Add TaskTestCase

test/support/task_test_case.rb

@@ -0,0 +1,12 @@
+class TaskTestCase < ActiveSupport::TestCase
+  setup do
+    # Rake tasks usually display some results, which mixes up with test results.
+    # This suppresses default stdout and makes Rails.env.test? checks unnecessary.
+    @original_stdout = $stdout
+    $stdout = File.open(File::NULL, 'w')
+  end
+
+  teardown do
+    $stdout = @original_stdout
+  end
+end

test/test_helper.rb

@@ -12,6 +12,7 @@ require 'capybara/rails'
 require 'capybara/minitest'
 require 'webmock/minitest'
 require 'support/rails5_assertions' # Remove once upgraded to Rails 5
+require 'support/task_test_case'
 
 Setting.address_processing = false
 Setting.registry_country_code = 'US'