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Author SHA1 Message Date
Jeff King 03763e68fb chainlint.pl: check line numbers in expected output
While working on chainlint.pl recently, we introduced some bugs that
showed incorrect line numbers in the output. But it was hard to notice,
since we sanitize the output by removing all of the line numbers! It
would be nice to retain these so we can catch any regressions.

The main reason we sanitize is for maintainability: we concatenate all
of the test snippets into a single file, so it's hard for each ".expect"
file to know at which offset its test input will be found. We can handle
that by storing the per-test line numbers in the ".expect" files, and
then dynamically offsetting them as we build the concatenated test and
expect files together.

The changes to the ".expect" files look like tedious boilerplate, but it
actually makes adding new tests easier. You can now just run:

  perl chainlint.pl chainlint/foo.test |
  tail -n +2 >chainlint/foo.expect

to save the output of the script minus the comment headers (after
checking that it is correct, of course). Whereas before you had to strip
the line numbers. The conversions here were done mechanically using
something like the script above, and then spot-checked manually.

It would be possible to do all of this in shell via the Makefile, but it
gets a bit complicated (and requires a lot of extra processes). Instead,
I've written a short perl script that generates the concatenated files
(we already depend on perl, since chainlint.pl uses it). Incidentally,
this improves a few other things:

  - we incorrectly used $(CHAINLINTTMP_SQ) inside a double-quoted
    string. So if your test directory required quoting, like:

       make "TEST_OUTPUT_DIRECTORY=/tmp/h'orrible"

    we'd fail the chainlint tests.

  - the shell in the Makefile didn't handle &&-chaining correctly in its
    loops (though in practice the "sed" and "cat" invocations are not
    likely to fail).

  - likewise, the sed invocation to strip numbers was hiding the exit
    code of chainlint.pl itself. In practice this isn't a big deal;
    since there are linter violations in the test files, we expect it to
    exit non-zero. But we could later use exit codes to distinguish
    serious errors from expected ones.

  - we now use a constant number of processes, instead of scaling with
    the number of test scripts. So it should be a little faster (on my
    machine, "make check-chainlint" goes from 133ms to 73ms).

There are some alternatives to this approach, but I think this is still
a good intermediate step:

  1. We could invoke chainlint.pl individually on each test file, and
     compare it to the expected output (and possibly using "make" to
     avoid repeating already-done checks). This is a much bigger change
     (and we'd have to figure out what to do with the "# LINT" lines in
     the inputs). But in this case we'd still want the "expect" files to
     be annotated with line numbers. So most of what's in this patch
     would be needed anyway.

  2. Likewise, we could run a single chainlint.pl and feed it all of the
     scripts (with "--jobs=1" to get deterministic output). But we'd
     still need to annotate the scripts as we did here, and we'd still
     need to either assemble the "expect" file, or break apart the
     script output to compare to each individual ".expect" file.

So we may pursue those in the long run, but this patch gives us more
robust tests without too much extra work or moving in a useless
direction.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-07-10 10:14:22 -07:00
Patrick Steinhardt 647b5e0998 tests: adjust whitespace in chainlint expectations
The "check-chainlint" target runs automatically when running tests and
performs self-checks to verify that the chainlinter itself produces the
expected output. Originally, the chainlinter was implemented via sed,
but the infrastructure has been rewritten in fb41727b7e (t: retire
unused chainlint.sed, 2022-09-01) to use a Perl script instead.

The rewrite caused some slight whitespace changes in the output that are
ultimately not of much importance. In order to be able to assert that
the actual chainlinter errors match our expectations we thus have to
ignore whitespace characters when diffing them. As the `-w` flag is not
in POSIX we try to use `git diff -w --no-index` before we fall back to
`diff -w -u`.

To accomodate for cases where the host system has no Git installation we
use the locally-compiled version of Git. This can result in problems
though when the Git project's repository is using extensions that the
locally-compiled version of Git doesn't understand. It will refuse to
run and thus cause the checks to fail.

Instead of improving the detection logic, fix our ".expect" files so
that we do not need any post-processing at all anymore. This allows us
to drop the `-w` flag when diffing so that we can always use diff(1)
now.

Note that we keep some of the post-processing of `chainlint.pl` output
intact to strip leading line numbers generated by the script. Having
these would cause a rippling effect whenever we add a new test that
sorts into the middle of existing tests and would require us to
renumerate all subsequent lines, which seems rather pointless.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-12-15 08:36:14 -08:00
Eric Sunshine 73c768dae9 chainlint: annotate original test definition rather than token stream
When chainlint detects problems in a test, such as a broken &&-chain, it
prints out the test with "?!FOO?!" annotations inserted at each problem
location. However, rather than annotating the original test definition,
it instead dumps out a parsed token representation of the test. Since it
lacks comments, indentations, here-doc bodies, and so forth, this
tokenized representation can be difficult for the test author to digest
and relate back to the original test definition.

However, now that each parsed token carries positional information, the
location of a detected problem can be pinpointed precisely in the
original test definition. Therefore, take advantage of this information
to annotate the test definition itself rather than annotating the parsed
token stream, thus making it easier for a test author to relate a
problem back to the source.

Maintaining the positional meta-information associated with each
detected problem requires a slight change in how the problems are
managed internally. In particular, shell syntax such as:

    msg="total: $(cd data; wc -w *.txt) words"

requires the lexical analyzer to recursively invoke the parser in order
to detect problems within the $(...) expression inside the double-quoted
string. In this case, the recursive parse context will detect the broken
&&-chain between the `cd` and `wc` commands, returning the token stream:

    cd data ; ?!AMP?! wc -w *.txt

However, the parent parse context will see everything inside the
double-quotes as a single string token:

    "total: $(cd data ; ?!AMP?! wc -w *.txt) words"

losing whatever positional information was attached to the ";" token
where the problem was detected.

One way to preserve the positional information of a detected problem in
a recursive parse context within a string would be to attach the
positional information to the annotation textually; for instance:

    "total: $(cd data ; ?!AMP:21:22?! wc -w *.txt) words"

and then extract the positional information when annotating the original
test definition.

However, a cleaner and much simpler approach is to maintain the list of
detected problems separately rather than embedding the problems as
annotations directly in the parsed token stream. Not only does this
ensure that positional information within recursive parse contexts is
not lost, but it keeps the token stream free from non-token pollution,
which may simplify implementation of validations added in the future
since they won't have to handle non-token "?!FOO!?" items specially.

Finally, the chainlint self-test "expect" files need a few mechanical
adjustments now that the original test definitions are emitted rather
than the parsed token stream. In particular, the following items missing
from the historic parsed-token output are now preserved verbatim:

    * indentation (and whitespace, in general)

    * comments

    * here-doc bodies

    * here-doc tag quoting (i.e. "\EOF")

    * line-splices (i.e. "\" at the end of a line)

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
2022-11-08 15:10:49 -05:00
Eric Sunshine fd4094c3ca chainlint.pl: complain about loops lacking explicit failure handling
Shell `for` and `while` loops do not terminate automatically just
because a command fails within the loop body. Instead, the loop
continues to iterate and eventually returns the exit status of the final
command of the final iteration, which may not be the command which
failed, thus it is possible for failures to go undetected. Consequently,
it is important for test authors to explicitly handle failure within the
loop body by terminating the loop manually upon failure. This can be
done by returning a non-zero exit code from within the loop body
(i.e. `|| return 1`) or exiting (i.e. `|| exit 1`) if the loop is within
a subshell, or by manually checking `$?` and taking some appropriate
action. Therefore, add logic to detect and complain about loops which
lack explicit `return` or `exit`, or `$?` check.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-09-01 10:07:41 -07:00