Add LoginActivity model spec and BrowserDetection concern shared example (#32959)

spec/support/examples/models/concerns/browser_detection.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+RSpec.shared_examples 'BrowserDetection' do
+  subject { described_class.new(user_agent: 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.1 Safari/605.1.15') }
+
+  describe '#detection' do
+    it 'sets a Browser instance as detection' do
+      expect(subject.detection)
+        .to be_a(Browser::Safari)
+    end
+  end
+
+  describe '#browser' do
+    it 'returns browser name from id' do
+      expect(subject.browser)
+        .to eq(:safari)
+    end
+  end
+
+  describe '#platform' do
+    it 'returns detected platform' do
+      expect(subject.platform)
+        .to eq(:mac)
+    end
+  end
+
+  describe 'Callbacks' do
+    describe 'populating the user_agent value' do
+      subject { Fabricate.build described_class.name.underscore.to_sym, user_agent: nil }
+
+      it 'changes nil to empty string' do
+        expect { subject.save }
+          .to change(subject, :user_agent).from(nil).to('')
+      end
+    end
+  end
+end