Re: [PATCH v2 04/29] log: add exhaustive tests for pattern style options & config

> +	echo 2e >expect &&
> +	# In PCRE \d in [\d] is like saying "0-9", and matches the 2
> +	# in 2e...
> +	git -C num_commits log -1 --pretty="tformat:%s" -F -E --perl-regexp --grep="[\d]" >actual &&
> +	test_cmp expect actual &&
> +	echo 1d >expect &&
> +	# ...in POSIX basic & extended it is the same as [d],
> +	# i.e. "d", which matches 1d, but not and does not match 2e.

> +	git -C num_commits log -1 --pretty="tformat:%s" -F -E --grep="[\d]" >actual &&
>  	test_cmp expect actual
>  '
>  
> @@ -280,6 +301,77 @@ test_expect_success 'log with grep.patternType configuration and command line' '
>  	test_cmp expect actual
>  '
>  
> +test_expect_success 'log with various grep.patternType configurations & command-lines' '
> +	git init pattern-type &&
> +	(
> +		cd pattern-type &&
> +		test_commit 1 file A &&
> +
> +		# The tagname is overridden here because creating a
> +		# tag called "(1|2)" as test_commit would otherwise
> +		# implicitly do would fail on e.g. MINGW.

> +		# POSIX extended needs to have | escaped to match it
> +		# literally, whereas under basic this is the same as
> +		# (|2), i.e. it would also match "1". This test checks
> +		# for extended by asserting that it is not matching
> +		# what basic would match.
> +		git -c grep.patternType=extended log --pretty=tformat:%s \
> +			--grep="\|2" >actual.extended &&

> +		if test_have_prereq PCRE
> +		then
> +			# Only PCRE would match [\d]\| with only
> +			# "(1|2)" due to [\d]. POSIX basic would match
> +			# both it and "1", and POSIX extended would
> +			# match neither.