Allow unchecking all compliance frameworks

This change fixes a bug where user can't uncheck all compliance
frameworks checkboxes under Merge Request Approvals section under
Admin area.

Rails form requires an hidden input field to be injected so if
there is no selection, it still passes the `compliance_frameworks`
parameter with empty value and sets the value correctly.

ee/app/models/ee/application_setting.rb

@@ -306,7 +306,7 @@ module EE
     end
 
     def compliance_frameworks=(values)
-      cleaned = Array.wrap(values).sort.uniq
+      cleaned = Array.wrap(values).reject(&:blank?).sort.uniq
 
       write_attribute(:compliance_frameworks, cleaned)
     end

ee/app/views/admin/push_rules/_merge_request_approvals.html.haml

@@ -27,7 +27,7 @@
             .form-text.text-muted.mb-2
               = _('The above settings apply to all projects with the selected compliance framework(s).')
 
-            = f.collection_check_boxes(:compliance_frameworks, compliance_framework_checkboxes, :first, :last, include_hidden: false) do |b|
+            = f.collection_check_boxes(:compliance_frameworks, compliance_framework_checkboxes, :first, :last) do |b|
               .form-check
                 = b.check_box(class: "form-check-input")
                 = b.label(class: "form-check-label")

ee/changelogs/unreleased/tancnle-fix-unset-all-compliance-frameworks.yml

+---
+title: Fix unchecking all compliance frameworks for MR approvals settings
+merge_request: 40070
+author:
+type: fixed

ee/spec/features/admin/admin_merge_requests_approvals_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'Admin interacts with merge requests approvals settings' do
+  include StubENV
+
+  let_it_be(:hippa) { ComplianceManagement::ComplianceFramework::FRAMEWORKS[:hipaa] }
+  let_it_be(:application_settings) { create(:application_setting, compliance_frameworks: [hippa]) }
+  let_it_be(:user) { create(:admin) }
+
+  before do
+    stub_env('IN_MEMORY_APPLICATION_SETTINGS', 'false')
+    allow(License).to receive(:feature_available?).and_return(true)
+
+    sign_in(user)
+    visit(admin_push_rule_path)
+  end
+
+  it 'updates compliance frameworks' do
+    page.within('.merge-request-approval-settings') do
+      check 'SOC 2'
+      click_button('Save changes')
+    end
+
+    visit(admin_push_rule_path)
+
+    expect(page.find_field('SOC 2')).to be_checked
+  end
+
+  it 'unsets all compliance frameworks' do
+    checkbox_selector = 'input[name="application_setting[compliance_frameworks][]"]'
+
+    page.within('.merge-request-approval-settings') do
+      page.all(checkbox_selector).each { |checkbox| checkbox.set(false) }
+
+      click_button('Save changes')
+    end
+
+    visit(admin_push_rule_path)
+
+    expect(page.all(checkbox_selector).map(&:checked?)).to all(be_falsey)
+  end
+end

ee/spec/models/application_setting_spec.rb

@@ -696,5 +696,11 @@ RSpec.describe ApplicationSetting do
 
       expect(setting.compliance_frameworks).to eq([1, 2, 3])
     end
+
+    it 'sets empty values' do
+      setting.compliance_frameworks = [""]
+
+      expect(setting.compliance_frameworks).to eq([])
+    end
   end
 end