t7006: add tests for how git tag paginates

Using, e.g., `git -c pager.tag tag -a new-tag` results in errors such as
"Vim: Warning: Output is not to a terminal" and a garbled terminal.
Someone who makes use of both `git tag -a` and `git tag -l` will
probably not set `pager.tag`, so that `git tag -a` will actually work,
at the cost of not paging output of `git tag -l`.

Since we're about to change how `git tag` respects `pager.tag`, add tests
around this, including how the configuration is ignored if --no-pager or
--paginate are used.

Construct tests with a few different subcommands. First, use -l. Second,
use "no arguments" and --contains, since those imply -l. (There are
more arguments which imply -l, but using these two should be enough.)

Third, use -a as a representative for "not -l". Actually, the tests use
`git tag -am` so no editor is launched, but that is irrelevant, since we
just want to see whether the pager is used or not. Make one of the tests
demonstrate the broken behavior mentioned above, where `git tag -a`
respects `pager.tag`.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7006-pager.sh

@@ -134,6 +134,73 @@ test_expect_success TTY 'configuration can enable pager (from subdir)' '
 	}
 '
 
+test_expect_success TTY 'git tag -l defaults to not paging' '
+	rm -f paginated.out &&
+	test_terminal git tag -l &&
+	! test -e paginated.out
+'
+
+test_expect_success TTY 'git tag -l respects pager.tag' '
+	rm -f paginated.out &&
+	test_terminal git -c pager.tag tag -l &&
+	test -e paginated.out
+'
+
+test_expect_success TTY 'git tag -l respects --no-pager' '
+	rm -f paginated.out &&
+	test_terminal git -c pager.tag --no-pager tag -l &&
+	! test -e paginated.out
+'
+
+test_expect_success TTY 'git tag with no args defaults to not paging' '
+	# no args implies -l so this should page like -l
+	rm -f paginated.out &&
+	test_terminal git tag &&
+	! test -e paginated.out
+'
+
+test_expect_success TTY 'git tag with no args respects pager.tag' '
+	# no args implies -l so this should page like -l
+	rm -f paginated.out &&
+	test_terminal git -c pager.tag tag &&
+	test -e paginated.out
+'
+
+test_expect_success TTY 'git tag --contains defaults to not paging' '
+	# --contains implies -l so this should page like -l
+	rm -f paginated.out &&
+	test_terminal git tag --contains &&
+	! test -e paginated.out
+'
+
+test_expect_success TTY 'git tag --contains respects pager.tag' '
+	# --contains implies -l so this should page like -l
+	rm -f paginated.out &&
+	test_terminal git -c pager.tag tag --contains &&
+	test -e paginated.out
+'
+
+test_expect_success TTY 'git tag -a defaults to not paging' '
+	test_when_finished "git tag -d newtag" &&
+	rm -f paginated.out &&
+	test_terminal git tag -am message newtag &&
+	! test -e paginated.out
+'
+
+test_expect_failure TTY 'git tag -a ignores pager.tag' '
+	test_when_finished "git tag -d newtag" &&
+	rm -f paginated.out &&
+	test_terminal git -c pager.tag tag -am message newtag &&
+	! test -e paginated.out
+'
+
+test_expect_success TTY 'git tag -a respects --paginate' '
+	test_when_finished "git tag -d newtag" &&
+	rm -f paginated.out &&
+	test_terminal git --paginate tag -am message newtag &&
+	test -e paginated.out
+'
+
 # A colored commit log will begin with an appropriate ANSI escape
 # for the first color; the text "commit" comes later.
 colorful() {