Add a `spawn_method` dynamic fixture

tests/conftest.py

@@ -28,3 +28,11 @@ def loglevel(request):
 @pytest.fixture(scope='session')
 def arb_addr():
     return _arb_addr
+
+
+def pytest_generate_tests(metafunc):
+    if 'spawn_method' in metafunc.fixturenames:
+        from multiprocessing import get_all_start_methods
+        methods = get_all_start_methods()
+        methods.remove('fork')
+        metafunc.parametrize("spawn_method", methods, scope='module')

tractor/testing/_tractor_test.py

@@ -24,7 +24,13 @@ def tractor_test(fn):
     injected to tests declaring these funcargs.
     """
     @wraps(fn)
-    def wrapper(*args, loglevel=None, arb_addr=None, **kwargs):
+    def wrapper(
+        *args,
+        loglevel=None,
+        arb_addr=None,
+        spawn_method='forkserver',
+        **kwargs
+    ):
         # __tracebackhide__ = True
         if 'arb_addr' in inspect.signature(fn).parameters:
             # injects test suite fixture value to test as well
@@ -34,9 +40,15 @@ def tractor_test(fn):
             # allows test suites to define a 'loglevel' fixture
             # that activates the internal logging
             kwargs['loglevel'] = loglevel
+        if 'spawn_method' in inspect.signature(fn).parameters:
+            # allows test suites to define a 'loglevel' fixture
+            # that activates the internal logging
+            kwargs['spawn_method'] = spawn_method
         return run(
             partial(fn, *args, **kwargs),
-            arbiter_addr=arb_addr, loglevel=loglevel
+            arbiter_addr=arb_addr,
+            loglevel=loglevel,
+            spawn_method=spawn_method,
         )
 
     return wrapper