Use temporary copy of cirq-core instead of filelock

Do not block parallel builds.

Author: pavoljuhas

dev_tools/packaging/isolated_packages_test.py

@@ -17,9 +17,7 @@
 import subprocess
 from unittest import mock
 
-import filelock
 import pytest
-import xdist
 
 from dev_tools import shell_tools
 from dev_tools.modules import list_modules
@@ -34,24 +32,25 @@
 # the "isolation" fails and for example cirq-core would be on the PATH
 @mock.patch.dict(os.environ, {"PYTHONPATH": ""})
 @pytest.mark.parametrize('module', list_modules(), ids=[m.name for m in list_modules()])
-def test_isolated_packages(cloned_env, module, tmp_path_factory, request):
+def test_isolated_packages(cloned_env, module, tmp_path):
     env = cloned_env("isolated_packages", *PACKAGES)
 
     if str(module.root) != "cirq-core":
         assert f'cirq-core=={module.version}' in module.install_requires
 
-    # use filelock to ensure only one pip install process runs at a time,
-    # otherwise they conflict when building a local cirq-core wheel
-    lock_dir = tmp_path_factory.getbasetemp()
-    if xdist.is_xdist_worker(request):
-        lock_dir = lock_dir.parent
-    lock = filelock.FileLock(lock_dir / "test_isolated_packages-pip.lock")
-    with lock.acquire(timeout=30):
-        result = shell_tools.run(
-            f"{env}/bin/pip install ./{module.root} ./cirq-core".split(),
-            stderr=subprocess.PIPE,
-            check=False,
-        )
+    # TODO: Remove after upgrading package builds from setup.py to PEP-517
+    # Create per-process copy of cirq-core sources so that parallel builds
+    # of cirq-core wheel do not conflict.
+    tmp_cirq_core = (
+        [str(shutil.copytree("./cirq-core", tmp_path / "cirq-core"))]
+        if str(module.root) != "cirq-core"
+        else []
+    )
+    result = shell_tools.run(
+        [f"{env}/bin/pip", "install", f"./{module.root}", *tmp_cirq_core],
+        stderr=subprocess.PIPE,
+        check=False,
+    )
     assert result.returncode == 0, f"Failed to install {module.name}:\n{result.stderr}"
 
     result = shell_tools.run(