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guile/test-suite
Neil Jerram 6069e97331 Fix hanging of popen.test
The "open-output-pipe":"no duplicate" test has been hanging, on and
off, and not completely reliably, for a few years.  It's now doing so
fairly reliably for me, and investigation shows that

- the child shell process is in a tight loop (99% CPU)

- the parent Guile process is stuck calling waitpid().

The problem is that the child hasn't got the SIGPIPE that the test
intends, and so is continuing to echo "closed" forever; and Guile is
waiting for it to terminate, forever.

I haven't fully debugged the SIGPIPE problem, but it sounds very like
what Chet Ramey describes here:
http://old.nabble.com/Re%3A-SIGPIPE-not-properly-reset-with-%27trap---PIPE%27-p20985595.html.

(And my version of bash is 3.2.39.)

So, a fix should be to use something other than shell to implement the
child; and it appears that this works.

* check-guile.in (TEST_SUITE_DIR): Export.

* test-suite/tests/popen-child.scm: New script file.

* test-suite/tests/popen.test ("open-output-pipe", "no duplicate"):
  Use Guile for the child process, instead of shell.
2010-07-01 22:16:54 +01:00
..
lalr Add Boucher's lalr-scm' as the (system base lalr)' module. 2010-03-31 00:41:59 +02:00
standalone Use AM_SILENT_RULES to pare down build output, ignore auto-generated files 2010-06-18 11:15:18 +02:00
tests Fix hanging of popen.test 2010-07-01 22:16:54 +01:00
vm Clean up `test-suite/vm'. 2010-05-26 23:41:24 +02:00
ChangeLog-2008 Rename ChangeLog' files to ChangeLog-2008'. 2008-09-12 21:49:58 +02:00
guile-test deprecate has-suffix? 2010-06-11 16:58:24 +02:00
lib.scm Raise an exception upon VM stack overflows (fixes bug #29574). 2010-05-26 23:41:23 +02:00
Makefile.am Use Alex Shinn's pattern matcher for (ice-9 match). 2010-06-17 00:45:21 +02:00
README Revert "Note need for subscription to bug-guile@gnu.org." 2008-12-10 19:07:14 +00:00

This directory contains some tests for Guile, and some generic test
support code.

To run these tests, you will need a version of Guile more recent than
15 Feb 1999 --- the tests use the (ice-9 and-let*) and (ice-9
getopt-long) modules, which were added to Guile around then.

For information about how to run the test suite, read the usage
instructions in the comments at the top of the guile-test script.

You can reference the file `lib.scm' from your own code as the module
(test-suite lib); it also has comments at the top and before each
function explaining what's going on.

Please write more Guile tests, and send them to bug-guile@gnu.org.
We'll merge them into the distribution.  All test suites must be
licensed for our use under the GPL, but I don't think I'm going to
collect assignment papers for them.



Some test suite philosophy:

GDB has an extensive test suite --- around 6300 tests.  Every time the
test suite catches a bug, it's great.

GDB is so complicated that folks are often unable to get a solid
understanding of the code before making a change --- we just don't
have time.  You'll see people say things like, "Here's a fix for X; it
doesn't cause any regressions."  The subtext is, I made a change that
looks reasonable, and the test suite didn't complain, so it must be
okay.

I think this is terrible, because it suggests that the writer is using
the test suite as a substitute for having a rock-solid explanation of
why their changes are correct.  The problem is that any test suite is
woefully incomplete.  Diligent reasoning about code can catch corner
conditions or limitations that no test suite will ever find.



Jim's rule for test suites:

Every test suite failure should be a complete, mysterious surprise,
never a possibility you were prepared for.  Any other attitude
indicates that you're using the test suite as a crutch, which you need
only because your understanding is weak.