diff --stat: tests for long filenames and big change counts

In preparation for updates to the "diff --stat" that updates the logic
to split the allotted columns into the name part and the graph part to
make the output more readable, add a handful of tests to document the
corner case behaviour in which long filenames and big changes are shown.

When a pathname is so long that it cannot fit on the column, the current
code truncates it to make sure that the graph part has enough room to show
a meaningful graph.  If the actual change is small (e.g. only one line
changed), this results in the final output that is shorter than the width
we aim for.

Signed-off-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4052-stat-output.sh

@@ -0,0 +1,182 @@
+#!/bin/sh
+#
+# Copyright (c) 2012 Zbigniew Jędrzejewski-Szmek
+#
+
+test_description='test --stat output of various commands'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-terminal.sh
+
+# 120 character name
+name=aaaaaaaaaa
+name=$name$name$name$name$name$name$name$name$name$name$name$name
+test_expect_success 'preparation' '
+	>"$name" &&
+	git add "$name" &&
+	git commit -m message &&
+	echo a >"$name" &&
+	git commit -m message "$name"
+'
+
+while read cmd args
+do
+	cat >expect <<-'EOF'
+	 ...aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa |    1 +
+	EOF
+	test_expect_success "$cmd: a short graph bar does not extend to the full width" '
+		git $cmd $args >output &&
+		grep " | " output >actual &&
+		test_cmp expect actual
+	'
+
+	cat >expect <<-'EOF'
+	 ...aaaaaaaaaaaaaaaaaaaaaa |    1 +
+	EOF
+	test_expect_success "$cmd --stat=width: name is chopped to leave room to the right of a short bar" '
+		git $cmd $args --stat=40 >output &&
+		grep " | " output >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "$cmd --stat-width=width with long name" '
+		git $cmd $args --stat-width=40 >output &&
+		grep " | " output >actual &&
+		test_cmp expect actual
+	'
+
+	cat >expect <<-'EOF'
+	 ...aaaaaaaaaaaaaaaaaaaaaaaaaaa |    1 +
+	EOF
+	test_expect_success "$cmd --stat=...,name-width with long name" '
+		git $cmd $args --stat=60,30 >output &&
+		grep " | " output >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "$cmd --stat-name-width with long name" '
+		git $cmd $args --stat-name-width=30 >output &&
+		grep " | " output >actual &&
+		test_cmp expect actual
+	'
+done <<\EOF
+format-patch -1 --stdout
+diff HEAD^ HEAD --stat
+show --stat
+log -1 --stat
+EOF
+
+
+test_expect_success 'preparation for big change tests' '
+	>abcd &&
+	git add abcd &&
+	git commit -m message &&
+	i=0 &&
+	while test $i -lt 1000
+	do
+		echo $i && i=$(($i + 1))
+	done >abcd &&
+	git commit -m message abcd
+'
+
+cat >expect80 <<'EOF'
+ abcd | 1000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+EOF
+
+while read verb expect cmd args
+do
+	test_expect_success "$cmd $verb COLUMNS (big change)" '
+		COLUMNS=200 git $cmd $args >output
+		grep " | " output >actual &&
+		test_cmp "$expect" actual
+	'
+done <<\EOF
+ignores expect80 format-patch -1 --stdout
+ignores expect80 diff HEAD^ HEAD --stat
+ignores expect80 show --stat
+ignores expect80 log -1 --stat
+EOF
+
+cat >expect <<'EOF'
+ abcd | 1000 ++++++++++++++++++++++++++
+EOF
+while read cmd args
+do
+	test_expect_success "$cmd --stat=width with big change" '
+		git $cmd $args --stat=40 >output
+		grep " | " output >actual &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "$cmd --stat-width=width with big change" '
+		git $cmd $args --stat-width=40 >output
+		grep " | " output >actual &&
+		test_cmp expect actual
+	'
+done <<\EOF
+format-patch -1 --stdout
+diff HEAD^ HEAD --stat
+show --stat
+log -1 --stat
+EOF
+
+test_expect_success 'preparation for long filename tests' '
+	cp abcd aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa &&
+	git add aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa &&
+	git commit -m message
+'
+
+cat >expect <<'EOF'
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa | 1000 +++++
+EOF
+while read cmd args
+do
+	test_expect_success "$cmd --stat=width with big change and long name favors name part" '
+		git $cmd $args --stat-width=60 >output &&
+		grep " | " output >actual &&
+		test_cmp expect actual
+	'
+done <<\EOF
+format-patch -1 --stdout
+diff HEAD^ HEAD --stat
+show --stat
+log -1 --stat
+EOF
+
+cat >expect80 <<'EOF'
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa | 1000 ++++++++++++++++++++
+EOF
+while read verb expect cmd args
+do
+	test_expect_success "$cmd $verb COLUMNS (long filename)" '
+		COLUMNS=200 git $cmd $args >output
+		grep " | " output >actual &&
+		test_cmp "$expect" actual
+	'
+done <<\EOF
+ignores expect80 format-patch -1 --stdout
+ignores expect80 diff HEAD^ HEAD --stat
+ignores expect80 show --stat
+ignores expect80 log -1 --stat
+EOF
+
+cat >expect <<'EOF'
+ abcd | 1000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+EOF
+test_expect_success 'merge --stat ignores COLUMNS (big change)' '
+	git checkout -b branch HEAD^^ &&
+	COLUMNS=100 git merge --stat --no-ff master^ >output &&
+	grep " | " output >actual
+	test_cmp expect actual
+'
+
+cat >expect <<'EOF'
+ ...aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa | 1000 ++++++++++++++++++++
+EOF
+test_expect_success 'merge --stat ignores COLUMNS (long filename)' '
+	COLUMNS=100 git merge --stat --no-ff master >output &&
+	grep " | " output >actual
+	test_cmp expect actual
+'
+
+test_done