Fix #145594: Tests: Check Windows command line length for batched tests

This PR adds a check that batched tests do not surpass the Windows
command line limit of 32,767 characters (including the terminating null
character). This could previously happen if long path names were used.

Pull Request: https://projects.blender.org/blender/blender/pulls/145792

tests/python/modules/render_report.py

@@ -9,6 +9,7 @@ a HTML report showing the differences, for regression testing.
 
 import glob
 import os
+import sys
 import pathlib
 import shutil
 import subprocess
@@ -502,30 +503,46 @@ class Report:
 
         remaining_filepaths = filepaths[:]
         test_results = []
+        arguments_suffix = self._get_arguments_suffix()
 
         while len(remaining_filepaths) > 0:
             command = [blender]
             running_tests = []
 
+            # On Windows, there is a maximum length of 32,767 characters (including the terminating null character)
+            # for process command line commands, see:
+            # https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessa
+            command_line_length = len(blender)
+            for suffix in arguments_suffix:
+                # Add 3 for taking into account spaces and quotation marks potentially added by Python.
+                command_line_length += len(suffix) + 3
+
             # Construct output filepaths and command to run
             for filepath in remaining_filepaths:
-                running_tests.append(filepath)
-
                 testname = test_get_name(filepath)
-                print_message(testname, 'SUCCESS', 'RUN')
 
                 base_output_filepath = os.path.join(self.output_dir, "tmp_" + testname)
+                command_filepath = self._get_render_arguments(arguments_cb, filepath, base_output_filepath)
+
+                # Check if we have surpassed the command line limit.
+                for cmd in command_filepath:
+                    command_line_length += len(cmd) + 3
+                if sys.platform == 'win32' and command_line_length > 32766 and len(running_tests) > 0:
+                    break
+
+                print_message(testname, 'SUCCESS', 'RUN')
+                running_tests.append(filepath)
+                command.extend(command_filepath)
+
                 output_filepath = base_output_filepath + '0001.png'
                 if os.path.exists(output_filepath):
                     os.remove(output_filepath)
 
-                command.extend(self._get_render_arguments(arguments_cb, filepath, base_output_filepath))
-
                 # Only chain multiple commands for batch
                 if not batch:
                     break
 
-            command.extend(self._get_arguments_suffix())
+            command.extend(arguments_suffix)
 
             # Run process
             crash = False