BUG: ExtensionBuildSystem: Fix issue preventing build of dependent extensions

To prevent extension test displaying string "ERROR:" from being considered
as build failure and causing the overall build of all extensions to fail,
this commit updates the execution of the build wrapper script to ensure
its standard output and error streams are logged to file.

Note that this was only observed when using Visual Studio generator on
Windows because in that case, there are no CTest launcher.
See https://cmake.org/cmake/help/latest/module/CTestUseLaunchers.html

This commit also improves the extension build system tests to avoid future
regressions.

It is a follow up of r26223 (BUG: Extension build system: Sandbox download
step and report download error)

Fix https://issues.slicer.org/view.php?id=4247

git-svn-id: http://svn.slicer.org/Slicer4/trunk@27944 3bd1e089-480b-0410-8dfb-8563597acbee

Author: jcfr

Extensions/CMake/SlicerBlockBuildPackageAndUploadExtensions.cmake

@@ -233,14 +233,20 @@ foreach(EXTENSION_NAME ${EXTENSION_LIST})
   #
   set(build_extension_wrapper_script
     ${CMAKE_CURRENT_BINARY_DIR}/build_${proj}_wrapper_script.cmake)
+  set(build_output_file "${CMAKE_CURRENT_BINARY_DIR}/build_${proj}output.txt")
+  set(build_error_file "${CMAKE_CURRENT_BINARY_DIR}/build_${proj}_error.txt")
   #message(STATUS "Configuring extension upload wrapper script: ${build_extension_wrapper_script}")
   file(WRITE ${build_extension_wrapper_script} "
     execute_process(
       COMMAND ${wrapper_command}
       WORKING_DIR \"${EXTENSION_SUPERBUILD_BINARY_DIR}\"
+      OUTPUT_FILE \"${build_output_file}\"
+      ERROR_FILE \"${build_error_file}\"
       RESULT_VARIABLE result
       )
     message(STATUS \"build_${proj}_wrapper_script: Ignoring result \${result}\")
+    message(STATUS \"build_${proj}_output_file: ${build_output_file}\")
+    message(STATUS \"build_${proj}_error_file: ${build_error_file}\")
     ")
 
   # Add extension external project

Extensions/CMake/Testing/SlicerExtensionBuildSystemTest.py

@@ -286,8 +286,18 @@ def _prepare_test_binary_dir(self, test_binary_dir):
         # dependers of ExtensionsA can still configure/build/test without
         # any issues. See #4247
         module_dir = extension_dir + '/Mod%s' % suffix
-        with open(module_dir + '/Testing/Python/CMakeLists.txt', 'a') as content:
-          content.write("add_test(NAME FailingTest COMMAND invalid_test)")
+        module_cmakelists = module_dir + '/Testing/Python/CMakeLists.txt'
+        with open(module_cmakelists, 'a') as content:
+          content.write("add_test(NAME FailingTest COMMAND invalid_test)\n")
+
+        display_error_script = module_dir + '/Testing/Python/slicerDisplayErrors.cmake'
+        with open(display_error_script, 'w') as content:
+          content.write(textwrap.dedent("""
+          message("ERROR: In /path/to/Slicer/qSlicerCoreApplication.cxx, line 212
+          vtkObject (0x25f2b30): This is an an error message from VTK")
+          """))
+        with open(module_cmakelists, 'a') as content:
+          content.write("add_test(NAME TestDisplayingError COMMAND ${CMAKE_COMMAND} -P \"%s\")\n" % display_error_script)
 
       if suffix == 'B':
         project = ExtensionProject(extension_dir)