Poll for expected output.

This was the only way I could get this spec consistently working on both MRI and JRuby.

spec/io_spec.rb

@@ -57,15 +57,15 @@
   it "pumps all output" do
     10.times do |i|
       process = echo
-      
+
       out = Tempfile.new("duplex")
-      
+
       begin
         process.io.stdout = out
-        
+
         process.start
         process.poll_for_exit(exit_timeout)
-        
+
         out.rewind
         out.read.should == "hello\n"
       ensure
@@ -112,34 +112,26 @@
 
       process.start
       process.io.stdin.puts "hello"
-      sleep 0.1
-      out_receiver.read.should == "hello\n"
+
+      wait_until { rewind_and_read(out_receiver).should == "hello\n" }
 
       process.io.stdin.putc "n"
-      sleep 0.1
-      out_receiver.read.should == "n"
+      wait_until { rewind_and_read(out_receiver).should == "hello\nn" }
 
       process.io.stdin.print "e"
-      sleep 0.1
-      out_receiver.read.should == "e"
+      wait_until { rewind_and_read(out_receiver).should == "hello\nne" }
 
       process.io.stdin.printf "w"
-      sleep 0.1
-      out_receiver.read.should == "w"
+      wait_until { rewind_and_read(out_receiver).should == "hello\nnew" }
 
       process.io.stdin.write "\nworld\n"
-      sleep 0.1
-      out_receiver.read.should == "\nworld\n"
+      wait_until { rewind_and_read(out_receiver).should == "hello\nnew\nworld\n" }
 
       process.io.stdin.write_nonblock "The end\n"
-      sleep 0.1
-      out_receiver.read.should == "The end\n"
+      wait_until { rewind_and_read(out_receiver).should == "hello\nnew\nworld\nThe end\n" }
 
       process.io.stdin.close
       process.poll_for_exit(exit_timeout)
-
-      out_receiver.rewind
-      out_receiver.read.should == "hello\nnew\nworld\nThe end\n"
      ensure
       out_receiver.close
       out.close

spec/spec_helper.rb

@@ -149,13 +149,22 @@ def with_tmpdir(&blk)
 
   def wait_until(timeout = 10, &blk)
     end_time = Time.now + timeout
+    last_exception = nil
 
     until Time.now >= end_time
-      return if yield
+      begin
+        return if yield
+      rescue RSpec::Expectations::ExpectationNotMetError => ex
+        last_exception = ex
+      end
+
       sleep 0.05
     end
 
-    raise "timed out"
+    msg = "timed out after #{timeout} seconds"
+    msg << ":\n#{last_exception.message}" if last_exception
+
+    raise msg
   end
 
   def can_bind?(host, port)
@@ -165,6 +174,11 @@ def can_bind?(host, port)
     false
   end
 
+  def rewind_and_read(io)
+    io.rewind
+    io.read
+  end
+
 end # ChildProcessSpecHelper
 
 Thread.abort_on_exception = true