1 files changed, 69 insertions, 0 deletions
diff --git a/spec/ruby/library/conditionvariable/signal_spec.rb b/spec/ruby/library/conditionvariable/signal_spec.rb
new file mode 100644
index 0000000000..38bee8984b
--- /dev/null
+++ b/spec/ruby/library/conditionvariable/signal_spec.rb
@@ -0,0 +1,69 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require 'thread'
+
+describe "ConditionVariable#signal" do
+  it "returns self if nothing to signal" do
+    cv = ConditionVariable.new
+    cv.signal.should == cv
+  end
+
+  it "returns self if something is waiting for a signal" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    in_synchronize = false
+
+    th = Thread.new do
+      m.synchronize do
+        in_synchronize = true
+        cv.wait(m)
+      end
+    end
+
+    # wait for m to acquire the mutex
+    Thread.pass until in_synchronize
+    # wait until th is sleeping (ie waiting)
+    Thread.pass while th.status and th.status != "sleep"
+
+    m.synchronize { cv.signal }.should == cv
+
+    th.join
+  end
+
+  it "releases the first thread waiting in line for this resource" do
+    m = Mutex.new
+    cv = ConditionVariable.new
+    threads = []
+    r1 = []
+    r2 = []
+
+    # large number to attempt to cause race conditions
+    100.times do |i|
+      threads << Thread.new(i) do |tid|
+        m.synchronize do
+          r1 << tid
+          cv.wait(m)
+          r2 << tid
+        end
+      end
+    end
+
+    # wait for all threads to acquire the mutex the first time
+    Thread.pass until m.synchronize { r1.size == threads.size }
+    # wait until all threads are sleeping (ie waiting)
+    Thread.pass until threads.all? {|th| th.status == "sleep" }
+
+    r2.should be_empty
+    100.times do |i|
+      m.synchronize do
+        cv.signal
+      end
+      Thread.pass until r2.size == i+1
+    end
+
+    threads.each {|t| t.join }
+
+    # ensure that all the threads that went into the cv.wait are
+    # released in the same order
+    r2.should == r1
+  end
+end