Add tests, fix error handling

app/controllers/admin/legal_documents_controller.rb

@@ -5,14 +5,11 @@ module Admin
     def show
       @ld = LegalDocument.find(params[:id])
       filename = @ld.path.split('/').last
-      file = File.open(@ld.path).read
-
-      if file
+      file = File.open(@ld.path)&.read
       send_data file, filename: filename
-      else
+    rescue Errno::ENOENT
       flash[:notice] = I18n.t('legal_doc_not_found')
       redirect_to [:admin, @ld.documentable]
     end
   end
-  end
 end

test/system/admin_area/domains/legal_doc_test.rb

@@ -0,0 +1,21 @@
+require 'application_system_test_case'
+
+class AdminAreaDomainsLegalDocTest < ApplicationSystemTestCase
+  setup do
+    sign_in users(:admin)
+    @domain = domains(:shop)
+    @document = LegalDocument.create(
+      document_type: 'pdf',
+      documentable_id: @domain.id,
+      documentable_type: 'Domain',
+      path: '\zzz\zzz'
+    )
+  end
+
+  def test_absent_doc_downloading_without_errors
+    visit admin_domain_url(@domain)
+    assert_nothing_raised do
+      click_on "#{@document.created_at}"
+    end
+  end
+end