fix sys.path for local workers Fixes #421

src/xdist/plugin.py

@@ -1,9 +1,12 @@
 import os
 import uuid
+import sys
 
 import py
 import pytest
 
+_sys_path = list(sys.path)  # freeze a copy of sys.path at interpreter startup
+
 
 def pytest_xdist_auto_num_workers():
     try:

src/xdist/remote.py

@@ -219,12 +219,14 @@ if __name__ == "__channelexec__":
     channel = channel  # noqa
     workerinput, args, option_dict, change_sys_path = channel.receive()
 
-    if change_sys_path:
+    if change_sys_path is None:
         importpath = os.getcwd()
         sys.path.insert(0, importpath)
         os.environ["PYTHONPATH"] = (
             importpath + os.pathsep + os.environ.get("PYTHONPATH", "")
         )
+    else:
+        sys.path = change_sys_path
 
     os.environ["PYTEST_XDIST_TESTRUNUID"] = workerinput["testrunuid"]
     os.environ["PYTEST_XDIST_WORKER"] = workerinput["workerid"]

src/xdist/workermanage.py

@@ -9,6 +9,7 @@ import pytest
 import execnet
 
 import xdist.remote
+from xdist.plugin import _sys_path
 
 
 def parse_spec_config(config):
@@ -261,7 +262,8 @@ class WorkerController:
         remote_module = self.config.hook.pytest_xdist_getremotemodule()
         self.channel = self.gateway.remote_exec(remote_module)
         # change sys.path only for remote workers
-        change_sys_path = not self.gateway.spec.popen
+        # restore sys.path from a frozen copy for local workers
+        change_sys_path = _sys_path if self.gateway.spec.popen else None
         self.channel.send((self.workerinput, args, option_dict, change_sys_path))
 
         if self.putevent:

testing/test_remote.py

@@ -234,7 +234,7 @@ def test_remote_env_vars(testdir):
 
 
 def test_remote_inner_argv(testdir):
-    """Test/document the behavior due to execnet using `python -c`."""
+    """Work around sys.path differences due to execnet using `python -c`."""
     testdir.makepyfile(
         """
         import sys
@@ -292,3 +292,17 @@ def test_remote_usage_prog(testdir, request):
     result = testdir.runpytest_subprocess("-n1")
     assert result.ret == 1
     result.stdout.fnmatch_lines(["*usage: *", "*error: my_usage_error"])
+
+
+def test_remote_sys_path(testdir):
+    """Test/document the behavior due to execnet using `python -c`."""
+    testdir.makepyfile(
+        """
+        import sys
+
+        def test_sys_path():
+            assert "" not in sys.path
+        """
+    )
+    result = testdir.runpytest("-n1")
+    assert result.ret == 0