Rework utopya test invocation to support process spawning

The pytest framework seems to have its troubles with multiprocessing.
Prior to this commit, running `test_task.py` individually would succeed,
while running the whole test suite would fail, just as one example.

This commit addresses those issues by wrapping `pytest.main` execution
into the `if __name__ == '__main__'` guard and ensuring that the utopya
module is in the system path (regardless of how pytest may have modified
it). See pytest-dev/pytest#958 for more info.

run_test.py

@@ -0,0 +1,23 @@
+#!/usr/bin/python3
+"""This is a custom entrypoint to pytest which takes care that pytest is
+run within the ``if __name__ == '__main__'`` guard, thereby resolving issues
+with the multiprocessing module.
+
+We are not the only ones with this problem, see:
+    - https://github.com/pytest-dev/pytest/issues/958
+    - https://github.com/web-platform-tests/wpt/issues/24880
+"""
+
+import os
+import sys
+
+import pytest
+
+# Ensure that utopya is in the path and already imported at this point. If not
+# doing this, discovery of the utopya module may fail if the test modules are
+# imported when *spawning* a new multiprocessing.Process ...
+sys.path.insert(0, os.path.dirname(__file__))
+import utopya
+
+if __name__ == '__main__':
+    sys.exit(pytest.main([__file__] + sys.argv[1:]))

setup.py

@@ -11,12 +11,12 @@
     'ruamel.yaml>=0.16.5',
 
     'paramspace>=2.5.4',
-    'dantro>=0.15.0a2',
+    'dantro>=0.15.2',
     # NOTE Version need also be set in python/CMakeLists.txt
 
     # Required for testing:
-    'pytest>=3.4.0',
-    'pytest-cov>=2.5.1',
+    'pytest>=6.2.1',
+    'pytest-cov>=2.10.1',
     'psutil>=5.6.7'
 ]
 
@@ -70,7 +70,6 @@ def read(*parts):
     packages=find_packages(exclude=["*.test", "*.test.*", "test.*", "test"]),
     package_data=dict(utopya=["cfg/*.yml"]),
     install_requires=INSTALL_DEPS,
-    test_suite='py.test',
     #
     # Command line scripts, installed into the virtual environment
     scripts=['bin/utopia']

test/cfg/batch_file.yml

@@ -61,5 +61,5 @@ tasks:
       # All other arguments are passed to `Model.create_frozen_mv`
 
     task2:
-      model_name: Allhoff2015
+      model_name: dummy
       run_dir: ~

test/test_task.py

@@ -7,9 +7,13 @@
 from time import sleep
 from functools import partial
 
+import multiprocessing
+# NOTE Need this import, otherwise tests that use multiprocessing hang forever
+
 import numpy as np
 import pytest
 
+import utopya
 from utopya.task import (Task, WorkerTask, TaskList,
                          PopenMPProcess, MPProcessTask,
                          enqueue_lines, parse_yaml_dict, SIGMAP)