Domains: don't check for limit on existing domains (#12154)

Author: stsewd

readthedocs/projects/models.py

@@ -1810,7 +1810,10 @@ def restart_validation_process(self):
             self.save()
 
     def clean(self):
-        check_domains_limit(self.project)
+        # Only check the limit when creating a new domain,
+        # not when updating existing ones.
+        if not self.pk:
+            check_domains_limit(self.project)
 
     def save(self, *args, **kwargs):
         parsed = urlparse(self.domain)

readthedocs/projects/tests/test_domain_views.py

@@ -173,6 +173,47 @@ def test_create_domain_with_single_cname(self, dns_resolve_mock):
         domain = self.project.domains.first()
         assert domain.domain == "docs.example.com"
 
+    @override_settings(
+        RTD_DEFAULT_FEATURES=dict(
+            [RTDProductFeature(type=TYPE_CNAME, value=1).to_item()]
+        ),
+    )
+    @mock.patch("readthedocs.projects.forms.dns.resolver.resolve")
+    def test_domains_limit(self, dns_resolve_mock):
+        dns_resolve_mock.side_effect = dns.resolver.NoAnswer
+        assert self.project.domains.count() == 0
+
+        # Create the first domain
+        resp = self.client.post(
+            reverse("projects_domains_create", args=[self.project.slug]),
+            data={"domain": "test1.example.com"},
+        )
+        assert resp.status_code == 302
+        assert self.project.domains.count() == 1
+
+        # Create the second domain
+        resp = self.client.post(
+            reverse("projects_domains_create", args=[self.project.slug]),
+            data={"domain": "test2.example.com"},
+        )
+        assert resp.status_code == 200
+        form = resp.context_data["form"]
+        assert not form.is_valid()
+        assert "has reached the limit" in form.errors["__all__"][0]
+        assert self.project.domains.count() == 1
+
+        # Edit the existing domain
+        domain = self.project.domains.first()
+        assert not domain.canonical
+        resp = self.client.post(
+            reverse("projects_domains_edit", args=[self.project.slug, domain.pk]),
+            data={"canonical": True},
+        )
+        assert resp.status_code == 302
+        assert self.project.domains.count() == 1
+        domain = self.project.domains.first()
+        assert domain.canonical
+
 
 @override_settings(RTD_ALLOW_ORGANIZATIONS=True)
 class TestDomainViewsWithOrganizations(TestDomainViews):