fix(test): Run tests only if pythia is available

ROOT has dropped pythia6 support with recent version. Execute the Pythia
related tests only if Pythia6 and/or Pythia8 is available.

Author: fuhlig1

examples/simulation/Tutorial1/macros/CMakeLists.txt

@@ -22,19 +22,23 @@ foreach(mcEngine IN LISTS mcEngine_list)
     PASS_REGULAR_EXPRESSION "Macro finished successfully"
   )
 
-  add_test(NAME ex_sim_tutorial1_pythia6_${mcEngine}
-           COMMAND ${CMAKE_CURRENT_BINARY_DIR}/run_tutorial1_pythia6.sh 10 \"${mcEngine}\")
-  set_tests_properties(ex_sim_tutorial1_pythia6_${mcEngine} PROPERTIES
-    TIMEOUT ${maxTestTime}
-    PASS_REGULAR_EXPRESSION "Macro finished successfully"
-  )
+  if(Pythia6_FOUND)
+    add_test(NAME ex_sim_tutorial1_pythia6_${mcEngine}
+             COMMAND ${CMAKE_CURRENT_BINARY_DIR}/run_tutorial1_pythia6.sh 10 \"${mcEngine}\")
+    set_tests_properties(ex_sim_tutorial1_pythia6_${mcEngine} PROPERTIES
+      TIMEOUT ${maxTestTime}
+      PASS_REGULAR_EXPRESSION "Macro finished successfully"
+    )
+  endif()
 
-  add_test(NAME ex_sim_tutorial1_pythia8_${mcEngine}
-           COMMAND ${CMAKE_CURRENT_BINARY_DIR}/run_tutorial1_pythia8.sh 10 \"${mcEngine}\")
-  set_tests_properties(ex_sim_tutorial1_pythia8_${mcEngine} PROPERTIES
-    TIMEOUT ${maxTestTime}
-    PASS_REGULAR_EXPRESSION "Macro finished successfully"
-  )
+  if(Pythia8_FOUND)
+    add_test(NAME ex_sim_tutorial1_pythia8_${mcEngine}
+             COMMAND ${CMAKE_CURRENT_BINARY_DIR}/run_tutorial1_pythia8.sh 10 \"${mcEngine}\")
+    set_tests_properties(ex_sim_tutorial1_pythia8_${mcEngine} PROPERTIES
+      TIMEOUT ${maxTestTime}
+      PASS_REGULAR_EXPRESSION "Macro finished successfully"
+    )
+  endif()
 
   add_test(NAME ex_sim_tutorial1_urqmd_${mcEngine}
            COMMAND ${CMAKE_CURRENT_BINARY_DIR}/run_tutorial1_urqmd.sh 2 \"${mcEngine}\")