describe :mutex_locked, :shared => true do
  it "returns true if locked" do
    m = Mutex.new
    m.lock
    m.locked?.should be_true
  end

  it "returns false if unlocked" do
    m = Mutex.new
    m.locked?.should be_false
  end

  it "returns the status of the lock" do
    m1 = Mutex.new
    m2 = Mutex.new

    m2.lock # hold th with only m1 locked
    m1_locked = false

    th = Thread.new do
      m1.lock
      m1_locked = true
      m2.lock
    end

    Thread.pass until m1_locked

    m1.locked?.should be_true
    m2.unlock # release th
    th.join
    m1.locked?.should be_false
  end
end