Subject: [PATCH 13/20] userdiff tests + docs: document & test "diff.<driver>.x?funcname"

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Mon, 15 Feb 2021 01:52:29 +0100

Add the missing documentation for "diff.<driver>.funcname" and test
for how it and "diff.<driver>.xfuncname" interact.

Between the introduction of the "diff.<driver>.xfuncname" form in
45d9414fa5 (diff.*.xfuncname which uses "extended" regex's for hunk
header selection, 2008-09-18) and when this documentation was written
in 90b94c26f7 (Documentation: Add diff.<driver>.* to config,
2011-04-07) we forgot to document the existence of
"diff.<driver>.funcname".

Let's make a mention of it here, we could also partially revert the
former commit and discuss the more verbose form in gitattributes(5),
but let's stop short of that. It makes sense to guide users towards
ERE over BRE whenever possible.

Signed-off-by: Ævar Arnfjörð Bjarmason <[email-masked]>
---
 Documentation/config/diff.txt | 12 +++++++++++
 t/t4018/custom.sh             | 40 +++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/Documentation/config/diff.txt b/Documentation/config/diff.txt
index 2d3331f55c..5fce8021de 100644
--- a/Documentation/config/diff.txt
+++ b/Documentation/config/diff.txt
@@ -153,10 +153,22 @@ diff.<driver>.command::
 	The custom diff driver command.  See linkgit:gitattributes[5]
 	for details.
 
+diff.<driver>.funcname::
 diff.<driver>.xfuncname::
 	The regular expression that the diff driver should use to
 	recognize the hunk header.  A built-in pattern may also be used.
 	See linkgit:gitattributes[5] for details.
++
+When provided as `diff.<driver>.funcname` the regular expression is
+interpreted as a basic regular expression, with
+`diff.<driver>.xfuncname` it's interpreted as an extended regular
+expression.
++
+
+The `*.funcname` and `*.xfuncname` variables behave as if though they
+were one configuration variable for the purposes of what value
+eventually gets used. Setting `*.funcname` will override an earlier
+`*.xfuncname` and vice-versa.
 
 diff.<driver>.binary::
 	Set this option to true to make the diff driver treat files as
diff --git a/t/t4018/custom.sh b/t/t4018/custom.sh
index 20abb38451..b68d96a8af 100755
--- a/t/t4018/custom.sh
+++ b/t/t4018/custom.sh
@@ -78,6 +78,46 @@ public class Beer
 }
 EOF_TEST
 
+test_expect_success 'custom; setup config precedence' '
+	git config diff.custom.funcname "foo" &&
+	git config diff.custom.xfuncname "bar"
+'
+
+test_diff_funcname 'custom: config precedence' \
+	8<<\EOF_HUNK 9<<\EOF_TEST
+bar
+EOF_HUNK
+foo
+bar
+
+ChangeMe
+
+baz
+EOF_TEST
+
+test_expect_success 'custom: teardown' '
+	test_unconfig diff.custom.funcname &&
+	test_unconfig diff.custom.xfuncname
+'
+
+test_expect_success 'custom; setup config precedence' '
+	git config diff.custom.xfuncname "bar" &&
+	git config diff.custom.funcname "foo"
+
+'
+
+test_diff_funcname 'custom: config precedence' \
+	8<<\EOF_HUNK 9<<\EOF_TEST
+foo
+EOF_HUNK
+foo
+bar
+
+ChangeMe
+
+baz
+EOF_TEST
+
 test_expect_success 'custom: teardown' '
 	test_unconfig diff.custom.funcname &&
 	test_unconfig diff.custom.xfuncname
-- 
2.30.0.284.gd98b1dd5eaa7