Re: [PATCH 4/5] tests: do not require Git to be built when testing an installed Git

[Jeff King <peff@peff.net>]

On Mon, Nov 12, 2018 at 05:48:37AM -0800, Johannes Schindelin via GitGitGadget wrote:

> diff --git a/t/test-lib.sh b/t/test-lib.sh
> index 832ede5099..1ea20dc2dc 100644
> --- a/t/test-lib.sh
> +++ b/t/test-lib.sh
> @@ -51,7 +51,7 @@ export LSAN_OPTIONS
>  
>  ################################################################
>  # It appears that people try to run tests without building...
> -"$GIT_BUILD_DIR/git" >/dev/null
> +test -n "$GIT_TEST_INSTALLED" || "$GIT_BUILD_DIR/git" >/dev/null ||
>  if test $? != 1
>  then
>  	echo >&2 'error: you do not seem to have built git yet.'

The original runs the command independently and then checks $?. Your
replacement chains the ||. I think it works, because the only case that
is different is if running git returns 0 (in which case we currently
complain, but the new code would quietly accept this).

That should never happen, but if it does we'd probably want to complain.
And it's pretty subtle all around.  Maybe this would be a bit clearer:

  if test -n "$GIT_TEST_INSTALLED"
  then
	: assume installed git is OK
  else
	"$GIT_BUILD_DIR/git" >/dev/null
	if test $? != 1
	then
		... die ...
	fi
  fi

Though arguably we should be checking that there is a git in our path in
the first instance. So maybe:

  if test -n "$GIT_TEST_INSTALLED"
	"$GIT_TEST_INSTALLED/git" >/dev/null
  else
	"$GIT_BUILD_DIR/git" >/dev/null
  fi
  if test $? != 1 ...

-Peff