diff --git a/Gemfile b/Gemfile
index d5870ad95..908c32343 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,7 +3,6 @@ source 'https://rubygems.org'
 ruby '>= 2.7.0', '< 3.3.0'
 
 gem 'rails', '7.1.2'
-gem 'rack-session', '~> 1.0'
 gem 'rouge', '~> 4.2.0'
 gem 'mini_mime', '~> 1.1.0'
 gem "actionpack-xml_parser"
diff --git a/lib/tasks/redmine.rake b/lib/tasks/redmine.rake
index aa86d3532..9d215eb72 100644
--- a/lib/tasks/redmine.rake
+++ b/lib/tasks/redmine.rake
@@ -178,32 +178,47 @@ DESC
     namespace :test do
       desc 'Runs the plugins unit tests.'
       task :units => "db:test:prepare" do |t|
-        $: << "test"
-        Rails::TestUnit::Runner.run_from_rake 'test', ["plugins/#{ENV['NAME'] || '*'}/test/unit/**/*_test.rb"]
+        pattern = "plugins/#{ENV['NAME'] || '*'}/test/unit/**/*_test.rb"
+        if Dir.glob(pattern).any?
+          $: << "test"
+          Rails::TestUnit::Runner.run_from_rake 'test', [pattern]
+        end
       end
 
       desc 'Runs the plugins functional tests.'
       task :functionals => "db:test:prepare" do |t|
-        $: << "test"
-        Rails::TestUnit::Runner.run_from_rake 'test', ["plugins/#{ENV['NAME'] || '*'}/test/functional/**/*_test.rb"]
+        pattern = "plugins/#{ENV['NAME'] || '*'}/test/functional/**/*_test.rb"
+        if Dir.glob(pattern).any?
+          $: << "test"
+          Rails::TestUnit::Runner.run_from_rake 'test', [pattern]
+        end
       end
 
       desc 'Runs the plugins integration tests.'
       task :integration => "db:test:prepare" do |t|
-        $: << "test"
-        Rails::TestUnit::Runner.run_from_rake 'test', ["plugins/#{ENV['NAME'] || '*'}/test/integration/**/*_test.rb"]
+        pattern = "plugins/#{ENV['NAME'] || '*'}/test/integration/**/*_test.rb"
+        if Dir.glob(pattern).any?
+          $: << "test"
+          Rails::TestUnit::Runner.run_from_rake 'test', [pattern]
+        end
       end
 
       desc 'Runs the plugins system tests.'
       task :system => "db:test:prepare" do |t|
-        $: << "test"
-        Rails::TestUnit::Runner.run_from_rake 'test', ["plugins/#{ENV['NAME'] || '*'}/test/system/**/*_test.rb"]
+        pattern = "plugins/#{ENV['NAME'] || '*'}/test/system/**/*_test.rb"
+        if Dir.glob(pattern).any?
+          $: << "test"
+          Rails::TestUnit::Runner.run_from_rake 'test', [pattern]
+        end
       end
 
       desc 'Runs the plugins ui tests.'
       task :ui => "db:test:prepare" do |t|
-        $: << "test"
-        Rails::TestUnit::Runner.run_from_rake 'test', ["plugins/#{ENV['NAME'] || '*'}/test/ui/**/*_test.rb"]
+        pattern = "plugins/#{ENV['NAME'] || '*'}/test/ui/**/*_test.rb"
+        if Dir.glob(pattern).any?
+          $: << "test"
+          Rails::TestUnit::Runner.run_from_rake 'test', [pattern]
+        end
       end
     end
   end
diff --git a/test/unit/project_nested_set_concurrency_test.rb b/test/unit/project_nested_set_concurrency_test.rb
index e835d2b50..077731040 100644
--- a/test/unit/project_nested_set_concurrency_test.rb
+++ b/test/unit/project_nested_set_concurrency_test.rb
@@ -38,7 +38,7 @@ class ProjectNestedSetConcurrencyTest < ActiveSupport::TestCase
     p = generate_project!
     p.destroy
 
-    assert_difference 'Project.count', 60 do
+    assert_difference 'Project.async_count.value', 60 do
       threads = []
       3.times do |i|
         threads << Thread.new(i) do