Add a test for issue 100 in DaVinciTests

Closes #100 (closed).

The test is a shorter version of the original script focusing only on what was giving trouble.

DaVinciTests/python/DaVinciTests/mc/option_davinci-issue-100_multiple_bkgcat_mc-truth.py

+###############################################################################
+# (c) Copyright 2023 CERN for the benefit of the LHCb Collaboration           #
+#                                                                             #
+# This software is distributed under the terms of the GNU General Public      #
+# Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING".   #
+#                                                                             #
+# In applying this licence, 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.                                       #
+###############################################################################
+"""
+rst_title: Test for DaVinci issue 100
+rst_description: Test for DaVinci issue 100 on an incorrect behaviour
+of the `MCTruthAndBkgCat` helper in Analysis's `Phys/DaVinciMCTools` package,
+traced back to a bug in one of the tools internally called.
+The test ensures that several instances of `MCTruthAndBkgCat`
+can be used in the same script to produce several ntuples.
+rst_running: lbexec DaVinciTests.mc.option_davinci-issue-100_multiple_bkgcat_mc-truth:alg_config "$DAVINCITESTSROOT/python/DaVinciTests/mc/option_davinci-issue-100_multiple_bkgcat_mc-truth.yaml"
+rst_yaml: ../DaVinciTests/python/DaVinciTests/mc/option_davinci-issue-100_multiple_bkgcat_mc-truth.yaml
+"""
+from PyConf.reading import get_particles
+import Functors as F
+from FunTuple import FunctorCollection, FunTuple_Particles as Funtuple
+from FunTuple.functorcollections import SelectionInfo
+from DaVinciMCTools import MCTruthAndBkgCat
+from DaVinci.algorithms import add_filter
+from DaVinci import Options, make_config
+
+jpsi_branches = {
+    "J_psi_1S": "J/psi(1S) -> mu- mu+",
+    "muminus": "J/psi(1S) -> ^mu- mu+",
+    "muplus": "J/psi(1S) -> mu- ^mu+",
+}
+
+hlt2_tag_lines = [
+    "Hlt2TrackEff_DiMuon_VeloMuon_mup_Tag",
+    "Hlt2TrackEff_DiMuon_VeloMuon_mum_Tag",
+    "Hlt2TrackEff_DiMuon_SeedMuon_mup_Tag",
+    "Hlt2TrackEff_DiMuon_SeedMuon_mum_Tag",
+]
+
+hlt2_match_lines = [
+    "Hlt2TrackEff_DiMuon_VeloMuon_mup_Match",
+    "Hlt2TrackEff_DiMuon_VeloMuon_mum_Match",
+    "Hlt2TrackEff_DiMuon_SeedMuon_mup_Match",
+    "Hlt2TrackEff_DiMuon_SeedMuon_mum_Match",
+]
+
+
+def alg_config(options: Options):
+    evt_variables = SelectionInfo(
+        selection_type="Hlt2", trigger_lines=hlt2_tag_lines + hlt2_match_lines)
+
+    Tuples = {}
+    for line in hlt2_tag_lines:
+        jpsi_data = get_particles(f"/Event/HLT2/{line}/Particles")
+        MC_TRUTH = MCTruthAndBkgCat(
+            jpsi_data, name=f"MCTruthAndBkgCat_{line[-16:]}")
+        MCMOTHER_ID = lambda n: F.VALUE_OR(0) @ MC_TRUTH(F.MC_MOTHER(n, F.PARTICLE_ID))
+        MCMOTHER_KEY = lambda n: F.VALUE_OR(-1) @ MC_TRUTH(F.MC_MOTHER(n, F.OBJECT_KEY))
+
+        trueid_bkgcat_info = FunctorCollection({
+            "TRUEID":
+            F.VALUE_OR(0) @ MC_TRUTH(F.PARTICLE_ID),
+            "TRUEKEY":
+            F.VALUE_OR(-1) @ MC_TRUTH(F.OBJECT_KEY),
+            "TRUEPT":
+            MC_TRUTH(F.PT),
+            "TRUEM":
+            MC_TRUTH(F.MASS),
+            "MC_MOTHER_ID":
+            MCMOTHER_ID(1),
+            "MC_MOTHER_KEY":
+            MCMOTHER_KEY(1),
+            "MC_GD_MOTHER_ID":
+            MCMOTHER_ID(2),
+            "MC_GD_MOTHER_KEY":
+            MCMOTHER_KEY(2),
+            "MC_GD_GD_MOTHER_ID":
+            MCMOTHER_ID(3),
+            "MC_GD_GD_MOTHER_KEY":
+            MCMOTHER_KEY(3),
+            "BKGCAT":
+            MC_TRUTH.BkgCat,
+        })
+
+        variables = {"ALL": trueid_bkgcat_info}
+
+        jpsi_tuple = Funtuple(
+            name="Tuple_" + line,
+            tuple_name="DecayTree",
+            fields=jpsi_branches,
+            variables=variables,
+            event_variables=evt_variables,
+            inputs=jpsi_data,
+        )
+
+        decision = line + "Decision"
+        jpsi_filter = add_filter(f"Filter_{line}", f"HLT_PASS('{decision}')")
+
+        Tuples[line] = [jpsi_filter, jpsi_tuple]
+
+    return make_config(options, Tuples)