During the development of chainlint.pl, numerous new self-tests were
created to verify correct functioning beyond the checks already
represented by the existing self-tests. The new checks fall into several
categories:
* behavior of the lexical analyzer for complex cases, such as line
splicing, token pasting, entering and exiting string contexts inside
and outside of test script bodies; for instance:
test_expect_success 'title' '
x=$(echo "something" |
sed -e '\''s/\\/\\\\/g'\'' -e '\''s/[[/.*^$]/\\&/g'\''
'
* behavior of the parser for all compound grammatical constructs, such
as `if...fi`, `case...esac`, `while...done`, `{...}`, etc., and for
other legal shell grammatical constructs not covered by existing
chainlint.sed self-tests, as well as complex cases, such as:
OUT=$( ((large_git 1>&3) | :) 3>&1 ) &&
* detection of problems, such as &&-chain breakage, from top-level to
any depth since the existing self-tests do not cover any top-level
context and only cover subshells one level deep due to limitations of
chainlint.sed
* address blind spots in chainlint.sed (such as not detecting a broken
&&-chain on a one-line for-loop in a subshell[1]) which chainlint.pl
correctly detects
* real-world cases which tripped up chainlint.pl during its development
[1]: https://lore.kernel.org/git/dce35a47012fecc6edc11c68e91dbb485c5bc36f.1661663880.git.gitgitgadget@gmail.com/
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The purpose of chainlint.sed is to detect &&-chain breakage only within
subshells (one level deep); it doesn't bother checking for top-level
&&-chain breakage since the &&-chain checker built into t/test-lib.sh
should detect broken &&-chains outside of subshells by making them
magically exit with code 117. However, this division of labor may not
always be the case if a more capable chainlint implementation is ever
developed. Beyond that, due to being sed-based and due to its use of
heuristics, chainlint.sed has several limitations (such as being unable
to detect &&-chain breakage in subshells more than one level deep since
it only manually emulates recursion into a subshell).
Some of the comments in the chainlint self-tests unnecessarily reflect
the limitations of chainlint.sed even though those limitations are not
what is being tested. Therefore, simplify and generalize the comments to
explain only what is being tested, thus ensuring that they won't become
outdated if a more capable chainlint is ever developed.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The --chain-lint option uses heuristics and knowledge of shell syntax to
detect broken &&-chains in subshells by pure textual inspection. The
heuristics handle a range of stylistic variations in existing tests
(evolved over the years), however, they are still best-guesses. As such,
it is possible for future changes to accidentally break assumptions upon
which the heuristics are based. Protect against this possibility by
adding tests which check the linter itself for correctness.
In addition to protecting against regressions, these tests help document
(for humans) expected behavior, which is important since the linter's
implementation language ('sed') does not necessarily lend itself to easy
comprehension.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
