Add global session uuid (fixes #524)

README.rst

@@ -276,6 +276,41 @@ defined:
 The information about the worker_id in a test is stored in the ``TestReport`` as
 well, under the ``worker_id`` attribute.
 
+
+Uniquely identifying the current test run
+-----------------------------------------
+
+*New in version 1.32.*
+
+If you need to globally distinguish one test run from others in your
+workers, you can use the ``testrun_uid`` fixture. For instance, let's say you
+wanted to create a separate database for each test run:
+
+.. code-block:: python
+
+    import pytest
+    from posix_ipc import Semaphore, O_CREAT
+
+    @pytest.fixture(scope="session", autouse=True)
+    def create_unique_database(testrun_uid):
+        """ create a unique database for this particular test run """
+        database_url = f"psql://myapp-{testrun_uid}"
+
+        with Semaphore(f"/{testrun_uid}-lock", flags=O_CREAT, initial_value=1):
+            if not database_exists(database_url):
+                create_database(database_url)
+
+    @pytest.fixture()
+    def db(testrun_uid):
+        """ retrieve unique database """
+        database_url = f"psql://myapp-{testrun_uid}"
+        return database_get_instance(database_url)
+
+
+Additionally, during a test run, the following environment variable is defined:
+
+* ``PYTEST_XDIST_TESTRUNUID`: the unique id of the test run
+
 Acessing ``sys.argv`` from the master node in workers
 -----------------------------------------------------
 

changelog/524.feature

@@ -0,0 +1,2 @@
+Add `testrun_uid` fixture. This is a shared value that uniquely identifies a test run among all workers.
+This also adds a `PYTEST_XDIST_TESTRUNUID` environment variable that is accessible within a test as well as a command line option `--testrunuid` to manually set the value from outside.

src/xdist/plugin.py

@@ -1,4 +1,5 @@
 import os
+import uuid
 
 import py
 import pytest
@@ -122,12 +123,22 @@ def pytest_addoption(parser):
         metavar="GLOB",
         help="add expression for ignores when rsyncing to remote tx nodes.",
     )
-
     group.addoption(
         "--boxed",
         action="store_true",
         help="backward compatibility alias for pytest-forked --forked",
     )
+    group.addoption(
+        "--testrunuid",
+        action="store",
+        help=(
+            "provide an identifier shared amongst all workers as the value of "
+            "the 'testrun_uid' fixture,\n\n,"
+            "if not provided, 'testrun_uid' is filled with a new unique string "
+            "on every test run."
+        ),
+    )
+
     parser.addini(
         "rsyncdirs",
         "list of (relative) paths to be rsynced for remote distributed testing.",
@@ -214,3 +225,12 @@ def worker_id(request):
         return request.config.workerinput["workerid"]
     else:
         return "master"
+
+
+@pytest.fixture(scope="session")
+def testrun_uid(request):
+    """Return the unique id of the current test."""
+    if hasattr(request.config, "workerinput"):
+        return request.config.workerinput["testrunuid"]
+    else:
+        return uuid.uuid4().hex

src/xdist/remote.py

@@ -22,6 +22,7 @@ class WorkerInteractor(object):
     def __init__(self, config, channel):
         self.config = config
         self.workerid = config.workerinput.get("workerid", "?")
+        self.testrunuid = config.workerinput["testrunuid"]
         self.log = py.log.Producer("worker-%s" % self.workerid)
         if not config.option.debug:
             py.log.setconsumer(self.log._keywords, None)
@@ -112,6 +113,7 @@ class WorkerInteractor(object):
         )
         data["item_index"] = self.item_index
         data["worker_id"] = self.workerid
+        data["testrun_uid"] = self.testrunuid
         assert self.session.items[self.item_index].nodeid == report.nodeid
         self.sendevent("testreport", data=data)
 
@@ -238,6 +240,7 @@ if __name__ == "__channelexec__":
             importpath + os.pathsep + os.environ.get("PYTHONPATH", "")
         )
 
+    os.environ["PYTEST_XDIST_TESTRUNUID"] = workerinput["testrunuid"]
     os.environ["PYTEST_XDIST_WORKER"] = workerinput["workerid"]
     os.environ["PYTEST_XDIST_WORKER_COUNT"] = str(workerinput["workercount"])
 

src/xdist/workermanage.py

@@ -3,6 +3,7 @@ import fnmatch
 import os
 import re
 import sys
+import uuid
 
 import py
 import pytest
@@ -35,6 +36,9 @@ class NodeManager(object):
     def __init__(self, config, specs=None, defaultchdir="pyexecnetcache"):
         self.config = config
         self.trace = self.config.trace.get("nodemanager")
+        self.testrunuid = self.config.getoption("testrunuid")
+        if self.testrunuid is None:
+            self.testrunuid = uuid.uuid4().hex
         self.group = execnet.Group()
         if specs is None:
             specs = self._getxspecs()
@@ -222,6 +226,7 @@ class WorkerController(object):
             "workercount": len(nodemanager.specs),
             "slaveid": gateway.id,
             "slavecount": len(nodemanager.specs),
+            "testrunuid": nodemanager.testrunuid,
             "mainargv": sys.argv,
         }
         # TODO: deprecated name, backward compatibility only. Remove it in future

testing/acceptance_test.py

@@ -1066,6 +1066,29 @@ def test_worker_id_fixture(testdir, n):
         assert worker_ids == {"gw0", "gw1"}
 
 
+@pytest.mark.parametrize("n", [0, 2])
+def test_testrun_uid_fixture(testdir, n):
+    import glob
+
+    f = testdir.makepyfile(
+        """
+        import pytest
+        @pytest.mark.parametrize("run_num", range(2))
+        def test_testrun_uid1(testrun_uid, run_num):
+            with open("testrun_uid%s.txt" % run_num, "w") as f:
+                f.write(testrun_uid)
+    """
+    )
+    result = testdir.runpytest(f, "-n%d" % n)
+    result.stdout.fnmatch_lines("* 2 passed in *")
+    testrun_uids = set()
+    for fname in glob.glob(str(testdir.tmpdir.join("*.txt"))):
+        with open(fname) as f:
+            testrun_uids.add(f.read().strip())
+    assert len(testrun_uids) == 1
+    assert len(testrun_uids.pop()) == 32
+
+
 @pytest.mark.parametrize("tb", ["auto", "long", "short", "no", "line", "native"])
 def test_error_report_styles(testdir, tb):
     testdir.makepyfile(

testing/test_newhooks.py

@@ -15,7 +15,7 @@ class TestHooks:
 
     def test_runtest_logreport(self, testdir):
         """Test that log reports from pytest_runtest_logreport when running
-        with xdist contain "node", "nodeid" and "worker_id" attributes. (#8)
+        with xdist contain "node", "nodeid", "worker_id", and "testrun_uid" attributes. (#8)
         """
         testdir.makeconftest(
             """
@@ -23,20 +23,24 @@ class TestHooks:
                 if hasattr(report, 'node'):
                     if report.when == "call":
                         workerid = report.node.workerinput['workerid']
+                        testrunuid = report.node.workerinput['testrunuid']
                         if workerid != report.worker_id:
                             print("HOOK: Worker id mismatch: %s %s"
                                    % (workerid, report.worker_id))
+                        elif testrunuid != report.testrun_uid:
+                            print("HOOK: Testrun uid mismatch: %s %s"
+                                   % (testrunuid, report.testrun_uid))
                         else:
-                            print("HOOK: %s %s"
+                            print("HOOK: %s %s %s"
-                                   % (report.nodeid, report.worker_id))
+                                   % (report.nodeid, report.worker_id, report.testrun_uid))
         """
         )
         res = testdir.runpytest("-n1", "-s")
         res.stdout.fnmatch_lines(
             [
-                "*HOOK: test_runtest_logreport.py::test_a gw0*",
+                "*HOOK: test_runtest_logreport.py::test_a gw0 *",
-                "*HOOK: test_runtest_logreport.py::test_b gw0*",
+                "*HOOK: test_runtest_logreport.py::test_b gw0 *",
-                "*HOOK: test_runtest_logreport.py::test_c gw0*",
+                "*HOOK: test_runtest_logreport.py::test_c gw0 *",
                 "*3 passed*",
             ]
         )

testing/test_plugin.py

@@ -95,6 +95,18 @@ def test_dsession_with_collect_only(testdir):
     assert not config.pluginmanager.hasplugin("dsession")
 
 
+def test_testrunuid_provided(testdir):
+    config = testdir.parseconfigure("--testrunuid", "test123", "--tx=popen")
+    nm = NodeManager(config)
+    assert nm.testrunuid == "test123"
+
+
+def test_testrunuid_generated(testdir):
+    config = testdir.parseconfigure("--tx=popen")
+    nm = NodeManager(config)
+    assert len(nm.testrunuid) == 32
+
+
 class TestDistOptions:
     def test_getxspecs(self, testdir):
         config = testdir.parseconfigure("--tx=popen", "--tx", "ssh=xyz")

testing/test_remote.py

@@ -2,6 +2,7 @@ import py
 import pprint
 import pytest
 import sys
+import uuid
 
 from xdist.workermanage import WorkerController
 import execnet
@@ -44,6 +45,7 @@ class WorkerSetup:
         putevent = self.use_callback and self.events.put or None
 
         class DummyMananger:
+            testrunuid = uuid.uuid4().hex
             specs = [0, 1]
 
         self.slp = WorkerController(DummyMananger, self.gateway, config, putevent)
@@ -220,6 +222,7 @@ def test_remote_env_vars(testdir):
         """
         import os
         def test():
+            assert len(os.environ['PYTEST_XDIST_TESTRUNUID']) == 32
             assert os.environ['PYTEST_XDIST_WORKER'] in ('gw0', 'gw1')
             assert os.environ['PYTEST_XDIST_WORKER_COUNT'] == '2'
     """