add -g run_wml_tests option to run gdb backtrace in case of crash

And use it on travis

.travis.yml

@@ -28,6 +28,8 @@ install:
     - time sudo apt-get install -qq libboost-iostreams-dev libboost-program-options-dev libboost-regex-dev libboost-system-dev libboost-test-dev libcairo2-dev libfribidi-dev libpango1.0-dev libsdl-image1.2-dev libsdl-mixer1.2-dev libsdl-net1.2-dev libsdl-ttf2.0-dev
     - if [ "$CXX" = "g++" ]; then time sudo apt-get install g++-4.8; fi
     - if [ "$CXX" = "g++" ]; then export CXX="g++-4.8"; fi
+    - if [ "$WML_TESTS" = true]; then sudo apt-get install gdb; fi
+# gdb is used to generate a backtrace if a wml test crashes, this is -g option to run_wml_tests
     - if [ "$CHECK_UTF8" = true ]; then time sudo apt-get install -qq moreutils; fi
 script: 
     - if [ "$CHECK_UTF8" = true ]; then time ./utils/travis/check_utf8.sh; fi
@@ -37,7 +39,7 @@ script:
     - "export DISPLAY=:99.0"
     - "sh -e /etc/init.d/xvfb start"
     - time if [[ "$CPP_TESTS" = true ]]; then ./test; export TEST_ERROR_CODE=$?; ./utils/travis/exit_wrapper.sh $TEST_ERROR_CODE; fi
-    - if [[ "$WML_TESTS" = true ]]; then time ./run_wml_tests -v -t "$WML_TEST_TIME"; fi
+    - if [[ "$WML_TESTS" = true ]]; then time ./run_wml_tests -g -v -t "$WML_TEST_TIME"; fi
 after_failure:
     - if [ -f "errors.log" ]; then echo -e "\n*** \n*\n* Errors reported in wml unit tests, here is errors.log...\n*\n*** \n"; cat errors.log; fi
     - if [ "$TEST_ERROR_CODE" = 200 ]; then echo -e "\n***\n*\n* Encountered a segfault in the c++ unit test executable, attempting to get a backtrace in the remaining time...\n*\n***\n"; fi

run_wml_tests

@@ -16,6 +16,7 @@ usage()
   echo -e "\t-s\tDisable strict mode. By default, we run wesnoth with option"
   echo -e "\t  \t'--log-strict=warning' to ensure errors result in a failed test."
   echo -e "\t-d\tRun wesnoth-debug binary instead of wesnoth."
+  echo -e "\t-g\tIf we encounter a crash, generate a backtrace using gdb. Must have gdb installed for this option."
   echo -e "\t-p arg\tPath to wesnoth binary. By default assume it is with this script."
   echo -e "\t-l arg\tLoads list of tests from the given file."
   echo -e "\t  \tBy default, the file is wml_test_schedule."
@@ -164,11 +165,18 @@ run_test()
     echo "$command" "2> error.log"
   fi
   $command 2> error.log
-  if check_errs $2 $? $1; then 
+  error_code="$?"
+  if check_errs $2 $error_code $1; then
     FirstTest=0 #Only start using validcache flag when at least one test has passed without error
     handle_error_log 0
     return 0
   else
+    # If we got a code of value at least 128, and it wasn't KILL timeout, it means we segfaulted / failed assertion etc. most likely, so run gdb to get a backtrace
+    if [ "$GdbBacktraceMode" -eq 1 -a "$error_code" -ge 128 -a "$error_code" -ne 137 ]; then
+        echo -e "\n* Launching gdb for a backtrace...\n" >>error.log
+        gdb -q -batch -ex start -ex continue -ex bt -ex quit --args $binary $opts $extra_opts >>error.log
+    fi
+
     handle_error_log 1
     return 1
   fi
@@ -183,10 +191,11 @@ LoadFile="wml_test_schedule"
 BinPath="./"
 StrictMode=1
 DebugMode=0
+GdbBacktraceMode=0
 extra_opts=""
 basetimer=10
 
-while getopts ":hvwusdp:l:a:t:" Option
+while getopts ":hvwusdgp:l:a:t:" Option
 do
   case $Option in
     h )
@@ -212,6 +221,9 @@ do
     d )
       DebugMode=1
       ;;
+    g )
+      GdbBacktraceMode=1
+      ;;
     p )
       BinPath="$OPTARG"
       ;;