feat(setup): Zope root cookie login form profile

Move the change of the default Zope root configuration from HTTP Basic auth to the
cookie login form [into a separate GenericSetup upgrade step to make the change
optional](plone/plone.restapi#1304 (comment)).

This reverts commit 132c2c390801ff16393f214c1501252b240cb62a.

src/Products/PlonePAS/profiles.zcml

@@ -21,4 +21,20 @@
     <depends name="rolemap" />
   </genericsetup:importStep>
 
+  <genericsetup:registerProfile
+      name="root-cookie"
+      title="Zope Root Cookie Login"
+      description="Change the Zope root `/acl_users` to use a simple cookie login form
+		   instead of HTTP `Basic ...` for authentication."
+      provides="Products.GenericSetup.interfaces.EXTENSION"
+      />
+  <genericsetup:importStep
+      name="zope-root-auth-cookie"
+      title="Zope Root Cookie Login"
+      description="Change the Zope root `/acl_users` to use a simple cookie login form
+		   instead of HTTP `Basic ...` for authentication."
+      handler=".setuphandlers.set_up_zope_root_cookie_auth">
+    <depends name="plonepas" />
+  </genericsetup:importStep>
+
 </configure>

src/Products/PlonePAS/profiles/root-cookie/metadata.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0"?>
+<metadata>
+  <version>1</version>
+</metadata>

src/Products/PlonePAS/profiles/root-cookie/plone-pas-zope-root-cookie.txt

@@ -0,0 +1,2 @@
+Change the Zope root `/acl_users` to use a simple cookie login form instead of HTTP
+`Basic ...` for authentication.

src/Products/PlonePAS/setuphandlers.py

@@ -1,4 +1,8 @@
 # -*- coding: utf-8 -*-
+"""
+Custom GenericSetup import steps for PAS in Plone.
+"""
+
 from Acquisition import aq_base
 from Acquisition import aq_parent
 from Products.CMFCore.utils import getToolByName
@@ -324,14 +328,9 @@ def migrate_root_uf(self):
     pas = uf.manage_addProduct['PluggableAuthService']
     plone_pas = uf.manage_addProduct['PlonePAS']
     # Setup authentication plugins
-    setupAuthPlugins(
-        parent,
-        pas,
-        plone_pas,
-        deactivate_basic_reset=False,
-        # Switch from HTTP `Authorization: Basic ...` to cookie login form
-        deactivate_cookie_challenge=False,
-    )
+    setupAuthPlugins(parent, pas, plone_pas,
+                     deactivate_basic_reset=False,
+                     deactivate_cookie_challenge=True)
 
     # Activate *all* interfaces for user manager. IUserAdder is not
     # activated for some reason by default.
@@ -518,3 +517,35 @@ def setupPlonePAS(context):
         addRolesToPlugIn(site)
         setupGroups(site)
         setLoginFormInCookieAuth(site)
+
+
+def set_up_zope_root_cookie_auth(context):
+    """
+    Change the Zope root `/acl_users` to use a simple cookie login form.
+    """
+    # Only run step if a flag file is present, IOW not for every profile
+    if context.readDataFile("plone-pas-zope-root-cookie.txt") is None:
+        return
+    portal = context.getSite()
+    root = portal.getPhysicalRoot()
+    root_acl_users = getToolByName(root, "acl_users")
+
+    # Enable the cookie plugin for all interfaces
+    activatePluginInterfaces(root, "credentials_cookie_auth")
+    # Ensure that the cookie login form is used to challenge for authentication
+    credentials_cookie_auth = root_acl_users._getOb(  # pylint: disable=protected-access
+        "credentials_cookie_auth",
+    )
+    root_acl_users.plugins.movePluginsTop(
+        IChallengePlugin,
+        [credentials_cookie_auth.id],
+    )
+    # Disable the HTTP `Basic ...` authentication plugin
+    root_acl_users.plugins.deactivatePlugin(
+        IChallengePlugin,
+        'credentials_basic_auth'
+    )
+    root_acl_users.plugins.deactivatePlugin(
+        ICredentialsResetPlugin,
+        'credentials_basic_auth'
+    )

src/Products/PlonePAS/tests/test_setup.py

@@ -29,12 +29,13 @@ def setUp(self):
         """
         self.app = self.layer["app"]
         self.root_acl_users = self.app.acl_users
+        self.portal = self.layer["portal"]
 
-    def test_zope_root_basic_challenge(self):
+    def test_zope_root_default_challenge(self):
         """
-        The Zope root `/acl_users` basic challenge plugin works.
+        The Zope root `/acl_users` default challenge plugin works.
         """
-        # Make the basic plugin the default auth challenge
+        # Check the Zope root PAS plugin configuration
         self.assertIn(
             "credentials_basic_auth",
             self.root_acl_users.objectIds(),
@@ -46,11 +47,6 @@ def test_zope_root_basic_challenge(self):
             HTTPBasicAuthHelper.HTTPBasicAuthHelper,
             "Wrong Zope root `/acl_users` basic auth plugin type",
         )
-        self.root_acl_users.plugins.movePluginsTop(
-            plugins_ifaces.IChallengePlugin,
-            [basic_plugin.id],
-        )
-        transaction.commit()
         challenge_plugins = self.root_acl_users.plugins.listPlugins(
             plugins_ifaces.IChallengePlugin,
         )
@@ -68,14 +64,18 @@ def test_zope_root_basic_challenge(self):
         self.assertEqual(
             browser.headers["Status"].lower(),
             "401 unauthorized",
-            "Wrong Zope root `/acl_users` basic challenge response status",
+            "Wrong Zope root `/acl_users` default challenge response status",
         )
 
-    def test_zope_root_default_login(self):
+    def test_zope_root_cookie_login(self):
         """
-        The Zope root `/acl_users` default login works.
+        The Zope root `/acl_users` cookie login works.
         """
-        # Check the Zope root PAS plugin configuration
+        # Install the GenericSetup profile that performs the actual switch
+        pa_testing.applyProfile(self.portal, 'Products.PlonePAS:root-cookie')
+        transaction.commit()
+
+        # Make the cookie plugin the default auth challenge
         self.assertIn(
             "credentials_cookie_auth",
             self.root_acl_users.objectIds(),