Enable notification email to work for namespaces

- link needs to provide route via group path

ee/app/views/ci_minutes_usage_mailer/notify.html.haml

 %p
-  - name_link = link_to @namespace.name, @namespace
+  - name_link = link_to @namespace.name, group_url(@namespace)
   = html_escape(_('%{name_with_link} has run out of Shared Runner Pipeline minutes so no new jobs or pipelines in its projects will run.')) % { name_with_link: name_link.html_safe }
 %p
   = _('We recommend that you buy more Pipeline minutes to resume normal service.')

ee/app/views/ci_minutes_usage_mailer/notify_limit.html.haml

 %p
-  - name_link = link_to @namespace.name, @namespace
+  - name_link = link_to @namespace.name, group_url(@namespace)
   = html_escape(_('%{name_with_link} has %{percent} or less Shared Runner Pipeline minutes remaining. Once it runs out, no new jobs or pipelines in its projects will run.')) % { name_with_link: name_link.html_safe, percent: "#{@percentage_of_available_mins}%" }
 %p
   = _('We recommend that you buy more Pipeline minutes to avoid any interruption of service.')

ee/changelogs/unreleased/220038-actionview-template-error-undefined-method-namespace_url-for-cl.yml

+---
+title: Specify group url in notification email
+merge_request: 33613
+author:
+type: fixed

ee/spec/mailers/ci_minutes_usage_mailer_spec.rb

@@ -16,27 +16,43 @@ describe CiMinutesUsageMailer do
   end
 
   describe '#notify' do
-    it_behaves_like 'mail format' do
-      let(:subject_text) do
-        "Action required: There are no remaining Pipeline minutes for #{namespace.name}"
-      end
+    let(:subject_text) do
+      "Action required: There are no remaining Pipeline minutes for #{namespace.name}"
+    end
+
+    let(:body_text) { "has run out of Shared Runner Pipeline minutes" }
 
-      let(:body_text) { "has run out of Shared Runner Pipeline minutes" }
+    subject { described_class.notify(namespace, recipients) }
 
-      subject { described_class.notify(namespace, recipients) }
+    context 'when it is a group' do
+      it_behaves_like 'mail format'
+    end
+
+    context 'when it is a namespace' do
+      it_behaves_like 'mail format' do
+        let(:namespace) { create(:namespace) }
+      end
     end
   end
 
   describe '#notify_limit' do
-    it_behaves_like 'mail format' do
-      let(:percent) { 30 }
-      let(:subject_text) do
-        "Action required: Less than #{percent}% of Pipeline minutes remain for #{namespace.name}"
-      end
+    let(:percent) { 30 }
+    let(:subject_text) do
+      "Action required: Less than #{percent}% of Pipeline minutes remain for #{namespace.name}"
+    end
+
+    let(:body_text) { "has #{percent}% or less Shared Runner Pipeline minutes" }
 
-      let(:body_text) { "has #{percent}% or less Shared Runner Pipeline minutes" }
+    subject { described_class.notify_limit(namespace, recipients, percent) }
 
-      subject { described_class.notify_limit(namespace, recipients, percent) }
+    context 'when it is a group' do
+      it_behaves_like 'mail format'
+    end
+
+    context 'when it is a namespace' do
+      it_behaves_like 'mail format' do
+        let(:namespace) { create(:namespace) }
+      end
     end
   end
 end