Add gdbserver support to ctest

Author: Pawel Karczewski

CONTRIBUTING.md

@@ -5,6 +5,7 @@
 - [Submitting Pull Requests](#submitting-pull-requests)
 - [Implementing persistent containers](#implementing-persistent-containers)
 - [Configuring GitHub fork](#configuring-github-fork)
+- [Debugging](#Debugging)
 
 # Opening New Issues
 
@@ -148,3 +149,17 @@ To enable automatic images pushing to GitHub Container Registry, following varia
   (with only read & write packages permissions), to be generated as described
   [here](https://docs.github.com/en/free-pro-team@latest/github/authenticating-to-github/creating-a-personal-access-token#creating-a-token)
   for selected account (user defined in above variable).
+
+# Debugging
+
+Test framework supports debugging under gdb.
+
+* For remote debugging set `GDBSERVER` environment variable. Its content will be passed to gdbserver
+application as first positional argument, so it should define how gdbserver will communicate with gdb.
+Example usage with a single test:
+
+```sh
+GDBSERVER=localhost:4444 ctest -R vector_comp_operators_0_none --output-on-failure
+```
+
+* For local debugging in graphical environment using cgdb, set `CGDB` environment variable to `gnome-terminal` or `konsole` accordingly to your setup.

tests/helpers.cmake

@@ -133,7 +133,12 @@ function(execute_common expect_success output_file name)
 
     set(cmd ${TRACE} ${name} ${ARGN})
 
-    if($ENV{CGDB})
+    if(DEFINED ENV{CGDB} AND DEFINED ENV{GDBSERVER})
+        message(FATAL_ERROR "CGDB and GDBSERVER shouldn't be used at the same time."
+                "You should choose one way of debugging and probably refill your coffee.")
+    endif()
+
+    if(DEFINED ENV{CGDB})
         find_program(KONSOLE NAMES konsole)
         find_program(GNOME_TERMINAL NAMES gnome-terminal)
         find_program(CGDB NAMES cgdb)
@@ -153,6 +158,18 @@ function(execute_common expect_success output_file name)
         endif()
     endif()
 
+    if(DEFINED ENV{GDBSERVER})
+        find_program(GDBSERVER NAMES gdbserver)
+        set(GDBSERVER_SETTINGS $ENV{GDBSERVER})
+        if (NOT GDBSERVER)
+            message(FATAL_ERROR "gdbserver not found.")
+        endif()
+        if(NOT (${TRACER} STREQUAL none))
+            message(FATAL_ERROR "Cannot use gdbserver with ${TRACER}")
+        endif()
+        set(cmd ${GDBSERVER} ${GDBSERVER_SETTINGS} ${cmd})
+    endif()
+
     if(${output_file} STREQUAL none)
         execute_process(COMMAND ${cmd}
             OUTPUT_QUIET