Transfer warnings from workers to master

Fix #92

changelog/92.feature

@@ -0,0 +1 @@
+Warnings are now properly transferred from workers to the master node.

testing/acceptance_test.py

@@ -339,6 +339,18 @@ class TestTerminalReporting:
             "E       assert 0",
         ])
 
+    @pytest.mark.parametrize('n', ['-n0', '-n1'])
+    def test_logwarning(self, testdir, n):
+        testdir.makepyfile("""
+            import warnings
+            def test_func():
+                warnings.warn('this is a warning')
+        """)
+        result = testdir.runpytest(n)
+        result.stdout.fnmatch_lines([
+            "*this is a warning*",
+        ])
+
 
 def test_teardownfails_one_function(testdir):
     p = testdir.makepyfile("""

xdist/dsession.py

@@ -247,6 +247,11 @@ class DSession:
         if rep.failed:
             self._failed_slave_collectreport(node, rep)
 
+    def slave_logwarning(self, message, code, nodeid, fslocation):
+        """Emitted when a node calls the pytest_logwarning hook."""
+        kwargs = dict(message=message, code=code, nodeid=nodeid, fslocation=fslocation)
+        self.config.hook.pytest_logwarning.call_historic(kwargs=kwargs)
+
     def _clone_node(self, node):
         """Return new node based on an existing one.
 

xdist/remote.py

@@ -96,6 +96,9 @@ class SlaveInteractor:
         data = serialize_report(report)
         self.sendevent("collectreport", data=data)
 
+    def pytest_logwarning(self, message, code, nodeid, fslocation):
+        self.sendevent("logwarning", message=message, code=code, nodeid=nodeid, fslocation=fslocation)
+
 
 def serialize_report(rep):
     def disassembled_report(rep):

xdist/slavemanage.py

@@ -315,6 +315,10 @@ class SlaveController(object):
                 self.notify_inproc(eventname, node=self, rep=rep)
             elif eventname == "collectionfinish":
                 self.notify_inproc(eventname, node=self, ids=kwargs['ids'])
+            elif eventname == "logwarning":
+                self.notify_inproc(eventname, message=kwargs['message'],
+                                   code=kwargs['code'], nodeid=kwargs['nodeid'],
+                                   fslocation=kwargs['nodeid'])
             else:
                 raise ValueError("unknown event: %s" % (eventname,))
         except KeyboardInterrupt: