* jk/wrap-perl-used-in-tests:
  t: use perl instead of "$PERL_PATH" where applicable
  t: provide a perl() function which uses $PERL_PATH

Once upon a time, we assumed that calling a bare "perl" in
the test scripts was OK, because we would find the perl from
the user's PATH, and we were only asking that perl to do
basic operations that work even on old versions of perl.

Later, we found that some systems really prefer to use
$PERL_PATH even for these basic cases, because the system
perl misbehaves in some way (e.g., by handling line endings
differently). We then switched "perl" invocations to
"$PERL_PATH" to respect the user's choice.

Having to use "$PERL_PATH" is ugly and cumbersome, though.
Instead, let's provide a perl() shell function that tests
can use, which will transparently do the right thing.

Unfortunately, test writers still have to use $PERL_PATH in
certain situations, so we still need to keep the advice in
the README.

Note that this may fix test failures in t5004, t5503, t6002,
t6003, t6300, t8001, and t8002, depending on your system's
perl setup. All of these can be detected by running:

  ln -s /bin/false bin-wrappers/perl
  make test

which fails before this patch, and passes after.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The git build system supports a NO_PERL switch to avoid installing
perl bindings or other features (like "git add --patch") that rely on
perl on runtime, but even with NO_PERL it has not been possible for a
long time to run tests without perl.  Helpers such as

	nul_to_q () {
		"$PERL_PATH" -pe 'y/\000/Q/'
	}

use perl as a better tr or sed and are regularly used in tests without
worrying to add a PERL prerequisite.

Perl is portable enough that it seems fine to keep relying on it for
this kind of thing in tests (and more readable than the alternative of
trying to find POSIXy equivalents).  Update the test documentation to
clarify this.

Reported-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Allows N instances of tests run in parallel, each running 1/N parts
of the test suite under Valgrind, to speed things up.

* tr/test-v-and-v-subtest-only:
  perf-lib: fix start/stop of perf tests
  test-lib: support running tests under valgrind in parallel
  test-lib: allow prefixing a custom string before "ok N" etc.
  test-lib: valgrind for only tests matching a pattern
  test-lib: verbose mode for only tests matching a pattern
  test-lib: self-test that --verbose works
  test-lib: rearrange start/end of test_expect_* and test_skip
  test-lib: refactor $GIT_SKIP_TESTS matching
  test-lib: enable MALLOC_* for the actual tests

With the new --valgrind-only=<pattern> option, one can enable
--valgrind at a per-test granularity, exactly analogous to
--verbose-only from the previous commit.

The options are wired such that --valgrind implies --verbose (as
before), but --valgrind-only=<pattern> implies
--verbose-only=<pattern> unless --verbose is also in effect.

Signed-off-by: Thomas Rast <trast@inf.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

With the new --verbose-only=<pattern> option, one can enable --verbose
at a per-test granularity.  The pattern is matched against the test
number, e.g.

  ./t0000-basic.sh --verbose-only='2[0-2]'

to see only the full output of test 20-22, while showing the rest in the
one-liner format.

As suggested by Jeff King, this takes care to wrap the entire
test_expect_* block, but nothing else, in the verbose toggling.  We
can use the test_start/end functions from the previous commit for the
purpose.

This is arguably not *too* useful on its own, but makes the next patch
easier to follow.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Thomas Rast <trast@inf.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Many tests that check the behaviour of symbolic links stored in the
index or the tree objects do not have to be skipped on a filesystem
that lack symbolic link support.

* js/test-ln-s-add:
  t4011: remove SYMLINKS prerequisite
  t6035: use test_ln_s_add to remove SYMLINKS prerequisite
  t3509, t4023, t4114: use test_ln_s_add to remove SYMLINKS prerequisite
  t3100: use test_ln_s_add to remove SYMLINKS prerequisite
  t3030: use test_ln_s_add to remove SYMLINKS prerequisite
  t0000: use test_ln_s_add to remove SYMLINKS prerequisite
  tests: use test_ln_s_add to remove SYMLINKS prerequisite (trivial cases)
  tests: introduce test_ln_s_add
  t3010: modernize style
  test-chmtime: Fix exit code on Windows

Add a new function that creates a symbolic link and adds it to the index
to be used in cases where a symbolic link is not required on the file
system. We will use it to remove many SYMLINKS prerequisites from test
cases.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

When a test wants to make sure there is no <string> in an output
file, we should just say "! grep string output".

"test_must_fail" is there only to test Git command and catch unusual
deaths we know about (e.g. segv) as an error, not as an expected
failure.  "test_must_fail grep string output" is unnecessary, as
we are not making sure the system binaries do not dump core or
anything like that.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

* maint:
  Typo fix: replacing it's -> its
  t: make PIPE a standard test prerequisite
  archive: clarify explanation of --worktree-attributes
  t/README: --immediate skips cleanup commands for failed tests