New methods is_xdist_worker, is_xdist_master, get_xdist_worker_id. (#505)

Co-authored-by: Sylvain MARIE <sylvain.marie@se.com>
Co-authored-by: Zac Hatfield-Dodds <Zac-HD@users.noreply.github.com>
Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>

src/xdist/plugin.py

@@ -192,19 +192,53 @@ def pytest_cmdline_main(config):
 
 
 # -------------------------------------------------------------------------
-# fixtures
+# fixtures and API to easily know the role of current node
 # -------------------------------------------------------------------------
 
 
+def is_xdist_worker(request_or_session) -> bool:
+    """Return `True` if this is an xdist worker, `False` otherwise
+
+    :param request_or_session: the `pytest` `request` or `session` object
+    """
+    return hasattr(request_or_session.config, "workerinput")
+
+
+def is_xdist_master(request_or_session) -> bool:
+    """Return `True` if this is the xdist master, `False` otherwise
+
+    Note: this method also returns `False` when distribution has not been
+    activated at all.
+
+    :param request_or_session: the `pytest` `request` or `session` object
+    """
+    return (
+        not is_xdist_worker(request_or_session)
+        and request_or_session.config.option.dist != "no"
+    )
+
+
+def get_xdist_worker_id(request_or_session) -> str:
+    """Return the id of the current worker ('gw0', 'gw1', etc) or 'master'
+    if running on the 'master' node.
+
+    If not distributing tests (for example passing `-n0` or not passing `-n` at all)
+    also return 'master'.
+
+    :param request_or_session: the `pytest` `request` or `session` object
+    """
+    if hasattr(request_or_session.config, "workerinput"):
+        return request_or_session.config.workerinput["workerid"]
+    else:
+        return "master"
+
+
 @pytest.fixture(scope="session")
 def worker_id(request):
     """Return the id of the current worker ('gw0', 'gw1', etc) or 'master'
     if running on the master node.
     """
-    if hasattr(request.config, "workerinput"):
-        return request.config.workerinput["workerid"]
-    else:
-        return "master"
+    return get_xdist_worker_id(request)
 
 
 @pytest.fixture(scope="session")