Add a simple test mode (#1181)

- [x] Provide data model and configuration toggle
- [x] Allow to delete individual test orders
- [x] Add tests
- [x] Add a prominent warning message to the backend if test mode orders exist (even though test mode is off), as this leads to wrong statistics
- [x] Decide if and how to generate invoices for test orders as invoice numbers cannot be repeated or should not have gaps.
- [x] Decide if and how we expose test orders through the API, since our difference pull mechanism relies on the fact that orders cannot be deleted.
- [x] Decide if and how we want to couple test modes of payment providers?
- [ ] pretix.eu: Ignore test orders for billing
- [ ] Adjust payment providers: Mollie, bitpay, cash, fakepayment, sepadebit

![download](https://user-images.githubusercontent.com/64280/53009081-fe420d80-343a-11e9-8361-b8511c988598.png)

src/tests/control/test_orders.py

@@ -126,6 +126,15 @@ def test_order_list(client, env):
     response = client.get('/control/event/dummy/dummy/orders/?question=%d&answer=%d' % (q.pk, qo2.pk))
     assert 'FOO' not in response.rendered_content
 
+    response = client.get('/control/event/dummy/dummy/orders/?status=testmode')
+    assert 'FOO' not in response.rendered_content
+    assert 'TEST MODE' not in response.rendered_content
+    env[2].testmode = True
+    env[2].save()
+    response = client.get('/control/event/dummy/dummy/orders/?status=testmode')
+    assert 'FOO' in response.rendered_content
+    assert 'TEST MODE' in response.rendered_content
+
 
 @pytest.mark.django_db
 def test_order_detail(client, env):
@@ -134,6 +143,16 @@ def test_order_detail(client, env):
     assert 'Early-bird' in response.rendered_content
     assert 'Peter' in response.rendered_content
     assert 'Lukas Gelöscht' in response.rendered_content
+    assert 'TEST MODE' not in response.rendered_content
+
+
+@pytest.mark.django_db
+def test_order_detail_show_test_mode(client, env):
+    env[2].testmode = True
+    env[2].save()
+    client.login(email='dummy@dummy.dummy', password='dummy')
+    response = client.get('/control/event/dummy/dummy/orders/FOO/')
+    assert 'TEST MODE' in response.rendered_content
 
 
 @pytest.mark.django_db
@@ -260,6 +279,26 @@ def test_order_deny(client, env):
     assert o.require_approval
 
 
+@pytest.mark.django_db
+def test_order_delete_require_testmode(client, env):
+    client.login(email='dummy@dummy.dummy', password='dummy')
+    res = client.get('/control/event/dummy/dummy/orders/FOO/delete', {}, follow=True)
+    assert 'alert-danger' in res.rendered_content
+    assert 'Only orders created in test mode can be deleted' in res.rendered_content
+    client.post('/control/event/dummy/dummy/orders/FOO/delete', {}, follow=True)
+    assert Order.objects.get(id=env[2].id)
+
+
+@pytest.mark.django_db
+def test_order_delete(client, env):
+    o = Order.objects.get(id=env[2].id)
+    o.testmode = True
+    o.save()
+    client.login(email='dummy@dummy.dummy', password='dummy')
+    client.post('/control/event/dummy/dummy/orders/FOO/delete', {}, follow=True)
+    assert not Order.objects.filter(id=env[2].id).exists()
+
+
 @pytest.mark.django_db
 @pytest.mark.parametrize("process", [
     # (Old status, new status, success expected)