From 71dca4b60dafa87601df4ded2847411bb5b598da Mon Sep 17 00:00:00 2001
From: normal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Sat, 27 May 2017 07:23:02 +0000
Subject: test for IO.copy_stream CPU usage (r58534)

I'm likely to make similar mistakes in the future when working
on Fiber auto-scheduling.  Start adding assertions for existing
code, first.

* test/ruby/test_io.rb (test_copy_stream_no_busy_wait): added
* test/lib/test/unit/assertions.rb (assert_cpu_usage_low): added

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58924 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 test/lib/test/unit/assertions.rb | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'test/lib')

diff --git a/test/lib/test/unit/assertions.rb b/test/lib/test/unit/assertions.rb
index 976a6fd04a..92f754064a 100644
--- a/test/lib/test/unit/assertions.rb
+++ b/test/lib/test/unit/assertions.rb
@@ -715,6 +715,13 @@ eom
         skip
       end
 
+      def assert_cpu_usage_low(msg = nil, pct: 0.005)
+        require 'benchmark'
+        tms = Benchmark.measure(msg || '') { yield }
+        max = pct * tms.real
+        assert_operator tms.total, :<=, max, msg
+      end
+
       def assert_is_minus_zero(f)
         assert(1.0/f == -Float::INFINITY, "#{f} is not -0.0")
       end
-- 
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