ref-filter: consult want_color() before emitting colors

When color placeholders like %(color:red) are used in a
ref-filter format, we unconditionally output the colors,
even if the user has asked us for no colors. This usually
isn't a problem when the user is constructing a --format on
the command line, but it means we may do the wrong thing
when the format is fed from a script or alias. For example:

   $ git config alias.b 'branch --format=%(color:green)%(refname)'
   $ git b --no-color

should probably omit the green color. Likewise, running:

   $ git b >branches

should probably also omit the color, just as we would for
all baked-in coloring (and as we recently started to do for
user-specified colors in --pretty formats).

This commit makes both of those cases work by teaching
the ref-filter code to consult want_color() before
outputting any color. The color flag in ref_format defaults
to "-1", which means we'll consult color.ui, which in turn
defaults to the usual isatty() check on stdout. However,
callers like git-branch which support their own color config
(and command-line options) can override that.

The new tests independently cover all three of the callers
of ref-filter (for-each-ref, tag, and branch). Even though
these seem redundant, it confirms that we've correctly
plumbed through all of the necessary config to make colors
work by default.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 26 insertions, 11 deletions

diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index 7872a2f..2274a4b 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -7,6 +7,7 @@ test_description='for-each-ref test'
 
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-gpg.sh
+. "$TEST_DIRECTORY"/lib-terminal.sh
 
 # Mon Jul 3 23:18:43 2006 +0000
 datestamp=1151968723
@@ -412,19 +413,33 @@ test_expect_success 'Check for invalid refname format' '
 	test_must_fail git for-each-ref --format="%(refname:INVALID)"
 '
 
-cat >expected <<EOF
-$(git rev-parse --short refs/heads/master) <GREEN>master<RESET>
-$(git rev-parse --short refs/remotes/origin/master) <GREEN>origin/master<RESET>
-$(git rev-parse --short refs/tags/testtag) <GREEN>testtag<RESET>
-$(git rev-parse --short refs/tags/two) <GREEN>two<RESET>
-EOF
+test_expect_success 'set up color tests' '
+	cat >expected.color <<-EOF &&
+	$(git rev-parse --short refs/heads/master) <GREEN>master<RESET>
+	$(git rev-parse --short refs/remotes/origin/master) <GREEN>origin/master<RESET>
+	$(git rev-parse --short refs/tags/testtag) <GREEN>testtag<RESET>
+	$(git rev-parse --short refs/tags/two) <GREEN>two<RESET>
+	EOF
+	sed "s/<[^>]*>//g" <expected.color >expected.bare &&
+	color_format="%(objectname:short) %(color:green)%(refname:short)"
+'
 
-test_expect_success 'Check %(color:...) ' '
-	git for-each-ref \
-		--format="%(objectname:short) %(color:green)%(refname:short)" \
-		>actual.raw &&
+test_expect_success TTY '%(color) shows color with a tty' '
+	test_terminal env TERM=vt100 \
+		git for-each-ref --format="$color_format" >actual.raw &&
 	test_decode_color <actual.raw >actual &&
-	test_cmp expected actual
+	test_cmp expected.color actual
+'
+
+test_expect_success '%(color) does not show color without tty' '
+	TERM=vt100 git for-each-ref --format="$color_format" >actual &&
+	test_cmp expected.bare actual
+'
+
+test_expect_success 'color.ui=always can override tty check' '
+	git -c color.ui=always for-each-ref --format="$color_format" >actual.raw &&
+	test_decode_color <actual.raw >actual &&
+	test_cmp expected.color actual
 '
 
 cat >expected <<\EOF