Automatic update checks (#434)

* Basic update checks

* Fix issues pointed out by @rixx

* First test

* Add tests

* Even more tests

src/tests/control/test_updatecheck.py

@@ -0,0 +1,58 @@
+import pytest
+
+from pretix.base.models import User
+from pretix.base.settings import GlobalSettingsObject
+
+
+@pytest.fixture
+def user():
+    user = User.objects.create_user('dummy@dummy.dummy', 'dummy')
+    return user
+
+
+@pytest.mark.django_db
+def test_update_notice_displayed(client, user):
+    client.login(email='dummy@dummy.dummy', password='dummy')
+
+    r = client.get('/control/')
+    assert 'pretix automatically checks for updates in the background' not in r.content.decode()
+
+    user.is_superuser = True
+    user.save()
+    r = client.get('/control/')
+    assert 'pretix automatically checks for updates in the background' in r.content.decode()
+
+    client.get('/control/global/update/')  # Click it
+    r = client.get('/control/')
+    assert 'pretix automatically checks for updates in the background' not in r.content.decode()
+
+
+@pytest.mark.django_db
+def test_settings(client, user):
+    user.is_superuser = True
+    user.save()
+    client.login(email='dummy@dummy.dummy', password='dummy')
+
+    client.post('/control/global/update/', {'update_check_email': 'test@example.org', 'update_check_perform': 'on'})
+    gs = GlobalSettingsObject()
+    gs.settings._flush()
+    assert gs.settings.update_check_perform
+    assert gs.settings.update_check_email
+
+    client.post('/control/global/update/', {'update_check_email': '', 'update_check_perform': ''})
+    gs.settings._flush()
+    assert not gs.settings.update_check_perform
+    assert not gs.settings.update_check_email
+
+
+@pytest.mark.django_db
+def test_trigger(client, user):
+    user.is_superuser = True
+    user.save()
+    client.login(email='dummy@dummy.dummy', password='dummy')
+
+    gs = GlobalSettingsObject()
+    assert not gs.settings.update_check_last
+    client.post('/control/global/update/', {'trigger': 'on'})
+    gs.settings._flush()
+    assert gs.settings.update_check_last