diff --git a/last_commit.txt b/last_commit.txt
index 080151c3be..aff1765a51 100644
--- a/last_commit.txt
+++ b/last_commit.txt
@@ -1,44 +1,48 @@
-Repository: plone.app.layout
+Repository: plone.app.testing
 
 
 Branch: refs/heads/master
-Date: 2020-02-06T11:07:48+01:00
+Date: 2020-02-05T15:51:08+01:00
 Author: ale-rt (ale-rt) <alessandro.pisa@gmail.com>
-Commit: https://github.com/plone/plone.app.layout/commit/a459c8011d3c178ccd1bd9968f7534455febbc81
+Commit: https://github.com/plone/plone.app.testing/commit/e8ba5ff36f90cababf725da4a7a4b3e6c1e3120c
 
-Analytics viewlet: make webstats_js a property
+Fix some test isolation issues
 
-Analytics viewlet: make webstats_js a property, so that it does not rely on an a call to the update method to be correctly evaluated
+Fix a test isolation issue that was preventing the MOCK_MAILHOST_FIXTURE
+to be used in multiple testcases (Fixes #61),
 
-Fixes #227
+Properly configure the mail sender setting the appropriate registry
+records (Fixes #62),
+
+Adds test coverage.
 
 Files changed:
-A news/227.breaking
-M news/227.bugfix
-M plone/app/layout/analytics/tests/analytics.txt
-M plone/app/layout/analytics/view.pt
-M plone/app/layout/analytics/view.py
+A news/61.bugfix
+A news/62.bugfix
+M src/plone/app/testing/layers.py
+M src/plone/app/testing/layers.rst
+M src/plone/app/testing/tests.py
 
-b'diff --git a/news/227.breaking b/news/227.breaking\nnew file mode 100644\nindex 00000000..5d662b7a\n--- /dev/null\n+++ b/news/227.breaking\n@@ -0,0 +1 @@\n+Analytics viewlet: make webstats_js a property, so that it does not rely on an a call to the update method to be correctly evaluated [ale-rt]\ndiff --git a/news/227.bugfix b/news/227.bugfix\nindex 2d5c4765..14889926 100644\n--- a/news/227.bugfix\n+++ b/news/227.bugfix\n@@ -1 +1 @@\n-Restore compatibility with old code that was inheriting from this class and overriding the __init__ method\n+Analytics viewlet: restore compatibility with old code that was inheriting from this class and overriding the __init__ method [ale-rt]\ndiff --git a/plone/app/layout/analytics/tests/analytics.txt b/plone/app/layout/analytics/tests/analytics.txt\nindex 01deb6cc..9a914756 100644\n--- a/plone/app/layout/analytics/tests/analytics.txt\n+++ b/plone/app/layout/analytics/tests/analytics.txt\n@@ -12,8 +12,21 @@ We need a view on the content.\n Now we can instantiate the manager.\n \n     >>> manager = Footer(portal, request, view)\n+    >>> manager.update()\n+    >>> for viewlet in manager.viewlets:\n+    ...     if viewlet.__name__ == "plone.analytics":\n+    ...         analytics = viewlet\n+    ...         break\n+\n+When no analytics (webstats_js) code is set up the viewlet will not be rendered:\n+\n+    >>> analytics.webstats_js == u""\n+    True\n+    >>> text = manager.render()\n+    >>> \'id="plone-analytics"\' in text\n+    False\n \n-Set analytics (webstats_js) code through the controlpanel\n+Set the analytics code through the controlpanel and verify it renders properly:\n \n     >>> from plone.registry.interfaces import IRegistry\n     >>> from zope.component import getUtility\n@@ -21,20 +34,17 @@ Set analytics (webstats_js) code through the controlpanel\n     >>> registry = getUtility(IRegistry)\n     >>> site_settings = registry.forInterface(ISiteSchema, prefix="plone")\n     >>> site_settings.webstats_js = u"<script>window.title=\'Hello\'</script>"\n-    >>> manager.update()\n+    >>> analytics.webstats_js == site_settings.webstats_js\n+    True\n     >>> text = manager.render()\n+    >>> \'id="plone-analytics"\' in text\n+    True\n     >>> site_settings.webstats_js in text\n     True\n \n Now enter some non-ascii text\n \n     >>> site_settings.webstats_js = u"<script>window.title=\'C\\xedsa\\u0159\'</script>"\n-    >>> manager.update()\n     >>> text = manager.render()\n     >>> site_settings.webstats_js in text\n     True\n-\n-Check if the div sorrounding the script is present\n-\n-    >>> \'id="plone-analytics"\' in text\n-    True\ndiff --git a/plone/app/layout/analytics/view.pt b/plone/app/layout/analytics/view.pt\nindex ebd13fd5..7d3f83c7 100644\n--- a/plone/app/layout/analytics/view.pt\n+++ b/plone/app/layout/analytics/view.pt\n@@ -1,8 +1,7 @@\n-<div\n-  id="plone-analytics"\n-  tal:condition="view/webstats_js"\n-  tal:content="structure view/webstats_js"\n+<div id="plone-analytics"\n+     tal:define="webstats_js view/webstats_js"\n+     tal:condition="webstats_js"\n+     tal:content="structure webstats_js"\n >\n   Here goes the webstats_js\n </div>\n-\ndiff --git a/plone/app/layout/analytics/view.py b/plone/app/layout/analytics/view.py\nindex d612f8db..b45559c1 100644\n--- a/plone/app/layout/analytics/view.py\n+++ b/plone/app/layout/analytics/view.py\n@@ -16,18 +16,20 @@ class AnalyticsViewlet(BrowserView):\n     def __init__(self, context, request, view, manager):\n         super(AnalyticsViewlet, self).__init__(context, request)\n         self.__parent__ = view\n-        self.context = context\n-        self.request = request\n         self.view = view\n         self.manager = manager\n \n-    def update(self):\n-        """render the webstats snippet"""\n+    @property\n+    def webstats_js(self):\n         registry = getUtility(IRegistry)\n         site_settings = registry.forInterface(\n             ISiteSchema, prefix="plone", check=False)\n         try:\n-            if site_settings.webstats_js:\n-                self.webstats_js = site_settings.webstats_js\n+            return site_settings.webstats_js or u""\n         except AttributeError:\n-            self.webstats_js = u""\n+            return u""\n+\n+    def update(self):\n+        """ The viewlet manager _updateViewlets requires this method\n+        """\n+        pass\n'
+b'diff --git a/news/61.bugfix b/news/61.bugfix\nnew file mode 100644\nindex 0000000..fd1253d\n--- /dev/null\n+++ b/news/61.bugfix\n@@ -0,0 +1 @@\n+Fix a test isolation issue that was preventing the MOCK_MAILHOST_FIXTURE to be used in multiple testcases [ale-rt]\ndiff --git a/news/62.bugfix b/news/62.bugfix\nnew file mode 100644\nindex 0000000..4a8304d\n--- /dev/null\n+++ b/news/62.bugfix\n@@ -0,0 +1 @@\n+Properly configure the mail sender setting the appropriate registry records (Fixes #62)\ndiff --git a/src/plone/app/testing/layers.py b/src/plone/app/testing/layers.py\nindex fcc8775..b6d8a96 100644\n--- a/src/plone/app/testing/layers.py\n+++ b/src/plone/app/testing/layers.py\n@@ -13,6 +13,7 @@\n from plone.app.testing.interfaces import TEST_USER_PASSWORD\n from plone.app.testing.interfaces import TEST_USER_ROLES\n from plone.app.testing.utils import MockMailHost\n+from plone.registry.interfaces import IRegistry\n from plone.testing import Layer\n from plone.testing import zca\n from plone.testing import zodb\n@@ -20,6 +21,7 @@\n from plone.testing import zserver\n from Products.MailHost.interfaces import IMailHost\n from zope.component import getSiteManager\n+from zope.component import getUtility\n from zope.component.hooks import setSite\n from zope.event import notify\n from zope.traversing.interfaces import BeforeTraverseEvent\n@@ -382,19 +384,21 @@ class MockMailHostLayer(Layer):\n     """\n     defaultBases = (PLONE_FIXTURE,)\n \n-    def setUp(self):\n+    def testSetUp(self):\n         with zope.zopeApp() as app:\n             portal = app[PLONE_SITE_ID]\n-            portal.email_from_address = \'noreply@example.com\'\n-            portal.email_from_name = \'Plone Site\'\n+            registry = getUtility(IRegistry, context=portal)\n+            if not registry["plone.email_from_address"]:\n+                registry["plone.email_from_address"] = "noreply@example.com"\n+            if not registry["plone.email_from_name"]:\n+                registry["plone.email_from_name"] = u"Plone site"\n             portal._original_MailHost = portal.MailHost\n             portal.MailHost = mailhost = MockMailHost(\'MailHost\')\n-            portal.MailHost.smtp_host = \'localhost\'\n             sm = getSiteManager(context=portal)\n             sm.unregisterUtility(provided=IMailHost)\n             sm.registerUtility(mailhost, provided=IMailHost)\n \n-    def tearDown(self):\n+    def testTearDown(self):\n         with zope.zopeApp() as app:\n             portal = app[PLONE_SITE_ID]\n             _o_mailhost = getattr(portal, \'_original_MailHost\', None)\ndiff --git a/src/plone/app/testing/layers.rst b/src/plone/app/testing/layers.rst\nindex 49291e8..8304321 100644\n--- a/src/plone/app/testing/layers.rst\n+++ b/src/plone/app/testing/layers.rst\n@@ -379,3 +379,98 @@ When the server is torn down, the ZServer thread is stopped.\n     Traceback (most recent call last):\n     ...\n     requests.exceptions.ConnectionError: ...\n+\n+\n+Mock MailHost\n+~~~~~~~~~~~~~\n+\n+The fixture ``MOCK_MAILHOST_FIXTURE`` layer\n+allows to replace the Zope MailHost with a dummy one.\n+\n+**Note:** This layer builds on top of ``PLONE_FIXTURE``.\n+Like ``PLONE_FIXTURE``, it should only be used as a base layer,\n+and not directly in tests.\n+See this package\'s ``README`` file for details.\n+\n+    >>> layers.MOCK_MAILHOST_FIXTURE.__bases__\n+    (<Layer \'plone.app.testing.layers.PloneFixture\'>,)\n+    >>> options = runner.get_options([], [])\n+    >>> setupLayers = {}\n+    >>> runner.setup_layer(options, layers.MOCK_MAILHOST_FIXTURE, setupLayers)\n+    Set up plone.testing.zca.LayerCleanup in ... seconds.\n+    Set up plone.testing.zope.Startup in ... seconds.\n+    Set up plone.app.testing.layers.PloneFixture in ... seconds.\n+    Set up plone.app.testing.layers.MockMailHostLayer in ... seconds.\n+\n+Let\'s now simulate a test.\n+Test setup sets a couple of registry records and\n+replaces the mail host with a dummy one:\n+\n+    >>> from zope.component import getUtility\n+    >>> from plone.registry.interfaces import IRegistry\n+\n+    >>> zca.LAYER_CLEANUP.testSetUp()\n+    >>> zope.STARTUP.testSetUp()\n+    >>> layers.MOCK_MAILHOST_FIXTURE.testSetUp()\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     registry = getUtility(IRegistry, context=portal)\n+\n+    >>> registry["plone.email_from_address"]\n+    \'noreply@example.com\'\n+    >>> registry["plone.email_from_name"]\n+    \'Plone site\'\n+\n+The dummy MailHost, instead of sending the emails,\n+stores them in a list of messages:\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     portal.MailHost.messages\n+    []\n+\n+If we send a message, we can check it in the list:\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     portal.MailHost.send(\n+    ...         "Hello world!",\n+    ...         mto="foo@example.com",\n+    ...         mfrom="bar@example.com",\n+    ...         subject="Test",\n+    ...         msg_type="text/plain",\n+    ...     )\n+    >>> with helpers.ploneSite() as portal:\n+    ...     for message in portal.MailHost.messages:\n+    ...         print(message)\n+    MIME-Version: 1.0\n+    Content-Type: text/plain\n+    Subject: Test\n+    To: foo@example.com\n+    From: bar@example.com\n+    Date: ...\n+    <BLANKLINE>\n+    Hello world!\n+\n+The list can be reset:\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     portal.MailHost.reset()\n+    ...     portal.MailHost.messages\n+    []\n+\n+When the test is torn down the original MaiHost is restored:\n+\n+    >>> layers.MOCK_MAILHOST_FIXTURE.testTearDown()\n+    >>> zope.STARTUP.testTearDown()\n+    >>> zca.LAYER_CLEANUP.testTearDown()\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     portal.MailHost.messages\n+    Traceback (most recent call last):\n+    ...\n+    AttributeError: \'RequestContainer\' object has no attribute \'messages\'\n+\n+    >>> runner.tear_down_unneeded(options, [], setupLayers)\n+    Tear down plone.app.testing.layers.MockMailHostLayer in ... seconds.\n+    Tear down plone.app.testing.layers.PloneFixture in ... seconds.\n+    Tear down plone.testing.zope.Startup in ... seconds.\n+    Tear down plone.testing.zca.LayerCleanup in ... seconds.\ndiff --git a/src/plone/app/testing/tests.py b/src/plone/app/testing/tests.py\nindex 22763e1..53a7a10 100644\n--- a/src/plone/app/testing/tests.py\n+++ b/src/plone/app/testing/tests.py\n@@ -1,5 +1,6 @@\n # -*- coding: utf-8 -*-\n import doctest\n+import re\n import six\n import unittest\n \n@@ -12,18 +13,38 @@ def dummy(context):\n     pass\n \n \n+class Py23DocChecker(doctest.OutputChecker):\n+    def check_output(self, want, got, optionflags):\n+        if six.PY2:\n+            got = re.sub("u\'(.*?)\'", "\'\\\\1\'", got)\n+        return doctest.OutputChecker.check_output(self, want, got, optionflags)\n+\n+\n def test_suite():\n     suite = unittest.TestSuite()\n     # seltest = doctest.DocFileSuite(\'selenium.rst\', optionflags=OPTIONFLAGS)\n     # Run selenium tests on level 2, as it requires a correctly configured\n     # Firefox browser\n     # seltest.level = 2\n-    suite.addTests([\n-        doctest.DocFileSuite(\'cleanup.rst\', optionflags=OPTIONFLAGS),\n-        doctest.DocFileSuite(\'layers.rst\', optionflags=OPTIONFLAGS),\n-        doctest.DocFileSuite(\'helpers.rst\', optionflags=OPTIONFLAGS),\n-        # seltest,\n-    ])\n+    suite.addTests(\n+        [\n+            doctest.DocFileSuite(\n+                "cleanup.rst",\n+                optionflags=OPTIONFLAGS,\n+                checker=Py23DocChecker(),\n+            ),\n+            doctest.DocFileSuite(\n+                "layers.rst",\n+                optionflags=OPTIONFLAGS,\n+                checker=Py23DocChecker(),\n+            ),\n+            doctest.DocFileSuite(\n+                "helpers.rst",\n+                optionflags=OPTIONFLAGS,\n+                checker=Py23DocChecker(),\n+            ),\n+        ]\n+    )\n     if six.PY2:\n         suite.addTests([\n             doctest.DocFileSuite(\n'
 
-Repository: plone.app.layout
+Repository: plone.app.testing
 
 
 Branch: refs/heads/master
-Date: 2020-02-06T14:19:07+01:00
+Date: 2020-02-07T12:03:23+01:00
 Author: Maurits van Rees (mauritsvanrees) <m.van.rees@zestsoftware.nl>
-Commit: https://github.com/plone/plone.app.layout/commit/d4934fc75b473f67507e1b3c6e7452f5bbee5d81
+Commit: https://github.com/plone/plone.app.testing/commit/d0a6bdd1cf4839aeff6c283db92eb75597b42652
 
-Merge pull request #229 from plone/227-analytics-viewlet
+Merge pull request #64 from plone/isolation
 
-Analytics viewlet: make webstats_js a property
+Fix some test isolation issues
 
 Files changed:
-A news/227.breaking
-M news/227.bugfix
-M plone/app/layout/analytics/tests/analytics.txt
-M plone/app/layout/analytics/view.pt
-M plone/app/layout/analytics/view.py
+A news/61.bugfix
+A news/62.bugfix
+M src/plone/app/testing/layers.py
+M src/plone/app/testing/layers.rst
+M src/plone/app/testing/tests.py
 
-b'diff --git a/news/227.breaking b/news/227.breaking\nnew file mode 100644\nindex 00000000..5d662b7a\n--- /dev/null\n+++ b/news/227.breaking\n@@ -0,0 +1 @@\n+Analytics viewlet: make webstats_js a property, so that it does not rely on an a call to the update method to be correctly evaluated [ale-rt]\ndiff --git a/news/227.bugfix b/news/227.bugfix\nindex 2d5c4765..14889926 100644\n--- a/news/227.bugfix\n+++ b/news/227.bugfix\n@@ -1 +1 @@\n-Restore compatibility with old code that was inheriting from this class and overriding the __init__ method\n+Analytics viewlet: restore compatibility with old code that was inheriting from this class and overriding the __init__ method [ale-rt]\ndiff --git a/plone/app/layout/analytics/tests/analytics.txt b/plone/app/layout/analytics/tests/analytics.txt\nindex 01deb6cc..9a914756 100644\n--- a/plone/app/layout/analytics/tests/analytics.txt\n+++ b/plone/app/layout/analytics/tests/analytics.txt\n@@ -12,8 +12,21 @@ We need a view on the content.\n Now we can instantiate the manager.\n \n     >>> manager = Footer(portal, request, view)\n+    >>> manager.update()\n+    >>> for viewlet in manager.viewlets:\n+    ...     if viewlet.__name__ == "plone.analytics":\n+    ...         analytics = viewlet\n+    ...         break\n+\n+When no analytics (webstats_js) code is set up the viewlet will not be rendered:\n+\n+    >>> analytics.webstats_js == u""\n+    True\n+    >>> text = manager.render()\n+    >>> \'id="plone-analytics"\' in text\n+    False\n \n-Set analytics (webstats_js) code through the controlpanel\n+Set the analytics code through the controlpanel and verify it renders properly:\n \n     >>> from plone.registry.interfaces import IRegistry\n     >>> from zope.component import getUtility\n@@ -21,20 +34,17 @@ Set analytics (webstats_js) code through the controlpanel\n     >>> registry = getUtility(IRegistry)\n     >>> site_settings = registry.forInterface(ISiteSchema, prefix="plone")\n     >>> site_settings.webstats_js = u"<script>window.title=\'Hello\'</script>"\n-    >>> manager.update()\n+    >>> analytics.webstats_js == site_settings.webstats_js\n+    True\n     >>> text = manager.render()\n+    >>> \'id="plone-analytics"\' in text\n+    True\n     >>> site_settings.webstats_js in text\n     True\n \n Now enter some non-ascii text\n \n     >>> site_settings.webstats_js = u"<script>window.title=\'C\\xedsa\\u0159\'</script>"\n-    >>> manager.update()\n     >>> text = manager.render()\n     >>> site_settings.webstats_js in text\n     True\n-\n-Check if the div sorrounding the script is present\n-\n-    >>> \'id="plone-analytics"\' in text\n-    True\ndiff --git a/plone/app/layout/analytics/view.pt b/plone/app/layout/analytics/view.pt\nindex ebd13fd5..7d3f83c7 100644\n--- a/plone/app/layout/analytics/view.pt\n+++ b/plone/app/layout/analytics/view.pt\n@@ -1,8 +1,7 @@\n-<div\n-  id="plone-analytics"\n-  tal:condition="view/webstats_js"\n-  tal:content="structure view/webstats_js"\n+<div id="plone-analytics"\n+     tal:define="webstats_js view/webstats_js"\n+     tal:condition="webstats_js"\n+     tal:content="structure webstats_js"\n >\n   Here goes the webstats_js\n </div>\n-\ndiff --git a/plone/app/layout/analytics/view.py b/plone/app/layout/analytics/view.py\nindex d612f8db..b45559c1 100644\n--- a/plone/app/layout/analytics/view.py\n+++ b/plone/app/layout/analytics/view.py\n@@ -16,18 +16,20 @@ class AnalyticsViewlet(BrowserView):\n     def __init__(self, context, request, view, manager):\n         super(AnalyticsViewlet, self).__init__(context, request)\n         self.__parent__ = view\n-        self.context = context\n-        self.request = request\n         self.view = view\n         self.manager = manager\n \n-    def update(self):\n-        """render the webstats snippet"""\n+    @property\n+    def webstats_js(self):\n         registry = getUtility(IRegistry)\n         site_settings = registry.forInterface(\n             ISiteSchema, prefix="plone", check=False)\n         try:\n-            if site_settings.webstats_js:\n-                self.webstats_js = site_settings.webstats_js\n+            return site_settings.webstats_js or u""\n         except AttributeError:\n-            self.webstats_js = u""\n+            return u""\n+\n+    def update(self):\n+        """ The viewlet manager _updateViewlets requires this method\n+        """\n+        pass\n'
+b'diff --git a/news/61.bugfix b/news/61.bugfix\nnew file mode 100644\nindex 0000000..fd1253d\n--- /dev/null\n+++ b/news/61.bugfix\n@@ -0,0 +1 @@\n+Fix a test isolation issue that was preventing the MOCK_MAILHOST_FIXTURE to be used in multiple testcases [ale-rt]\ndiff --git a/news/62.bugfix b/news/62.bugfix\nnew file mode 100644\nindex 0000000..4a8304d\n--- /dev/null\n+++ b/news/62.bugfix\n@@ -0,0 +1 @@\n+Properly configure the mail sender setting the appropriate registry records (Fixes #62)\ndiff --git a/src/plone/app/testing/layers.py b/src/plone/app/testing/layers.py\nindex fcc8775..b6d8a96 100644\n--- a/src/plone/app/testing/layers.py\n+++ b/src/plone/app/testing/layers.py\n@@ -13,6 +13,7 @@\n from plone.app.testing.interfaces import TEST_USER_PASSWORD\n from plone.app.testing.interfaces import TEST_USER_ROLES\n from plone.app.testing.utils import MockMailHost\n+from plone.registry.interfaces import IRegistry\n from plone.testing import Layer\n from plone.testing import zca\n from plone.testing import zodb\n@@ -20,6 +21,7 @@\n from plone.testing import zserver\n from Products.MailHost.interfaces import IMailHost\n from zope.component import getSiteManager\n+from zope.component import getUtility\n from zope.component.hooks import setSite\n from zope.event import notify\n from zope.traversing.interfaces import BeforeTraverseEvent\n@@ -382,19 +384,21 @@ class MockMailHostLayer(Layer):\n     """\n     defaultBases = (PLONE_FIXTURE,)\n \n-    def setUp(self):\n+    def testSetUp(self):\n         with zope.zopeApp() as app:\n             portal = app[PLONE_SITE_ID]\n-            portal.email_from_address = \'noreply@example.com\'\n-            portal.email_from_name = \'Plone Site\'\n+            registry = getUtility(IRegistry, context=portal)\n+            if not registry["plone.email_from_address"]:\n+                registry["plone.email_from_address"] = "noreply@example.com"\n+            if not registry["plone.email_from_name"]:\n+                registry["plone.email_from_name"] = u"Plone site"\n             portal._original_MailHost = portal.MailHost\n             portal.MailHost = mailhost = MockMailHost(\'MailHost\')\n-            portal.MailHost.smtp_host = \'localhost\'\n             sm = getSiteManager(context=portal)\n             sm.unregisterUtility(provided=IMailHost)\n             sm.registerUtility(mailhost, provided=IMailHost)\n \n-    def tearDown(self):\n+    def testTearDown(self):\n         with zope.zopeApp() as app:\n             portal = app[PLONE_SITE_ID]\n             _o_mailhost = getattr(portal, \'_original_MailHost\', None)\ndiff --git a/src/plone/app/testing/layers.rst b/src/plone/app/testing/layers.rst\nindex 49291e8..8304321 100644\n--- a/src/plone/app/testing/layers.rst\n+++ b/src/plone/app/testing/layers.rst\n@@ -379,3 +379,98 @@ When the server is torn down, the ZServer thread is stopped.\n     Traceback (most recent call last):\n     ...\n     requests.exceptions.ConnectionError: ...\n+\n+\n+Mock MailHost\n+~~~~~~~~~~~~~\n+\n+The fixture ``MOCK_MAILHOST_FIXTURE`` layer\n+allows to replace the Zope MailHost with a dummy one.\n+\n+**Note:** This layer builds on top of ``PLONE_FIXTURE``.\n+Like ``PLONE_FIXTURE``, it should only be used as a base layer,\n+and not directly in tests.\n+See this package\'s ``README`` file for details.\n+\n+    >>> layers.MOCK_MAILHOST_FIXTURE.__bases__\n+    (<Layer \'plone.app.testing.layers.PloneFixture\'>,)\n+    >>> options = runner.get_options([], [])\n+    >>> setupLayers = {}\n+    >>> runner.setup_layer(options, layers.MOCK_MAILHOST_FIXTURE, setupLayers)\n+    Set up plone.testing.zca.LayerCleanup in ... seconds.\n+    Set up plone.testing.zope.Startup in ... seconds.\n+    Set up plone.app.testing.layers.PloneFixture in ... seconds.\n+    Set up plone.app.testing.layers.MockMailHostLayer in ... seconds.\n+\n+Let\'s now simulate a test.\n+Test setup sets a couple of registry records and\n+replaces the mail host with a dummy one:\n+\n+    >>> from zope.component import getUtility\n+    >>> from plone.registry.interfaces import IRegistry\n+\n+    >>> zca.LAYER_CLEANUP.testSetUp()\n+    >>> zope.STARTUP.testSetUp()\n+    >>> layers.MOCK_MAILHOST_FIXTURE.testSetUp()\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     registry = getUtility(IRegistry, context=portal)\n+\n+    >>> registry["plone.email_from_address"]\n+    \'noreply@example.com\'\n+    >>> registry["plone.email_from_name"]\n+    \'Plone site\'\n+\n+The dummy MailHost, instead of sending the emails,\n+stores them in a list of messages:\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     portal.MailHost.messages\n+    []\n+\n+If we send a message, we can check it in the list:\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     portal.MailHost.send(\n+    ...         "Hello world!",\n+    ...         mto="foo@example.com",\n+    ...         mfrom="bar@example.com",\n+    ...         subject="Test",\n+    ...         msg_type="text/plain",\n+    ...     )\n+    >>> with helpers.ploneSite() as portal:\n+    ...     for message in portal.MailHost.messages:\n+    ...         print(message)\n+    MIME-Version: 1.0\n+    Content-Type: text/plain\n+    Subject: Test\n+    To: foo@example.com\n+    From: bar@example.com\n+    Date: ...\n+    <BLANKLINE>\n+    Hello world!\n+\n+The list can be reset:\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     portal.MailHost.reset()\n+    ...     portal.MailHost.messages\n+    []\n+\n+When the test is torn down the original MaiHost is restored:\n+\n+    >>> layers.MOCK_MAILHOST_FIXTURE.testTearDown()\n+    >>> zope.STARTUP.testTearDown()\n+    >>> zca.LAYER_CLEANUP.testTearDown()\n+\n+    >>> with helpers.ploneSite() as portal:\n+    ...     portal.MailHost.messages\n+    Traceback (most recent call last):\n+    ...\n+    AttributeError: \'RequestContainer\' object has no attribute \'messages\'\n+\n+    >>> runner.tear_down_unneeded(options, [], setupLayers)\n+    Tear down plone.app.testing.layers.MockMailHostLayer in ... seconds.\n+    Tear down plone.app.testing.layers.PloneFixture in ... seconds.\n+    Tear down plone.testing.zope.Startup in ... seconds.\n+    Tear down plone.testing.zca.LayerCleanup in ... seconds.\ndiff --git a/src/plone/app/testing/tests.py b/src/plone/app/testing/tests.py\nindex 22763e1..53a7a10 100644\n--- a/src/plone/app/testing/tests.py\n+++ b/src/plone/app/testing/tests.py\n@@ -1,5 +1,6 @@\n # -*- coding: utf-8 -*-\n import doctest\n+import re\n import six\n import unittest\n \n@@ -12,18 +13,38 @@ def dummy(context):\n     pass\n \n \n+class Py23DocChecker(doctest.OutputChecker):\n+    def check_output(self, want, got, optionflags):\n+        if six.PY2:\n+            got = re.sub("u\'(.*?)\'", "\'\\\\1\'", got)\n+        return doctest.OutputChecker.check_output(self, want, got, optionflags)\n+\n+\n def test_suite():\n     suite = unittest.TestSuite()\n     # seltest = doctest.DocFileSuite(\'selenium.rst\', optionflags=OPTIONFLAGS)\n     # Run selenium tests on level 2, as it requires a correctly configured\n     # Firefox browser\n     # seltest.level = 2\n-    suite.addTests([\n-        doctest.DocFileSuite(\'cleanup.rst\', optionflags=OPTIONFLAGS),\n-        doctest.DocFileSuite(\'layers.rst\', optionflags=OPTIONFLAGS),\n-        doctest.DocFileSuite(\'helpers.rst\', optionflags=OPTIONFLAGS),\n-        # seltest,\n-    ])\n+    suite.addTests(\n+        [\n+            doctest.DocFileSuite(\n+                "cleanup.rst",\n+                optionflags=OPTIONFLAGS,\n+                checker=Py23DocChecker(),\n+            ),\n+            doctest.DocFileSuite(\n+                "layers.rst",\n+                optionflags=OPTIONFLAGS,\n+                checker=Py23DocChecker(),\n+            ),\n+            doctest.DocFileSuite(\n+                "helpers.rst",\n+                optionflags=OPTIONFLAGS,\n+                checker=Py23DocChecker(),\n+            ),\n+        ]\n+    )\n     if six.PY2:\n         suite.addTests([\n             doctest.DocFileSuite(\n'