The annotations emitted by chainlint to indicate detected problems are
overly terse, so much so that developers new to the project -- those who
should most benefit from the linting -- may find them baffling. For
instance, although the author of chainlint and seasoned Git developers
may understand that "?!AMP?!" is an abbreviation of "ampersand" and
indicates a break in the &&-chain, this may not be obvious to newcomers.
The "?!LOOP?!" case is particularly serious because that terse single
word does nothing to convey that the loop body should end with
"|| return 1" (or "|| exit 1" in a subshell) to ensure that a failing
command in the body aborts the loop immediately. Moreover, unlike
&&-chaining which is ubiquitous in Git tests, the "|| return 1" idiom is
relatively infrequent, thus may be harder for a newcomer to discover by
consulting nearby code.
Address these shortcomings by emitting human-readable messages which
both explain the problem and give a strong hint about how to correct it.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
An unclosed here-doc in a test is a problem, because it silently gobbles
up any remaining commands. Since 99a64e4b73 (tests: lint for run-away
here-doc, 2017-03-22) we detect this by piggy-backing on the internal
chainlint checker in test-lib.sh.
However, it would be nice to detect it in chainlint.pl, for a few
reasons:
- the output from chainlint.pl is much nicer; it can show the exact
spot of the error, rather than a vague "somewhere in this test you
broke the &&-chain or had a bad here-doc" message.
- the implementation in test-lib.sh runs for each test snippet. And
since it requires a subshell, the extra cost is small but not zero.
If chainlint.pl can reliably find the problem, we can optimize the
test-lib.sh code.
The chainlint.pl code never intended to find here-doc problems. But
since it has to parse them anyway (to avoid reporting problems inside
here-docs), most of what we need is already there. We can detect the
problem when we fail to find the missing end-tag in swallow_heredocs().
The extra change in scan_heredoc_tag() stores the location of the start
of the here-doc, which lets us mark it as the source of the error in the
output (see the new tests for examples).
[jk: added commit message and tests]
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Eric Sunshine