force multiprocessing default start method to "fork" for tests

cosmo/clients/__init__.py

@@ -0,0 +1,10 @@
+import multiprocessing
+
+
+def get_client_mp_context(method=None):
+    # this will set and return the global context, by default
+    # since method is None. the reason why we use this
+    # boilerplate is to have an anchor point for
+    # monkeypatching the multiprocessing context
+    # during tests.
+    return multiprocessing.get_context(method=method)

cosmo/clients/netbox_v4.py

@@ -4,6 +4,7 @@
 from multiprocessing import Manager
 from string import Template
 
+from cosmo.clients import get_client_mp_context
 from cosmo.clients.netbox_client import NetboxAPIClient
 
 
@@ -658,7 +659,7 @@ def get_data(self, device_config):
         # from the main thread. by default this is not possible, see
         # https://stackoverflow.com/questions/72411392/can-you-do-nested-parallelization-using-multiprocessing-in-python
         # this avoids having to re-architecture completely using worker/task/queue model.
-        with Manager() as manager:
+        with get_client_mp_context().Manager() as manager:
             client = NetboxAPIClient(self.url, self.token, manager.dict())
 
             for d in device_list:

cosmo/tests/test_netboxclient.py

@@ -1,14 +1,21 @@
+from unittest.mock import patch
+
 import pytest
 from packaging.version import Version
 
 import cosmo.tests.utils as utils
 from cosmo.clients.netbox import NetboxClient
+from cosmo.tests.utils import override_get_client_mp_context
 
 TEST_URL = "https://netbox.example.com"
 TEST_TOKEN = "token123"
 TEST_DEVICE_CFG = {"router": ["router1", "router2"], "switch": ["switch1", "switch2"]}
 
 
+@patch(
+    "cosmo.clients.netbox_v4.get_client_mp_context",
+    new=override_get_client_mp_context("fork"),
+)
 def test_case_get_data(mocker):
     mockAnswer = {
         "device_list": [],

cosmo/tests/utils.py

@@ -1,4 +1,12 @@
 import json
+import multiprocessing
+
+
+def override_get_client_mp_context(method=None):
+    def overriden_get_client_mp_context():
+        return multiprocessing.get_context(method=method)
+
+    return overriden_get_client_mp_context
 
 
 class CommonSetup:
@@ -17,6 +25,15 @@ def __init__(
         self.patches.append(self.mocker.patch.dict("os.environ", environ))
         # patch args, since current ones are from pytest call
         self.patches.append(self.mocker.patch("sys.argv", args))
+        # patch netbox client default mp context for the time of the tests
+        # patch may be ineffective since not in correct namespace(?)
+        self.patches.append(
+            self.mocker.patch(
+                "cosmo.clients.netbox_v4.get_client_mp_context",
+                new=override_get_client_mp_context("fork"),
+            )
+        )
+
         # patch configuration file lookup if requested
 
         # Note: If there is no configuration file given, we still need to patch this.

package.nix

@@ -1,6 +1,4 @@
-{ lib,
-  stdenv,
-  buildPythonApplication,
+{ buildPythonApplication,
   python,
   poetry-core,
   requests,
@@ -41,16 +39,6 @@ buildPythonApplication rec {
     coverage
   ];
 
-  disabledTests = lib.optionals stdenv.hostPlatform.isDarwin [
-    # https://github.com/wobcom/cosmo/issues/85
-    "test_limit_argument_with_commas"
-    "test_limit_arguments_with_repeat"
-    "test_device_generation_ansible"
-    "test_device_generation_nix"
-    "test_device_processing_error"
-    "test_case_get_data"
-  ];
-
   passthru = {
     pythonEnv = python.withPackages (_: dependencies);
   };