Tests: don't create byte-code cache when calling Python from SVN

Creating `__pycache__` directories in SVN's lib/ directory can cause
updating SVN to fail. Add the -B flag when TEST_PYTHON_EXE from LIBDIR
is used so so Python doesn't generate this cache.

CMakeLists.txt

@@ -550,6 +550,7 @@ endif()
 option(WITH_GTESTS "Enable GTest unit testing" OFF)
 option(WITH_OPENGL_RENDER_TESTS "Enable OpenGL render related unit testing (Experimental)" OFF)
 option(WITH_OPENGL_DRAW_TESTS "Enable OpenGL UI drawing related unit testing (Experimental)" OFF)
+# NOTE: All callers of this must add `TEST_PYTHON_EXE_EXTRA_ARGS` before any other arguments.
 set(TEST_PYTHON_EXE "" CACHE PATH "Python executable to run unit tests")
 mark_as_advanced(TEST_PYTHON_EXE)
 

tests/CMakeLists.txt

@@ -31,6 +31,19 @@ elseif(NOT EXISTS ${TEST_PYTHON_EXE})
 endif()
 
 
+# Include these arguments before all others, they must not interfere with Python execution.
+set(TEST_PYTHON_EXE_EXTRA_ARGS)
+
+# Check if this a Blender managed Python installation, if so, don't add `*.pyc` files.
+if(LIBDIR)
+  cmake_path(IS_PREFIX LIBDIR "${TEST_PYTHON_EXE}" NORMALIZE _is_prefix)
+  if(_is_prefix)
+    # Keep the Python in Blender's SVN LIBDIR pristine, to avoid conflicts on updating.
+    set(TEST_PYTHON_EXE_EXTRA_ARGS "-B")
+  endif()
+  unset(_is_prefix)
+endif()
+
 # For testing with Valgrind
 # set(TEST_BLENDER_EXE valgrind --track-origins=yes --error-limit=no ${TEST_BLENDER_EXE})
 

tests/blender_as_python_module/CMakeLists.txt

@@ -8,7 +8,7 @@ function(add_blender_as_python_module_test testname testscript)
 
   add_test(
     NAME ${testname}
-    COMMAND ${TEST_PYTHON_EXE} ${testscript} ${ARGN}
+    COMMAND ${TEST_PYTHON_EXE} ${TEST_PYTHON_EXE_EXTRA_ARGS} ${testscript} ${ARGN}
   )
 
   # On macOS, asan library must be loaded early.

tests/python/CMakeLists.txt

@@ -41,7 +41,7 @@ function(add_python_test testname testscript)
 
   add_test(
     NAME ${testname}
-    COMMAND ${TEST_PYTHON_EXE} ${testscript} ${ARGN}
+    COMMAND ${TEST_PYTHON_EXE} ${TEST_PYTHON_EXE_EXTRA_ARGS} ${testscript} ${ARGN}
   )
   set_tests_properties(${testname} PROPERTIES ENVIRONMENT
     LSAN_OPTIONS=exitcode=0:$ENV{LSAN_OPTIONS}