ux: Display error on login/registration if no auth backends are enabled.

Also makes a small tweak to CSS to ensure the styling is consistent on
the two pages.

Fixes #4525.

static/styles/portico-signin.css

@@ -68,7 +68,8 @@ html {
     width: auto;
 }
 
-.new-style .login-page-container .alert {
+.new-style .login-page-container .alert,
+.register-page-container .new-style .alert {
     margin: 0;
     text-align: left;
     font-size: 0.7em;

templates/zerver/accounts_home.html

@@ -32,6 +32,17 @@ $(function () {
             </div>
             {% endif %}
             <div class="right-side">
+                {% if no_auth_enabled %}
+                <div class="alert">
+                    <p>No authentication backends are enabled on this
+                    server yet, so it is impossible to register!</p>
+
+                    <p>See
+                    the <a href="http://zulip.readthedocs.io/en/latest/prod-install.html#step-3-configure-zulip">Zulip
+                    authentication documentation</a> to learn how to
+                    configure authentication backends.</p>
+                </div>
+                {% else %}
                 <form class="form-inline" id="send_confirm" name="email_form"
                     action="{{ current_url() }}" method="post">
                     {{ csrf_input }}
@@ -65,6 +76,8 @@ $(function () {
                     </a>
                 </div>
                 {% endif %}
+                {% endif %}
+
             </div>
         </div>
     </div>

templates/zerver/login.html

@@ -71,6 +71,17 @@ autofocus('#id_username');
         {% endif %}
 
         <div class="right-side">
+            {% if no_auth_enabled %}
+            <div class="alert">
+                <p>No authentication backends are enabled on this
+                server yet, so it is impossible to login!</p>
+
+                <p>See
+                the <a href="http://zulip.readthedocs.io/en/latest/prod-install.html#step-3-configure-zulip">Zulip
+                authentication documentation</a> to learn how to
+                configure authentication backends.</p>
+            </div>
+            {% else %}
             {% if password_auth_enabled %}
             <form name="login_form" id="login_form" method="post" class="login-form"
                   action="{{ url('django.contrib.auth.views.login') }}?next={{ next }}">
@@ -146,6 +157,7 @@ autofocus('#id_username');
                 <a class="register-link float-right" href="/register/">Register</a>
                 {% endif %}
             </div>
+            {% endif %}
         </div>
         {% endif %}
     </div>

tools/check-templates

@@ -162,6 +162,7 @@ def check_html_templates(templates, all_dups):
         'templates/corporate/zephyr.html',
         'templates/zerver/api.html',
         'templates/zerver/apps.html',
+        'templates/zerver/accounts_home.html',
         'templates/zerver/compose.html',
         'templates/zerver/emails/digest/digest_email.html',
         'templates/zerver/emails/find_team/find_team_email.html',

zerver/context_processors.py

@@ -11,6 +11,8 @@ from zproject.backends import (
     github_auth_enabled,
     google_auth_enabled,
     password_auth_enabled,
+    auth_enabled_helper,
+    AUTH_BACKEND_NAME_MAP
 )
 from zerver.lib.utils import get_subdomain
 from zerver.lib.realm_icon import get_realm_icon_url
@@ -90,6 +92,7 @@ def zulip_default_context(request):
         'google_auth_enabled': google_auth_enabled(realm),
         'github_auth_enabled': github_auth_enabled(realm),
         'any_oauth_backend_enabled': any_oauth_backend_enabled(realm),
+        'no_auth_enabled': not auth_enabled_helper(list(AUTH_BACKEND_NAME_MAP.keys()), realm),
         'development_environment': settings.DEVELOPMENT,
         'support_email': settings.ZULIP_ADMINISTRATOR,
         'find_team_link_disabled': settings.FIND_TEAM_LINK_DISABLED,

zerver/tests/test_auth_backends.py

@@ -56,7 +56,7 @@ from six.moves.http_cookies import SimpleCookie
 import ujson
 from zerver.lib.test_helpers import MockLDAP, unsign_subdomain_cookie
 
-class AuthBackendTest(TestCase):
+class AuthBackendTest(ZulipTestCase):
     email = u"hamlet@zulip.com"
 
     def get_username(self, email_to_username=None):
@@ -202,6 +202,26 @@ class AuthBackendTest(TestCase):
         with mock.patch('zproject.backends.password_auth_enabled', return_value=False):
             self.assertIsNone(EmailAuthBackend().authenticate(email, password))
 
+    @override_settings(AUTHENTICATION_BACKENDS=('zproject.backends.ZulipDummyBackend',))
+    def test_no_backend_enabled(self):
+        # type: () -> None
+        result = self.client_get('/login/')
+        self.assert_in_success_response(["No authentication backends are enabled"], result)
+
+        result = self.client_get('/register/')
+        self.assert_in_success_response(["No authentication backends are enabled"], result)
+
+    @override_settings(AUTHENTICATION_BACKENDS=('zproject.backends.GoogleMobileOauth2Backend',))
+    def test_any_backend_enabled(self):
+        # type: () -> None
+
+        # testing to avoid false error messages.
+        result = self.client_get('/login/')
+        self.assert_not_in_success_response(["No Authentication Backend is enabled."], result)
+
+        result = self.client_get('/register/')
+        self.assert_not_in_success_response(["No Authentication Backend is enabled."], result)
+
     @override_settings(AUTHENTICATION_BACKENDS=('zproject.backends.GoogleMobileOauth2Backend',))
     def test_google_backend(self):
         # type: () -> None