prepare Automake's test suite for parallelization

[Ralf Wildenhues]

I'm not entirely happy with this one yet.  It does what is needed,
but it has warts:
- if you interrupt the test suite, you will have leftover directories,
- the check-clean stuff is supposed to be niceified in a later patch
  (i.e., made into a proper Automake interface).
- for XPASS tests we do the wrong thing: remove the test directory.
  This is because our suite's defs.in has no idea that we are running
  an XPASS.  The keep_testdirs is a cheap workaround.

I guess for the latter, check-TESTS should indicate to the test being
run that it is expected to fail.  A bit ugly.

Anyway, I'm posting it in the hope that somebody has intelligent
comments.  ;-)   Might be some days until I finally apply the patches.

FWIW, the signal stuff is stolen from Autoconf configure code.  It may
be a bit overkill, but I found the output to be a bit helpful when
reading failure logs.

FWIW2, we could use subdirectories named after the test name rather than
using the PID.  However, I've found myself running the same test in
parallel sometimes:
  make check TESTS=foo.test # Stop with C^Z, then run same command again

and it causes weird output if you later `fg' the first `make'.  Arguably
this is PEBCAK.  So really if you don't like using the PID, please speak
up, I'm all open here.

Cheers,
Ralf

    Run each test in a process-private subdirectory.  Clean up afterwards.
    
    * tests/defs.in: Employ a trap to clean up at the end of the test
    in case the test succeeded.  This needs to be revisited because we
    would like to keep the output of XPASSing tests.
    Also, note when we were interrupted by a signal.
    If $keep_testdirs is set, keep them even for successful tests.
    * tests/Makefile.am (check-clean-local): New target.  Remove all
    tests subdirs, but also make them writable first.  The latter was
    already needed without per-test subdirs.
    (distclean-local): Depend upon check-clean-local.
    * tests/Makefile.in: Regenerate.
    * HACKING: Mention `keep_testdirs'.

diff --git a/HACKING b/HACKING
index 5a3ed33..9f2f1f4 100644
--- a/HACKING
+++ b/HACKING
@@ -119,6 +119,8 @@
 
 * Make sure each test file is executable
 
+* Use `keep_testdirs=yes' to keep test directories for successful
+  tests also.
 
 ================================================================
 = Release procedure
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 5d61ae7..e915f4a 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -625,5 +625,8 @@ EXTRA_DIST = ChangeLog-old $(TESTS)
 # Each test case depends on defs, aclocal, and automake.
 check_SCRIPTS = defs aclocal-$(APIVERSION) automake-$(APIVERSION)
 
-distclean-local:
-       -rm -rf testSubDir
+distclean-local: check-clean-local
+
+check-clean-local:
+       -chmod -R a+rwx testSubDir*
+       -rm -rf testSubDir*
diff --git a/tests/Makefile.in b/tests/Makefile.in
index b9367bf..a4e0105 100644
--- a/tests/Makefile.in
+++ b/tests/Makefile.in
@@ -1000,8 +1000,11 @@ uninstall-am:
        pdf-am ps ps-am uninstall uninstall-am
 
 
-distclean-local:
-       -rm -rf testSubDir
+distclean-local: check-clean-local
+
+check-clean-local:
+       -chmod -R a+rwx testSubDir*
+       -rm -rf testSubDir*
 # Tell versions [3.59,3.63) of GNU make to not export all variables.
 # Otherwise a system limit (for SysV at least) may be exceeded.
 .NOEXPORT:
diff --git a/tests/defs.in b/tests/defs.in
index 78cf37a..2ad4345 100644
--- a/tests/defs.in
+++ b/tests/defs.in
@@ -235,16 +235,35 @@ case "$srcdir" in
     ;;
 esac
 
-chmod -R a+rwx testSubDir > /dev/null 2>&1
-rm -rf testSubDir > /dev/null 2>&1
-mkdir testSubDir
+curdir=`pwd`
+testSubDir=testSubDir$$
+chmod -R a+rwx $testSubDir > /dev/null 2>&1
+rm -rf $testSubDir > /dev/null 2>&1
+mkdir $testSubDir
+
+trap 'exit_status=$?
+  cd "$curdir"
+  case $exit_status,$keep_testdirs in
+  0,)
+    chmod -R a+rwx $testSubDir > /dev/null 2>&1
+    rm -rf "$testSubDir" ;;
+  esac
+  test "$signal" != 0 &&
+    echo "$as_me: caught signal $signal"
+  echo "$as_me: exit $exit_status"
+  exit $exit_status
+' 0
+for signal in 1 2 13 15; do
+  trap 'signal='$signal'; { (exit 1); exit 1; }' $signal
+done
+signal=0
 
 # Copy in some files we need.
 for file in install-sh missing depcomp; do
-   cp $srcdir/../lib/$file testSubDir/$file || exit 1
+   cp $srcdir/../lib/$file $testSubDir/$file || exit 1
 done
 
-cd ./testSubDir
+cd ./$testSubDir
 
 # Build appropriate environment in test directory.  Eg create
 # configure.in, touch all necessary files, etc.