Add a spec for User#requires_ldap_check?

spec/models/user_spec.rb

@@ -312,6 +312,29 @@ describe User do
     end
   end
 
+  describe :requires_ldap_check? do
+    let(:user) { User.new }
+
+    it 'is false for non-LDAP users' do
+      user.stub(ldap_user?: false)
+      expect(user.requires_ldap_check?).to be_false
+    end
+
+    context 'when the user is an LDAP user' do
+      before { user.stub(ldap_user?: true) }
+
+      it 'is true when the user has never had an LDAP check before' do
+        user.last_credential_check_at = nil
+        expect(user.requires_ldap_check?).to be_true
+      end
+
+      it 'is true when the last LDAP check happened over 1 hour ago' do
+        user.last_credential_check_at = 2.hours.ago
+        expect(user.requires_ldap_check?).to be_true
+      end
+    end
+  end
+
   describe '#full_website_url' do
     let(:user) { create(:user) }