create tmpdir in master xdist worker and store lockfiles there

.github/scripts/unit_test_runner.sh

@@ -2,11 +2,11 @@
 
 # used to pass --cov=$path and --cov-append to pytest
 if [ "$1" != "" ]; then
-    pytest "$1" tests/unit/
+    pytest "$1" tests/unit/ -n auto
     status_code=$?
     python -m coverage report
 else
-    pytest tests/unit/
+    pytest tests/unit/ -n auto
     status_code=$?
 fi
 

tests/conftest.py

@@ -1,17 +1,54 @@
 # pylint: disable=redefined-outer-name
+import os
 from pathlib import Path
+import tempfile
+import shutil
 from contextlib import contextmanager
-from tempfile import NamedTemporaryFile
 import pytest
 from filelock import FileLock
 from solc_select import solc_select
 from slither import Slither
 
 
-@pytest.fixture()
-def solc_binary_path():
+def pytest_configure(config):
+    """Create a temporary directory for the tests to use."""
+    if is_master():
+        config.stash["shared_directory"] = tempfile.mkdtemp()
+
+
+def pytest_unconfigure(config):
+    """Remove the temporary directory after the tests are done."""
+    if is_master():
+        shutil.rmtree(config.stash["shared_directory"])
+
+
+def pytest_configure_node(node):
+    """Configure each worker node with the shared directory."""
+    node.workerinput["shared_directory"] = node.config.stash["shared_directory"]
+
+
+def is_master():
+    """Returns True if the current process is the master process (which does not have a worker id)."""
+    return os.environ.get("PYTEST_XDIST_WORKER") is None
+
+
+@pytest.fixture
+def shared_directory(request):
+    """Returns the shared directory for the current process."""
+    if is_master():
+        return request.config.stash["shared_directory"]
+    return request.config.workerinput["shared_directory"]
+
+
+@pytest.fixture
+def solc_binary_path(shared_directory):
+    """
+    Returns the path to the solc binary for the given version.
+    If the binary is not installed, it will be installed.
+    """
+
     def inner(version):
-        lock = FileLock(f"{version}.lock", timeout=60)
+        lock = FileLock(f"{shared_directory}/{version}.lock", timeout=60)
         with lock:
             if not solc_select.artifact_path(version).exists():
                 print("Installing solc version", version)
@@ -21,18 +58,17 @@ def solc_binary_path():
     return inner
 
 
-@pytest.fixture()
+@pytest.fixture
 def slither_from_source(solc_binary_path):
     @contextmanager
     def inner(source_code: str, solc_version: str = "0.8.19"):
-        """Yields a Slither instance using source_code string and solc_version
-
-        Creates a temporary file and changes the solc-version temporary to solc_version.
+        """Yields a Slither instance using source_code string and solc_version.
+        Creates a temporary file and compiles with solc_version.
         """
 
         fname = ""
         try:
-            with NamedTemporaryFile(mode="w", suffix=".sol", delete=False) as f:
+            with tempfile.NamedTemporaryFile(mode="w", suffix=".sol", delete=False) as f:
                 fname = f.name
                 f.write(source_code)
             solc_path = solc_binary_path(solc_version)