From 7f8ae3944c0ad68c460b3fe9c135de664206f096 Mon Sep 17 00:00:00 2001
From: hellmanj <hellmanj@ncbi.nlm.nih.gov>
Date: Tue, 23 Feb 2016 17:56:41 -0500
Subject: [PATCH] worker_id fixture as shown in #47

---
 README.rst                 | 10 ++++++++++
 testing/acceptance_test.py | 15 +++++++++++++++
 xdist/plugin.py            | 12 ++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/README.rst b/README.rst
index 54c72e4..0cbb08b 100644
--- a/README.rst
+++ b/README.rst
@@ -185,6 +185,16 @@ at once.   The specifications strings use the `xspec syntax`_.
 
 .. _`execnet`: http://codespeak.net/execnet
 
+Identifying the worker process during a test
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+If you need to determine the identity of a worker process in
+a test or fixture, you may use the ``worker_id`` fixture to do so::
+
+    @pytest.fixture()
+    def user_account(worker_id):
+        """ use a different account in each xdist worker """
+        return "account_%s" % worker_id
+
 Specifying test exec environments in an ini file
 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
diff --git a/testing/acceptance_test.py b/testing/acceptance_test.py
index c52a6da..036d187 100644
--- a/testing/acceptance_test.py
+++ b/testing/acceptance_test.py
@@ -620,3 +620,18 @@ class TestNodeFailure:
             "*Slave*crashed while running*",
             "*1 failed*2 passed*",
         ])
+
+def test_worker_id_fixture(testdir):
+    f = testdir.makepyfile("""
+        import pytest
+        @pytest.mark.parametrize("run_num", [1,2])
+        def test_worker_id1(worker_id, run_num):
+            with open("worker_id%s" % run_num, "w") as f:
+                f.write(worker_id)
+    """)
+    result = testdir.runpytest(f, "-n2")
+    worker_ids = []
+    for run_num in [1,2]:
+        worker_id_file_path = testdir.tmpdir.join("worker_id%s" % run_num).strpath
+        worker_ids.append(open(worker_id_file_path, "r").read())
+    assert "gw0" in worker_ids and "gw1" in worker_ids
diff --git a/xdist/plugin.py b/xdist/plugin.py
index 69c3a9b..c232a5e 100644
--- a/xdist/plugin.py
+++ b/xdist/plugin.py
@@ -99,3 +99,15 @@ def pytest_cmdline_main(config):
             if usepdb:
                 raise pytest.UsageError(
                     "--pdb incompatible with distributing tests.")
+
+# -------------------------------------------------------------------------
+# fixtures
+# -------------------------------------------------------------------------
+
+
+@pytest.fixture(scope="session")
+def worker_id(request):
+    if hasattr(request.config, 'slaveinput'):
+        return request.config.slaveinput['slaveid']
+    else:
+        return 'master'