Allow executor extensions to publish events (#686)

The active executor extension already has a private variable holding the
event controller, so it's not difficult to add a method to allow
implementations of the executor extensions to publish events as well.

Author: cottsay

colcon_core/executor/__init__.py

@@ -141,7 +141,7 @@ class ExecutorExtensionPoint:
     """
 
     """The version of the executor extension interface."""
-    EXTENSION_POINT_VERSION = '1.0'
+    EXTENSION_POINT_VERSION = '1.1'
 
     """The default priority of executor extensions."""
     PRIORITY = 100
@@ -191,6 +191,14 @@ def execute(
         """
         raise NotImplementedError()
 
+    def put_event_into_queue(self, event):
+        """
+        Post a message event into the event queue.
+
+        :param event: The event
+        """
+        self._event_controller.get_queue().put((event, self))
+
     def _flush(self):
         if self._event_controller is None:
             return

test/test_executor.py

@@ -123,9 +123,12 @@ def test_interface():
     interface = ExecutorExtensionPoint()
     interface._flush()
     event_controller = Mock()
+    event_controller.get_queue.returns = Mock()
     interface.set_event_controller(event_controller)
+    interface.put_event_into_queue(object())
     interface._flush()
     assert event_controller.flush.call_count == 1
+    assert event_controller.get_queue().put.call_count == 1
 
 
 class Extension1(ExecutorExtensionPoint):