Enable picking a free port for ZServer layers automatically

CHANGES.rst

@@ -6,7 +6,9 @@ Changelog
 
 Breaking changes:
 
-- *add item here*
+- Default to picking a dynamical port for ZServer layers instead of a static
+  default port.
+  [Rotonen]
 
 New features:
 

src/plone/testing/z2.py

@@ -973,8 +973,10 @@ class ZServer(Layer):
 
     defaultBases = (STARTUP,)
 
-    host = os.environ.get('ZSERVER_HOST', 'localhost')
-    port = int(os.environ.get('ZSERVER_PORT', 55001))
+    # Default to 'bindall' (marked by an empty string) from os.socket
+    host = os.environ.get('ZSERVER_HOST', '')
+    # Default to letting the OS allocate us a free port (marked by 0)
+    port = int(os.environ.get('ZSERVER_PORT', 0))
     timeout = 5.0
     log = None
 
@@ -1044,6 +1046,17 @@ def setUpServer(self):
 
         self.zserver = server
 
+        # If we dynamically set the host/port, we want to reset it to localhost
+        # Otherwise this will depend on, for example, the local network setup
+        if self.host in ('', '0.0.0.0', '127.0.0.1', ):
+            self.zserver.server_name = 'localhost'
+
+        # Refresh the hostname and port in case we dynamically picked them
+        self.host = self.zserver.server_name
+        self['host'] = self.host
+        self.port = self.zserver.server_port
+        self['port'] = self.port
+
     def tearDownServer(self):
         """Close the ZServer socket
         """
@@ -1092,8 +1105,10 @@ class FTPServer(ZServer):
 
     defaultBases = (STARTUP,)
 
-    host = os.environ.get('FTPSERVER_HOST', 'localhost')
-    port = int(os.environ.get('FTPSERVER_PORT', 55002))
+    # Default to 'bindall' (marked by an empty string) from os.socket
+    host = os.environ.get('FTPSERVER_HOST', '')
+    # Default to letting the OS allocate us a free port (marked by 0)
+    port = int(os.environ.get('FTPSERVER_PORT', 0))
     threads = 1
     timeout = 5.0
     log = None
@@ -1118,6 +1133,20 @@ def setUpServer(self):
             port=self.port,
             logger_object=zopeLog)
 
+
+        # Refresh the hostname and port in case we dynamically picked them
+        self.host, self.port = self.ftpServer.socket.getsockname()
+
+        # If we dynamically set the host/port, we want to reset it to localhost
+        # Otherwise this will depend on, for example, the local network setup
+        if self.host in ('', '0.0.0.0', '127.0.0.1', ):
+            self.host = 'localhost'
+            self.ftpServer.hostname = 'localhost'
+            self.ftpServer.ip = '127.0.0.1'
+
+        self['host'] = self.host
+        self['port'] = self.port
+
     def tearDownServer(self):
         """Close the FTPServer socket
         """

src/plone/testing/z2.rst

@@ -467,13 +467,7 @@ The ``ZSERVER`` layer provides a ``FunctionalTesting`` layer that has ``ZSERVER_
 After layer setup, the resources ``host`` and ``port`` are available, and indicate where Zope is running.::
 
     >>> host = z2.ZSERVER['host']
-    >>> host
-    'localhost'
-
     >>> port = z2.ZSERVER['port']
-    >>> import os
-    >>> port == int(os.environ.get('ZSERVER_PORT', 55001))
-    True
 
 Let's now simulate a test.
 Test setup does nothing beyond what the base layers do.::
@@ -573,13 +567,7 @@ The ``FTP_SERVER`` layer is based on ``FTP_SERVER_FIXTURE``, using the ``Functio
 After layer setup, the resources ``host`` and ``port`` are available, and indicate where Zope is running.::
 
     >>> host = z2.FTP_SERVER['host']
-    >>> host
-    'localhost'
-
     >>> port = z2.FTP_SERVER['port']
-    >>> import os
-    >>> port == int(os.environ.get('FTPSERVER_PORT', 55002))
-    True
 
 Let's now simulate a test.
 Test setup does nothing beyond what the base layers do.::