Add a test for it

DaVinciExamples/tests/qmtest/debugging.qms/test_example-PrintDecayTree.qmt

+<?xml version="1.0" ?>
+<!--
+    (c) Copyright 2021 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.
+-->
+<!DOCTYPE extension  PUBLIC '-//QM/2.3/Extension//EN'  'http://www.codesourcery.com/qm/dtds/2.3/-//qm/2.3/extension//en.dtd'>
+<extension class="GaudiTest.GaudiExeTest" kind="test">
+<argument name="program"><text>gaudirun.py</text></argument>
+<argument name="timeout"><integer>3600</integer></argument>
+<argument name="args"><set>
+  <text>$DAVINCIEXAMPLESROOT/python/DaVinciExamples/debugging/example-PrintDecayTree.py</text>
+</set></argument>
+<argument name="validator"><text>
+findReferenceBlock("""
+PrintJpsis.PrintDecayTreeTool              INFO                 Name         E         M         P        Pt       phi        Vz    P(C/K)   PP(C/K)
+PrintJpsis.PrintDecayTreeTool              INFO                            MeV       MeV       MeV       MeV      mrad        mm
+PrintJpsis.PrintDecayTreeTool              INFO J/psi(1S)            64348.53   3151.00  64271.34   5490.37   -280.39    -51.66       0/0       N/A
+PrintJpsis.PrintDecayTreeTool              INFO +-->mu+               9627.27    105.66   9626.69    387.30   2023.68    -53.56       1/4       2/4
+PrintJpsis.PrintDecayTreeTool              INFO +-->mu-              54723.91    105.66  54723.81   5756.74   -330.64    -51.01      1/40      2/40
+PrintJpsis.PrintDecayTreeTool              INFO
+PrintJpsis.PrintDecayTreeTool              INFO Used TES locations :-
+PrintJpsis.PrintDecayTreeTool              INFO       1 = '/Event/FunctionalParticleMaker/Particles'
+PrintJpsis.PrintDecayTreeTool              INFO       2 = '/Event/Rec/ProtoP/Charged'
+PrintJpsis.PrintDecayTreeTool              INFO       0 = '/Event/StdLooseJpsi2MuMu/Particles'
+PrintJpsis.PrintDecayTreeTool              INFO
+""", stdout, result, causes, signature_offset = 0)
+countErrorLines({"FATAL":0, "ERROR":0})
+<argument name="exit_code"><integer>1</integer></argument>
+</text></argument>
+</extension>