Do not remove backtrace files in cleanup test

Author: EZoni

Examples/CMakeLists.txt

@@ -198,7 +198,7 @@ function(add_warpx_test
     if(WarpX_TEST_CLEANUP)
         add_test(
             NAME ${name}.cleanup
-            COMMAND ${CMAKE_COMMAND} -E rm -rf ${THIS_WORKING_DIR}
+            COMMAND ${CMAKE_COMMAND} -P ${CMAKE_SOURCE_DIR}/Examples/test_cleanup.cmake ${THIS_WORKING_DIR}
         )
         # test cleanup depends on test run
         set_property(TEST ${name}.cleanup APPEND PROPERTY DEPENDS "${name}.run")

Examples/test_cleanup.cmake

@@ -0,0 +1,7 @@
+# delete all test files except backtrace
+file(GLOB test_files ${CMAKE_ARGV3}/*)
+foreach(file ${test_files})
+    if(NOT ${file} MATCHES "Backtrace*")
+        execute_process(COMMAND ${CMAKE_COMMAND} -E rm -r ${file})
+    endif()
+endforeach()