(maybe) zsh-related bug in tests/defs.in

[Stefano Lattarini]

Hi everybody.

I found what follows using the latest automake from the git
repository, on my debian unstable system.

While trying to run the automake testsuite *in parallel*, using
zsh (version 4.3), I ran into some apparently random failures
(with most test scripts failing), which I tracked down to the
way $testSubDir is defined in `tests/defs.in'.

In fact, in `tests/defs.in' there are the following definitions:
  me=`echo "$0" | sed -e 's,.*[\\/],,;s/\.test$//'`
  testSubDir=$me.dir
Thus one would expect that, if `test.foo' does the customary:
  ./defs || Exit 1
then it ends up defining `$me' to `foo' and $testSubDir to `foo.dir'.

Unfortunately, this is not the case with zsh.

By default, in a sourced script, zsh set $0 to the path of that
same sourced script -- more info at:
  http://zsh.dotsrc.org/Doc/Release/Parameters.html#IDX166
This problem *seems* to be taken care of in `defs.in' itself, by the
command `emulate sh', but unfortunately this command is issued
too late. 

In fact, when `foo.test' includes `./defs', it isn't in "emulate sh"
mode yet, so that in `./defs' tha value of $0 remains set to
`./defs', no matter if the sh-compatibility mode is later
activated.  Thus $me is *always* set to `defs' and $testSubDir
is *always* set to `defs.dir'.  D'oh.

Some commands showing this problem in action:
 $ git clone git://git.savannah.gnu.org/automake.git
 $ cd automake
 $ ./bootstrap && ./configure
 $ cd tests
 $ cat >foo.test <<'EOF'
 . ./defs || exit 100
 test x"$me" = x"foo" || Exit 1
 Exit 0
 EOF
 $ bash foo.test
 === Running test foo.test
 ++ pwd
 /tmp/automake/tests/foo.dir
+ test xfoo = xfoo
+ Exit 0
 ...
 : exit 0
 + exit 0
 $ dash foo.test
 === Running test foo.test
 + pwd
 /tmp/automake/tests/foo.dir
 + test xfoo = xfoo
 + Exit 0
 ...
 : exit 0
 + exit 0
 $ zsh foo.test
 === Running test ./defs
 +./defs:427> pwd
 /tmp/automake/tests/defs.dir
 +foo.test:2> test xdefs '=' xfoo
 +foo.test:2> Exit 1
 +Exit:2> set +e
 +Exit:3> exit 1
 +Exit:4> exit 1
 +foo.test:2> exit_status=1
 +foo.test:2> set +e
 +foo.test:2> cd /tmp/automake/tests
 +foo.test:2> case 1, (0,)
 +foo.test:2> test 0 '!=' 0
 +foo.test:2> echo ': exit 1'
 : exit 1
 +foo.test:2> exit 1

- - -

I'm not sure if this can be truly classified as a bug, since the
test scripts all have a `#!/bin/sh' shebang line, and I hope
that few people or systems are crazy enough to use zsh as
their default Bourne shell.  Anyway, this problem might deserve
some consideration.

Regards,
     Stefano