patch 7.4.1501
Problem:    Garbage collection with an option channel is not tested.
Solution:   Call garbagecollect() in the test.
diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index 3bdfd4c..31a4ff6 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -146,6 +146,9 @@
   endif
   call assert_equal('got it', s:responseMsg)
 
+  " Collect garbage, tests that our handle isn't collected.
+  call garbagecollect()
+
   " check setting options (without testing the effect)
   call ch_setoptions(handle, {'callback': 's:NotUsed'})
   call ch_setoptions(handle, {'timeout': 1111})