Documented new signal message_flashed

CHANGES

@@ -51,6 +51,7 @@ Release date to be decided.
   as intended with domain names.
 - Changed logic for picking defaults for cookie values from sessions
   to work better with Google Chrome.
+- Added `message_flashed` signal that simplifies flashing testing.
 
 Version 0.9
 -----------

docs/api.rst

@@ -524,6 +524,14 @@ Signals
    An `exc` keyword argument is passed with the exception that caused the
    teardown.
 
+.. data:: message_flashed
+
+   This signal is sent when the application is flashing a message.  The
+   messages is sent as `message` keyword argument and the category as
+   `category`.
+
+   .. versionadded:: 0.10
+
 .. currentmodule:: None
 
 .. class:: flask.signals.Namespace

docs/signals.rst

@@ -291,4 +291,22 @@ The following signals exist in Flask:
    This will also be passed an `exc` keyword argument that has a reference
    to the exception that caused the teardown if there was one.
 
+.. data:: flask.message_flashed
+   :noindex:
+
+   This signal is sent when the application is flashing a message.  The
+   messages is sent as `message` keyword argument and the category as
+   `category`.
+
+   Example subscriber::
+
+        recorded = []
+        def record(sender, message, category, **extra):
+            recorded.append((message, category))
+
+        from flask import message_flashed
+        message_flashed.connect(record, app)
+
+   .. versionadded:: 0.10
+
 .. _blinker: http://pypi.python.org/pypi/blinker