Merge pull request #8797 from joshcooper/singleton_test_11236

(PUP-11236) Add ThreadLocalSingleton tests

Author: luchihoratiu

spec/unit/concurrent/thread_local_singleton_spec.rb

@@ -0,0 +1,39 @@
+require 'spec_helper'
+require 'puppet/concurrent/thread_local_singleton'
+
+class PuppetSpec::Singleton
+  extend Puppet::Concurrent::ThreadLocalSingleton
+end
+
+# Use the `equal?` matcher to ensure we get the same object
+describe Puppet::Concurrent::ThreadLocalSingleton do
+  it 'returns the same object for a single thread' do
+    expect(PuppetSpec::Singleton.singleton).to equal(PuppetSpec::Singleton.singleton)
+  end
+
+  it 'is not inherited for a newly created thread' do
+    main_thread_local = PuppetSpec::Singleton.singleton
+    Thread.new do
+      expect(main_thread_local).to_not equal(PuppetSpec::Singleton.singleton)
+    end.join
+  end
+
+  it 'does not leak outside a thread' do
+    thread_local = nil
+    Thread.new do
+      thread_local = PuppetSpec::Singleton.singleton
+    end.join
+    expect(thread_local).to_not equal(PuppetSpec::Singleton.singleton)
+  end
+
+  it 'is different for each thread' do
+    locals = []
+    Thread.new do
+      locals << PuppetSpec::Singleton.singleton
+    end.join
+    Thread.new do
+      locals << PuppetSpec::Singleton.singleton
+    end.join
+    expect(locals.first).to_not equal(locals.last)
+  end
+end