test/test_rack_hijack: ensure proper ordering of log messages

Getting the logs to show up in order is tricky in a multithreaded
server...

1 files changed, 11 insertions, 3 deletions

diff --git a/test/test_rack_hijack.rb b/test/test_rack_hijack.rb
index 2a9f23e..101f085 100644
--- a/test/test_rack_hijack.rb
+++ b/test/test_rack_hijack.rb
@@ -52,19 +52,27 @@ class TestRackHijack < Testcase
     end
     pid = mkserver(cfg)
     res = Net::HTTP.start(host, port) { |h| h.get("/hijack_req") }
+
+    wait_for_msg = lambda do |n|
+      tries = 10000
+      begin
+        Thread.new { Thread.pass }.join # calls sched_yield() on MRI
+      end until File.readlines(err.path).grep(/DieIfUsed/).size >= n ||
+                (tries -= 1) < 0
+    end
     assert_equal "request.hijacked", res.body
     assert_equal 200, res.code.to_i
     assert_equal "1.0", res.http_version
 
+    wait_for_msg.call(1)
+
     res = Net::HTTP.start(host, port) { |h| h.get("/hijack_res") }
     assert_equal "response.hijacked", res.body
     assert_equal 200, res.code.to_i
     assert_equal "zzz", res["X-Test"]
     assert_equal "1.1", res.http_version
 
-    # hope this calls sched_yield() so the forked process runs and writes
-    # to the log.
-    Thread.new { Thread.pass }.join
+    wait_for_msg.call(2)
 
     errs = File.readlines(err.path).grep(/DieIfUsed/)
     assert_equal([ "INFO #{pid} closed DieIfUsed 1\n",