On 10/03/2014 10:27 PM, Jeff King wrote:
> For small outputs, we sometimes use:
>
> test "$(some_cmd)" = "something we expect"
>
> instead of a full test_cmp. The downside of this is that
> when it fails, there is no output at all from the script.
> Let's introduce a small helper to make tests easier to
> debug.
>
> Signed-off-by: Jeff King <[email protected]>
> ---
> This is in the same boat as the last commit; we can drop it without
> hurting the rest of the series.
>
> Is test_eq too cutesy or obfuscated? I have often wanted it when
> debugging other tests, too. Our usual technique is to do:
>
> echo whatever >expect &&
> do_something >actual &&
> test_cmp expect actual
>
> That's a bit verbose. We could hide it behind something like test_eq,
> too, but it introduces several extra new processes. And I know people on
> some fork-challenged platforms are very sensitive to the number of
> spawned processes in the test suite.
I don't like the three-argument version of test_eq. Wouldn't using a
comparison operator other than "=" would be very confusing, given that
"eq" is in the name of the function? It also doesn't look like you use
this feature.
If you want to write a helper that allows arbitrary comparator
operators, then I think it would be more readable to put the comparison
operator in the middle, like
test_test foo = bar
And in fact once you've done that, couldn't we just make this a generic
wrapper for any `test` command?
test_test () {
if ! test "$@"
then
echo >&2 "test failed: $*"
false
fi
}
Feel free to bikeshed the function name.
An alternative direction to go would be to specialize the function for
equality testing and delegate to test_cmp to get better output for
failures, but optimized to avoid excess process creation in the happy path:
test_eq () {
if test "$1" != "$2"
then
printf "%s" "$1" >expect &&
printf "%s" "$2" >actual &&
test_cmp expect actual
fi
}
(but using properly-created temporary file names).
Finally, if we want a function intended mainly for checking program
output (like the test_eql function suggested by Junio), it might be
simpler to use if it accepts the function output on its stdin:
test_output () {
echo "$1" >expect &&
cat >actual &&
test_cmp expect actual
}
...
do_something | test_output whatever
This would make it easier to generate the input using an arbitrary shell
pipeline.
> [...]
Michael
--
Michael Haggerty
[email protected]
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