Add tests for Queue#pop with fiber scheduler. (#6953)

Merged-By: ioquatix <samuel@codeotaku.com>

test/fiber/test_queue.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+require 'test/unit'
+require_relative 'scheduler'
+
+class TestFiberQueue < Test::Unit::TestCase
+  def test_pop_with_timeout
+    queue = Thread::Queue.new
+    result = :unspecified
+
+    Thread.new do
+      scheduler = Scheduler.new
+      Fiber.set_scheduler(scheduler)
+
+      Fiber.schedule do
+        result = queue.pop(timeout: 0.0001)
+      end
+
+      scheduler.run
+    end.join
+
+    assert_nil result
+  end
+
+  def test_pop_with_timeout_and_value
+    queue = Thread::Queue.new
+    queue.push(:something)
+    result = :unspecified
+
+    Thread.new do
+      scheduler = Scheduler.new
+      Fiber.set_scheduler(scheduler)
+
+      Fiber.schedule do
+        result = queue.pop(timeout: 0.0001)
+      end
+
+      scheduler.run
+    end.join
+
+    assert_equal :something, result
+  end
+end