Revert "rm spec/model_update_arel_10_spec.rb"

This reverts commit 8158d2e,
restoring the test file spec/model_update_arel_10_spec.rb.

spec/model_update_arel_10_spec.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# ActiveRecord's update_all invokes compile_update for the Arel::SelectManager returned
+# by build_arel. It returns an Arel::UpdateManager. This makes sure that internal call
+# assembles the update query correctly.
+
+module Unreliable
+  class SqlTestingData
+    class_attribute :update_manager_sql
+  end
+end
+
+RSpec.describe "update_manager" do
+  it "in ActiveRecord >= 7, updates by subquery with select in random order",
+    skip: ((ActiveRecord::VERSION::MAJOR < 7) ? "test is for ActiveRecord >= 7 only" : false) do
+    module Arel
+      class SelectManager
+        def testing_compile_update(*args)
+          um = old_compile_update(*args)
+          Unreliable::SqlTestingData.update_manager_sql = um.to_sql
+          um
+        end
+        alias_method :old_compile_update, :compile_update
+        alias_method :compile_update, :testing_compile_update
+      end
+    end
+    Cat.update_all(name: "bar")
+    expect(Unreliable::SqlTestingData.update_manager_sql).to end_with("ORDER BY RANDOM())")
+    Cat.where(name: "foo").update_all(name: "bar")
+    expect(Unreliable::SqlTestingData.update_manager_sql).to end_with("ORDER BY RANDOM())")
+    Cat.where(name: "bar").order(:id).update_all(name: "baz")
+    expect(Unreliable::SqlTestingData.update_manager_sql).to end_with("ORDER BY \"cats\".\"id\" ASC)")
+  ensure
+    module Arel
+      class SelectManager
+        alias_method :compile_update, :old_compile_update
+      end
+    end
+  end
+end