Fix a race condition in Action Text's test suite

`assert_queries` in Action Text's test helpers can detect queries from
a previous test if background jobs are allowed to run during its
execution.

Changing the queue_adapter to the test adapter for all tests using the
helper ensure no jobs can run during its execution.

actiontext/test/test_helper.rb

@@ -24,21 +24,25 @@
 end
 
 class ActiveSupport::TestCase
-  def assert_queries(expected_count, &block)
-    ActiveRecord::Base.connection.materialize_transactions
+  module QueryHelpers
+    include ActiveJob::TestHelper
 
-    queries = []
-    ActiveSupport::Notifications.subscribe("sql.active_record") do |*, payload|
-      queries << payload[:sql] unless %w[ SCHEMA TRANSACTION ].include?(payload[:name])
-    end
+    def assert_queries(expected_count, &block)
+      ActiveRecord::Base.connection.materialize_transactions
 
-    result = _assert_nothing_raised_or_warn("assert_queries", &block)
-    assert_equal expected_count, queries.size, "#{queries.size} instead of #{expected_count} queries were executed. #{queries.inspect}"
-    result
-  end
+      queries = []
+      ActiveSupport::Notifications.subscribe("sql.active_record") do |*, payload|
+        queries << payload[:sql] unless %w[ SCHEMA TRANSACTION ].include?(payload[:name])
+      end
 
-  def assert_no_queries(&block)
-    assert_queries(0, &block)
+      result = _assert_nothing_raised_or_warn("assert_queries", &block)
+      assert_equal expected_count, queries.size, "#{queries.size} instead of #{expected_count} queries were executed. #{queries.inspect}"
+      result
+    end
+
+    def assert_no_queries(&block)
+      assert_queries(0, &block)
+    end
   end
 
   private

actiontext/test/unit/model_test.rb

@@ -3,6 +3,8 @@
 require "test_helper"
 
 class ActionText::ModelTest < ActiveSupport::TestCase
+  include QueryHelpers
+
   test "html conversion" do
     message = Message.new(subject: "Greetings", content: "<h1>Hello world</h1>")
     assert_equal %Q(<div class="trix-content">\n  <h1>Hello world</h1>\n</div>\n), "#{message.content}"