, const IInterface* parent)
     : GaudiTool(type, name, parent), m_eds("EventDataSvc", "Lcio2EDM4hepTool") {
   declareInterface<IEDMConverter>(this);
@@ -111,6 +120,26 @@ void Lcio2EDM4hepTool::registerCollection(
   }
 }
 
+namespace {
+  template <typename K, typename V> using ObjMapT = k4EDM4hep2LcioConv::VecMapT<K, V>;
+
+  struct ObjectMappings {
+    ObjMapT<lcio::Track*, edm4hep::MutableTrack>                                 tracks{};
+    ObjMapT<lcio::TrackerHit*, edm4hep::MutableTrackerHit>                       trackerHits{};
+    ObjMapT<lcio::SimTrackerHit*, edm4hep::MutableSimTrackerHit>                 simTrackerHits{};
+    ObjMapT<lcio::CalorimeterHit*, edm4hep::MutableCalorimeterHit>               caloHits{};
+    ObjMapT<lcio::RawCalorimeterHit*, edm4hep::MutableRawCalorimeterHit>         rawCaloHits{};
+    ObjMapT<lcio::SimCalorimeterHit*, edm4hep::MutableSimCalorimeterHit>         simCaloHits{};
+    ObjMapT<lcio::TPCHit*, edm4hep::MutableRawTimeSeries>                        tpcHits{};
+    ObjMapT<lcio::Cluster*, edm4hep::MutableCluster>                             clusters{};
+    ObjMapT<lcio::Vertex*, edm4hep::MutableVertex>                               vertices{};
+    ObjMapT<lcio::ReconstructedParticle*, edm4hep::MutableReconstructedParticle> recoParticles{};
+    ObjMapT<lcio::MCParticle*, edm4hep::MutableMCParticle>                       mcParticles{};
+    ObjMapT<lcio::TrackerHitPlane*, edm4hep::MutableTrackerHitPlane>             trackerHitPlanes{};
+    ObjMapT<lcio::ParticleID*, edm4hep::MutableParticleID>                       particleIDs{};
+  };
+}  // namespace
+
 StatusCode Lcio2EDM4hepTool::convertCollections(lcio::LCEventImpl* the_event) {
   // Convert Event Header outside the collections loop
   if (!collectionExist("EventHeader")) {
@@ -128,7 +157,7 @@ StatusCode Lcio2EDM4hepTool::convertCollections(lcio::LCEventImpl* the_event) {
     }
   }
 
-  auto lcio2edm4hepMaps = LCIO2EDM4hepConv::LcioEdmTypeMapping{};
+  auto lcio2edm4hepMaps = ::ObjectMappings{};
 
   std::vector<std::pair<std::string, EVENT::LCCollection*>>               lcRelationColls{};
   std::vector<std::tuple<std::string, EVENT::LCCollection*, std::string>> subsetColls{};
@@ -142,7 +171,7 @@ StatusCode Lcio2EDM4hepTool::convertCollections(lcio::LCEventImpl* the_event) {
         continue;  // No need to convert again
       }
       const auto& lcio_coll_type_str = lcio_coll->getTypeName();
-      debug() << "LCIO type of the relation is " << lcio_coll_type_str << endmsg;
+      debug() << "LCIO type of the collection is " << lcio_coll_type_str << endmsg;
 
       // We deal with subset collections and LCRelations once we have all data
       // converted
@@ -168,14 +197,31 @@ StatusCode Lcio2EDM4hepTool::convertCollections(lcio::LCEventImpl* the_event) {
     }
   }
 
+  // We want one "global" map that is created the first time it is use in the
+  // event.
+  //
+  // Technically getOrCreate is a thing in GaudiTool but that doesn't seem to
+  // easily work with the AnyDataWrapper we want to use here. So doing the two
+  // step process here
+  if (!exist<GlobalMapWrapper>(GlobalConvertedObjectsMap::TESpath.data())) {
+    debug() << "Creating GlobalconvertedObjectsMap for this event since it is not already in the EventStore" << endmsg;
+    auto globalObjMapWrapper = std::make_unique<GlobalMapWrapper>(GlobalConvertedObjectsMap{});
+    put(std::move(globalObjMapWrapper), GlobalConvertedObjectsMap::TESpath.data());
+  }
+
+  auto  globalObjMapWrapper = get<GlobalMapWrapper>(GlobalConvertedObjectsMap::TESpath.data());
+  auto& globalObjMap        = globalObjMapWrapper->getData();
+
+  globalObjMap.update(lcio2edm4hepMaps);
+
   // Now we can resolve relations, subset collections and LCRelations
-  LCIO2EDM4hepConv::resolveRelations(lcio2edm4hepMaps);
+  LCIO2EDM4hepConv::resolveRelations(lcio2edm4hepMaps, globalObjMap);
 
   for (const auto& [name, coll, type] : subsetColls) {
-    registerCollection(name, LCIO2EDM4hepConv::fillSubset(coll, lcio2edm4hepMaps, type), coll);
+    registerCollection(name, LCIO2EDM4hepConv::fillSubset(coll, globalObjMap, type), coll);
   }
 
-  for (auto&& assocColl : LCIO2EDM4hepConv::createAssociations(lcio2edm4hepMaps, lcRelationColls)) {
+  for (auto&& assocColl : LCIO2EDM4hepConv::createAssociations(globalObjMap, lcRelationColls)) {
     registerCollection(std::move(assocColl));  // TODO: Potentially handle metadata here?
   }
 
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 17576afd..77569e4b 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -17,6 +17,24 @@ See the License for the specific language governing permissions and
 limitations under the License.
 ]]
 
+gaudi_add_module(GaudiTestAlgorithms
+  SOURCES
+    src/MCRecoLinkChecker.cc
+  LINK
+    Gaudi::GaudiAlgLib
+    Gaudi::GaudiKernel
+    k4FWCore::k4FWCore
+    EDM4HEP::edm4hep
+)
+
+
+# Compile the Marlin test processors into a shared library
+find_package(Marlin REQUIRED)
+
+add_library(MarlinTestProcessors SHARED src/PseudoRecoProcessor.cc src/TrivialMCTruthLinkerProcessor.cc)
+target_link_libraries(MarlinTestProcessors PUBLIC ${Marlin_LIBRARIES})
+target_include_directories(MarlinTestProcessors PUBLIC ${Marlin_INCLUDE_DIRS})
+
 # Add test scripts
 
 find_program(BASH_PROGRAM bash)
@@ -66,6 +84,10 @@ if (BASH_PROGRAM)
   # Test the GeoSvc and TrackingCellIDEncodingSvc
   add_test( clic_geo_test ${BASH_PROGRAM} ${CMAKE_CURRENT_SOURCE_DIR}/scripts/clicGeoTest.sh )
 
+  # Test for checking whether the converters can resolve relations accross
+  # multiple processors
+  add_test( global_converter_maps ${BASH_PROGRAM} ${CMAKE_CURRENT_SOURCE_DIR}/scripts/global_converter_maps.sh )
+
   set_tests_properties (
       simple_processors
       simple_processors2
@@ -77,8 +99,9 @@ if (BASH_PROGRAM)
       clicRec_lcio_mt
       clicRec_edm4hep_input
       clic_geo_test
+      global_converter_maps
     PROPERTIES
-      ENVIRONMENT "TEST_DIR=${CMAKE_CURRENT_SOURCE_DIR};LD_LIBRARY_PATH=${CMAKE_INSTALL_PREFIX}/lib:${CMAKE_INSTALL_PREFIX}/lib64:$ENV{LD_LIBRARY_PATH};PYTHONPATH=${CMAKE_INSTALL_PREFIX}/python:$ENV{PYTHONPATH};EXAMPLE_DIR=${PROJECT_SOURCE_DIR}/k4MarlinWrapper/examples"
+      ENVIRONMENT "TEST_DIR=${CMAKE_CURRENT_SOURCE_DIR};LD_LIBRARY_PATH=${CMAKE_INSTALL_PREFIX}/lib:${CMAKE_INSTALL_PREFIX}/lib64:$ENV{LD_LIBRARY_PATH};PYTHONPATH=${CMAKE_INSTALL_PREFIX}/python:$ENV{PYTHONPATH};EXAMPLE_DIR=${PROJECT_SOURCE_DIR}/k4MarlinWrapper/examples;MARLIN_DLL=$ENV{MARLIN_DLL}:${CMAKE_CURRENT_BINARY_DIR}/libMarlinTestProcessors.so"
       )
 
     set_tests_properties(
diff --git a/test/README.md b/test/README.md
new file mode 100644
index 00000000..0b6f6e1a
--- /dev/null
+++ b/test/README.md
@@ -0,0 +1,57 @@
+<!--
+Copyright (c) 2019-2023 Key4hep-Project.
+
+This file is part of Key4hep.
+See https://key4hep.github.io/key4hep-doc/ for further info.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+# k4MarlinWrapper tests
+
+The test cases for the k4MarlinWrapper are somewhat involved in some cases.
+Hence, we try to describe their intent and their high level layout a bit here.
+We will be refering to the test cases by name as they are defined in the
+[`CMakeLists.txt`](./CMakeLists.txt) file in here.
+
+## `global_converter_maps`
+
+The main purpose of this test is to make sure that the EDM conversions work as
+expected, even if the event is converted piece-by-piece. In order to make that
+work the individual converter tool instances have to share a mapping of all
+corresponding LCIO and EDM4hep objects that have been converted (in either
+direction). This map is referred to as the *global object map*.
+
+### Setup
+
+The test is using the
+[`global_converter_maps.sh`](./scripts/global_converter_maps.sh) script which
+effectively simply runs the
+[`test_global_converter_maps.py`](./gaudi_opts/test_global_converter_maps.py)
+options file after downloading some input data. This options file uses two
+wrapped MarlinProcessors and one GaudiAlgorithm plus some converters inbetween
+them:
+- `PodioInput` to read the *MCParticles* collection from the input file (in
+  EDM4hep format)
+- [`PseudoRecoProcessor`](./src/PseudoRecoProcessor.cc) creates a reco particle
+  for every MC particle in the input collection
+  - An EDM4hep to LCIO converter converts the input MC particles up front
+  - An LCIO to EDM4hep converter converts the output reco particles afterwards
+- [`TrivalMCTruthLinkerProcessor`](./src/TrivialMCTruthLinkerProcessor.cc)
+  creates trivial links from the MC particles to the reco particles.
+  - An LCIO to EDM4hep converter converts the output collction to EDM4hep
+- [`MCRecoLinkChecker`](./src/MCRecoLinkChecker.cc) is a Gaudi algorithm that
+  simply checks whether the MC-reco links are as expected.
+
+Without the global converter map, the second LCIO to EDM4hep converter that is
+run after the MC - reco linker will not produce valid MC - reco links, as it
+does not have any knowledge about the input MCs and recos.
diff --git a/test/gaudi_opts/test_global_converter_maps.py b/test/gaudi_opts/test_global_converter_maps.py
new file mode 100644
index 00000000..4d1758f5
--- /dev/null
+++ b/test/gaudi_opts/test_global_converter_maps.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) 2019-2023 Key4hep-Project.
+#
+# This file is part of Key4hep.
+# See https://key4hep.github.io/key4hep-doc/ for further info.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import os
+
+from Gaudi.Configuration import *
+
+from Configurables import (
+    PodioInput,
+    MarlinProcessorWrapper,
+    k4DataSvc,
+    Lcio2EDM4hepTool,
+    EDM4hep2LcioTool,
+    MCRecoLinkChecker,
+    ApplicationMgr,
+)
+
+evtsvc = k4DataSvc("EventDataSvc")
+evtsvc.input = os.path.join(
+    "$TEST_DIR/inputFiles/", "ttbar_podio230830_edm4hep_frame.root"
+)
+
+podioInput = PodioInput("InputReader")
+podioInput.collections = ["MCParticles"]
+podioInput.OutputLevel = INFO
+
+PseudoRecoProc = MarlinProcessorWrapper("PseudoReco")
+PseudoRecoProc.ProcessorType = "PseudoRecoProcessor"
+PseudoRecoProc.Parameters = {
+    "InputMCs": ["MCParticles"],
+    "OutputRecos": ["PseudoRecoParticles"],
+}
+
+inputConverter = EDM4hep2LcioTool("InputConverter")
+inputConverter.convertAll = False
+inputConverter.collNameMapping = {"MCParticles": "MCParticles"}
+inputConverter.OutputLevel = DEBUG
+
+PseudoRecoProc.EDM4hep2LcioTool = inputConverter
+
+pseudoRecConverter = Lcio2EDM4hepTool("PseudoRecoConverter")
+pseudoRecConverter.convertAll = False
+pseudoRecConverter.collNameMapping = {"PseudoRecoParticles": "PseudoRecoParticles"}
+pseudoRecConverter.OutputLevel = DEBUG
+
+PseudoRecoProc.Lcio2EDM4hepTool = pseudoRecConverter
+
+TrivialMCTruthLinkerProc = MarlinProcessorWrapper("TvivialMCTruthLinker")
+TrivialMCTruthLinkerProc.ProcessorType = "TrivialMCTruthLinkerProcessor"
+TrivialMCTruthLinkerProc.Parameters = {
+    "InputMCs": ["MCParticles"],
+    "InputRecos": ["PseudoRecoParticles"],
+    "OutputMCRecoLinks": ["TrivialMCRecoLinks"],
+}
+
+mcTruthConverter = Lcio2EDM4hepTool("TrivialMCTruthLinkerConverter")
+mcTruthConverter.convertAll = False
+mcTruthConverter.collNameMapping = {"TrivialMCRecoLinks": "TrivialMCRecoLinks"}
+mcTruthConverter.OutputLevel = DEBUG
+
+TrivialMCTruthLinkerProc.Lcio2EDM4hepTool = mcTruthConverter
+
+mcLinkChecker = MCRecoLinkChecker("MCRecoLinkChecker")
+mcLinkChecker.InputMCRecoLinks = "TrivialMCRecoLinks"
+mcLinkChecker.InputMCs = "MCParticles"
+mcLinkChecker.InputRecos = "PseudoRecoParticles"
+mcLinkChecker.OutputLevel = DEBUG
+
+algList = [
+    podioInput,
+    PseudoRecoProc,
+    TrivialMCTruthLinkerProc,
+    mcLinkChecker,
+]
+
+ApplicationMgr(
+    TopAlg=algList, EvtSel="NONE", EvtMax=3, ExtSvc=[evtsvc], OutputLevel=INFO
+)
diff --git a/test/scripts/global_converter_maps.sh b/test/scripts/global_converter_maps.sh
new file mode 100644
index 00000000..5f8045ab
--- /dev/null
+++ b/test/scripts/global_converter_maps.sh
@@ -0,0 +1,31 @@
+#!/usr/bin/env sh
+##
+## Copyright (c) 2019-2023 Key4hep-Project.
+##
+## This file is part of Key4hep.
+## See https://key4hep.github.io/key4hep-doc/ for further info.
+##
+## Licensed under the Apache License, Version 2.0 (the "License");
+## you may not use this file except in compliance with the License.
+## You may obtain a copy of the License at
+##
+##     http://www.apache.org/licenses/LICENSE-2.0
+##
+## Unless required by applicable law or agreed to in writing, software
+## distributed under the License is distributed on an "AS IS" BASIS,
+## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+## See the License for the specific language governing permissions and
+## limitations under the License.
+##
+
+set -eu
+
+if [ ! -d $TEST_DIR/inputFiles/ ]; then
+    mkdir $TEST_DIR/inputFiles
+fi
+
+if [ ! -f $TEST_DIR/inputFiles/ttbar_podio230830_edm4hep_frame.root ]; then
+  wget https://github.com/AIDASoft/DD4hep/raw/master/DDTest/inputFiles/ttbar_podio230830_edm4hep_frame.root -P $TEST_DIR/inputFiles/
+fi
+
+k4run $TEST_DIR/gaudi_opts/test_global_converter_maps.py
diff --git a/test/src/MCRecoLinkChecker.cc b/test/src/MCRecoLinkChecker.cc
new file mode 100644
index 00000000..7a2310e3
--- /dev/null
+++ b/test/src/MCRecoLinkChecker.cc
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2019-2023 Key4hep-Project.
+ *
+ * This file is part of Key4hep.
+ * See https://key4hep.github.io/key4hep-doc/ for further info.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "MCRecoLinkChecker.h"
+
+DECLARE_COMPONENT(MCRecoLinkChecker)
+
+MCRecoLinkChecker::MCRecoLinkChecker(const std::string& name, ISvcLocator* pSL) : GaudiAlgorithm(name, pSL) {
+  declareProperty("InputMCRecoLinks", m_relationCollHandle, "Name of the input MC Reco link collection");
+  declareProperty("InputMCs", m_mcCollHandle, "Name of the input MC collection");
+  declareProperty("InputRecos", m_recoCollHandle, "Name of the input Reco collection");
+}
+
+StatusCode MCRecoLinkChecker::execute() {
+  const auto relationColl = m_relationCollHandle.get();
+  const auto mcColl       = m_mcCollHandle.get();
+  const auto recoColl     = m_recoCollHandle.get();
+
+  if (relationColl->size() != mcColl->size()) {
+    error() << "The MCReco relation collection does not have the expected size (expected: " << relationColl->size()
+            << ", actual: " << mcColl->size() << ")" << endmsg;
+    return StatusCode::FAILURE;
+  }
+
+  for (size_t i = 0; i < mcColl->size(); ++i) {
+    const auto mc       = (*mcColl)[i];
+    const auto reco     = (*recoColl)[i];
+    const auto relation = (*relationColl)[i];
+
+    if (relation.getWeight() != i) {
+      error() << "Relation " << i << " dost not have the correct weight (expected: " << i
+              << ", actual: " << relation.getWeight() << ")" << endmsg;
+      return StatusCode::FAILURE;
+    }
+
+    if (!(relation.getSim() == mc)) {
+      auto relMC = relation.getSim();
+      error() << "Relation " << i
+              << " does not point to the correct MCParticle (expected: " << mc.getObjectID().collectionID << "|"
+              << mc.getObjectID().index << ", actual: " << relMC.getObjectID().collectionID << "|"
+              << relMC.getObjectID().index << ")" << endmsg;
+      return StatusCode::FAILURE;
+    }
+
+    if (!(relation.getRec() == reco)) {
+      auto relRec = relation.getRec();
+      error() << "Relation " << i
+              << " does not point to the correct RecoParticle (expected: " << reco.getObjectID().collectionID << "|"
+              << reco.getObjectID().index << ", actual: " << relRec.getObjectID().collectionID << "|"
+              << relRec.getObjectID().index << ")" << endmsg;
+      return StatusCode::FAILURE;
+    }
+  }
+
+  return StatusCode::SUCCESS;
+}
diff --git a/test/src/MCRecoLinkChecker.h b/test/src/MCRecoLinkChecker.h
new file mode 100644
index 00000000..b416f113
--- /dev/null
+++ b/test/src/MCRecoLinkChecker.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2019-2023 Key4hep-Project.
+ *
+ * This file is part of Key4hep.
+ * See https://key4hep.github.io/key4hep-doc/ for further info.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef K4MARLINWRAPPER_TEST_MCRECOLINKCHECKER_H
+#define K4MARLINWRAPPER_TEST_MCRECOLINKCHECKER_H
+
+#include "edm4hep/MCParticleCollection.h"
+#include "edm4hep/MCRecoParticleAssociationCollection.h"
+#include "edm4hep/ReconstructedParticleCollection.h"
+
+#include "k4FWCore/DataHandle.h"
+
+#include <GaudiAlg/GaudiAlgorithm.h>
+#include <GaudiKernel/ISvcLocator.h>
+
+#include <string>
+
+class MCRecoLinkChecker : public GaudiAlgorithm {
+public:
+  explicit MCRecoLinkChecker(const std::string& name, ISvcLocator* pSL);
+  StatusCode execute() final;
+
+private:
+  DataHandle<edm4hep::MCRecoParticleAssociationCollection> m_relationCollHandle{"MCRecoTruthLinks",
+                                                                                Gaudi::DataHandle::Reader, this};
+  DataHandle<edm4hep::MCParticleCollection>            m_mcCollHandle{"MCParticles", Gaudi::DataHandle::Reader, this};
+  DataHandle<edm4hep::ReconstructedParticleCollection> m_recoCollHandle{"RecoParticles", Gaudi::DataHandle::Reader,
+                                                                        this};
+};
+
+#endif  // K4MARLINWRAPPER_TEST_MCRECOLINKCHECKER_H
diff --git a/test/src/PseudoRecoProcessor.cc b/test/src/PseudoRecoProcessor.cc
new file mode 100644
index 00000000..f2a15349
--- /dev/null
+++ b/test/src/PseudoRecoProcessor.cc
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2019-2023 Key4hep-Project.
+ *
+ * This file is part of Key4hep.
+ * See https://key4hep.github.io/key4hep-doc/ for further info.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "PseudoRecoProcessor.h"
+
+#include "EVENT/MCParticle.h"
+#include "IMPL/LCCollectionVec.h"
+#include "IMPL/ReconstructedParticleImpl.h"
+#include "UTIL/LCIterator.h"
+
+PseudoRecoProcessor aPseudoRecoProcessor;
+
+PseudoRecoProcessor::PseudoRecoProcessor() : marlin::Processor("PseudoRecoProcessor") {
+  registerInputCollection(LCIO::MCPARTICLE, "InputMCs", "Name of the input MCParticle collection", m_mcCollName,
+                          std::string("MCParticles"));
+
+  registerOutputCollection(LCIO::RECONSTRUCTEDPARTICLE, "OutputRecos",
+                           "Name of the output ReconstructedParticle collection", m_recoCollName,
+                           std::string("PseudoRecoParticles"));
+}
+
+void PseudoRecoProcessor::processEvent(LCEvent* evt) {
+  auto  mcParticleIter = UTIL::LCIterator<EVENT::MCParticle>(evt, m_mcCollName);
+  auto* recoColl       = new IMPL::LCCollectionVec(LCIO::RECONSTRUCTEDPARTICLE);
+
+  while (auto* mcParticle = mcParticleIter.next()) {
+    auto recoParticle = new IMPL::ReconstructedParticleImpl();
+    recoParticle->setCharge(mcParticle->getCharge());
+    recoParticle->setMomentum(mcParticle->getMomentum());
+    recoParticle->setEnergy(mcParticle->getEnergy());
+    recoParticle->setType(mcParticle->getPDG());
+
+    recoColl->addElement(recoParticle);
+  }
+
+  evt->addCollection(recoColl, m_recoCollName);
+}
diff --git a/test/src/PseudoRecoProcessor.h b/test/src/PseudoRecoProcessor.h
new file mode 100644
index 00000000..6258dc8a
--- /dev/null
+++ b/test/src/PseudoRecoProcessor.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2019-2023 Key4hep-Project.
+ *
+ * This file is part of Key4hep.
+ * See https://key4hep.github.io/key4hep-doc/ for further info.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "marlin/Processor.h"
+
+#include <string>
+
+class PseudoRecoProcessor : public marlin::Processor {
+public:
+  PseudoRecoProcessor();
+
+  marlin::Processor* newProcessor() override { return new PseudoRecoProcessor; }
+
+  /** process the event - In this case simply create one ReconstructedParticle
+   * per input MCParticle (copying the kinematics over)
+   */
+  void processEvent(LCEvent* evt) override;
+
+private:
+  std::string m_mcCollName{};
+  std::string m_recoCollName{};
+};
diff --git a/test/src/TrivialMCTruthLinkerProcessor.cc b/test/src/TrivialMCTruthLinkerProcessor.cc
new file mode 100644
index 00000000..e036285a
--- /dev/null
+++ b/test/src/TrivialMCTruthLinkerProcessor.cc
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2019-2023 Key4hep-Project.
+ *
+ * This file is part of Key4hep.
+ * See https://key4hep.github.io/key4hep-doc/ for further info.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "TrivialMCTruthLinkerProcessor.h"
+
+#include "EVENT/MCParticle.h"
+#include "EVENT/ReconstructedParticle.h"
+#include "IMPL/LCCollectionVec.h"
+#include "IMPL/LCRelationImpl.h"
+
+TrivialMCTruthLinkerProcessor aTrivialMCTruthLinkerProcessor;
+
+TrivialMCTruthLinkerProcessor::TrivialMCTruthLinkerProcessor() : marlin::Processor("TrivialMCTruthLinkerProcessor") {
+  registerInputCollection(LCIO::MCPARTICLE, "InputMCs", "Name of the input MCParticle collection", m_mcCollName,
+                          std::string("MCParticles"));
+
+  registerInputCollection(LCIO::RECONSTRUCTEDPARTICLE, "InputRecos",
+                          "Name of the input ReconstructedParticle collection", m_recoCollName,
+                          std::string("PseudoRecoParticles"));
+  registerOutputCollection(LCIO::LCRELATION, "OutputMCRecoLinks", "Name of the output Reco - MC Truth link collection",
+                           m_relCollName, std::string("TrivialMCRecoLinks"));
+}
+
+void TrivialMCTruthLinkerProcessor::processEvent(LCEvent* evt) {
+  const auto mcColl   = evt->getCollection(m_mcCollName);
+  const auto recoColl = evt->getCollection(m_recoCollName);
+
+  // NOTE: Not using LCRelationNavigator here because the internal map might
+  // screw up the order and we want an easy check afterwards
+  auto relationColl = new IMPL::LCCollectionVec(LCIO::LCRELATION);
+  relationColl->parameters().setValue("FromType", LCIO::MCPARTICLE);
+  relationColl->parameters().setValue("ToType", LCIO::RECONSTRUCTEDPARTICLE);
+
+  for (int i = 0; i < mcColl->getNumberOfElements(); ++i) {
+    auto relation = new IMPL::LCRelationImpl();
+    relation->setFrom(mcColl->getElementAt(i));
+    relation->setTo(recoColl->getElementAt(i));
+    relation->setWeight(i);
+    relationColl->addElement(relation);
+  }
+
+  evt->addCollection(relationColl, m_relCollName);
+}
diff --git a/test/src/TrivialMCTruthLinkerProcessor.h b/test/src/TrivialMCTruthLinkerProcessor.h
new file mode 100644
index 00000000..5eaee996
--- /dev/null
+++ b/test/src/TrivialMCTruthLinkerProcessor.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2019-2023 Key4hep-Project.
+ *
+ * This file is part of Key4hep.
+ * See https://key4hep.github.io/key4hep-doc/ for further info.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "marlin/Processor.h"
+
+#include <string>
+
+class TrivialMCTruthLinkerProcessor : public marlin::Processor {
+public:
+  TrivialMCTruthLinkerProcessor();
+
+  marlin::Processor* newProcessor() override { return new TrivialMCTruthLinkerProcessor; }
+
+  /** process the event - In this case simply link MCparticle[i] with
+   * ReconstructedParticle[i]
+   */
+  void processEvent(LCEvent* evt) override;
+
+private:
+  std::string m_mcCollName{};
+  std::string m_recoCollName{};
+  std::string m_relCollName{};
+};