test_mogilefs: improve test completeness/docs

This test needs to keep the socket alive on the server to ensure
the client can drop the connection.

We also need to ensure the test fails if the following change is
made:

  --- a/lib/mogilefs/backend.rb
  +++ b/lib/mogilefs/backend.rb
  @@ -255,7 +255,7 @@ def do_request(cmd, args, idempotent = false)
           end
           shutdown_unlocked(true)
         rescue MogileFS::UnreadableSocketError, MogileFS::Timeout
  -        shutdown_unlocked(true)
  +        # shutdown_unlocked(true)
         rescue
           # we DO NOT want the response we timed out waiting for, to crop up later
           # on, on the same socket, intersperesed with a subsequent request!  we

Thanks to David Rasch for inspiring this change.

1 files changed, 19 insertions, 9 deletions

diff --git a/test/test_mogilefs.rb b/test/test_mogilefs.rb
index 439a045..247feca 100644
--- a/test/test_mogilefs.rb
+++ b/test/test_mogilefs.rb
@@ -616,10 +616,14 @@ class TestMogileFS__MogileFS < TestMogileFS
     received = []
     secs = timeout + 1
     th = Thread.new do
+      close_later = []
       x = a.accept
+      close_later << x
       line = x.gets
       %r{key=(\w+)} =~ line
-      sleep(secs)
+
+      sleep(secs) # cause the client to timeout:
+
       begin
         x.write("OK paths=1&path1=http://0/#{$1}\r\n")
       rescue Errno::EPIPE
@@ -627,21 +631,26 @@ class TestMogileFS__MogileFS < TestMogileFS
         # we don't care either way
       rescue => e
         flunk("#{e.message} (#{e.class})")
-      ensure
-        x.close
       end
       q << :continue_test
 
-      x = a.accept
-      line = x.gets
+      # client should start a new connection here
+      y = a.accept
+      close_later << y
+      line = y.gets
       %r{key=(\w+)} =~ line
       begin
-        x.write("OK paths=1&path1=http://0/#{$1}\r\n")
+        y.write("OK paths=1&path1=http://0/#{$1}\r\n")
       rescue => e
         flunk("#{e.message} (#{e.class})")
-      ensure
-        x.close
       end
+
+      # the client should've killed the old connection:
+      assert_raises(Errno::EPIPE) do
+        loop { x.write("OK paths=1&path1=http://0/#{$1}\r\n") }
+      end
+
+      close_later # main thread closes
     end
     assert_raises(MogileFS::UnreadableSocketError) do
       c.get_paths("a")
@@ -650,7 +659,8 @@ class TestMogileFS__MogileFS < TestMogileFS
     expect2 = %w(http://0/b)
     assert_equal expect2, c.get_paths("b")
     a.close
-    th.join
+    close_later = th.value
+    close_later.each { |io| assert_nil io.close }
   end
 
   def test_idempotent_command_response_truncated