git-merge: honor pre-merge-commit hook

git-merge does not honor the pre-commit hook when doing automatic merge
commits, and for compatibility reasons this is going to stay.

Introduce a pre-merge-commit hook which is called for an automatic merge
commit just like pre-commit is called for a non-automatic merge commit
(or any other commit).

[js: * renamed hook from "pre-merge" to "pre-merge-commit"
     * only discard the index if the hook is actually present
     * expanded githooks documentation entry
     * clarified that hook should write messages to stderr
     * squashed test changes from the original series' patch 4/4
     * modified tests to follow new pattern from this series' patch 1/4
     * added a test case for non-executable merge hooks
     * added a test case for failed merges
     * when testing that the merge hook did not run, make sure we
       actually have a merge to perform (by resetting the "side" branch
       to its original state).
     * reworded commit message
]

Improved-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Michael J Gruber <git@grubix.eu>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 242 insertions, 0 deletions

diff --git a/t/t7503-pre-commit-and-pre-merge-commit-hooks.sh b/t/t7503-pre-commit-and-pre-merge-commit-hooks.sh
new file mode 100755
index 0000000000..7a5434c7ab
--- /dev/null
+++ b/t/t7503-pre-commit-and-pre-merge-commit-hooks.sh
@@ -0,0 +1,242 @@
+#!/bin/sh
+
+test_description='pre-commit and pre-merge-commit hooks'
+
+. ./test-lib.sh
+
+HOOKDIR="$(git rev-parse --git-dir)/hooks"
+PRECOMMIT="$HOOKDIR/pre-commit"
+PREMERGE="$HOOKDIR/pre-merge-commit"
+
+# Prepare sample scripts that write their $0 to actual_hooks
+test_expect_success 'sample script setup' '
+	mkdir -p "$HOOKDIR" &&
+	write_script "$HOOKDIR/success.sample" <<-\EOF &&
+	echo $0 >>actual_hooks
+	exit 0
+	EOF
+	write_script "$HOOKDIR/fail.sample" <<-\EOF &&
+	echo $0 >>actual_hooks
+	exit 1
+	EOF
+	write_script "$HOOKDIR/non-exec.sample" <<-\EOF &&
+	echo $0 >>actual_hooks
+	exit 1
+	EOF
+	chmod -x "$HOOKDIR/non-exec.sample" &&
+	write_script "$HOOKDIR/require-prefix.sample" <<-\EOF &&
+	echo $0 >>actual_hooks
+	test $GIT_PREFIX = "success/"
+	EOF
+	write_script "$HOOKDIR/check-author.sample" <<-\EOF
+	echo $0 >>actual_hooks
+	test "$GIT_AUTHOR_NAME" = "New Author" &&
+	test "$GIT_AUTHOR_EMAIL" = "newauthor@example.com"
+	EOF
+'
+
+test_expect_success 'root commit' '
+	echo "root" >file &&
+	git add file &&
+	git commit -m "zeroth" &&
+	git checkout -b side &&
+	echo "foo" >foo &&
+	git add foo &&
+	git commit -m "make it non-ff" &&
+	git branch side-orig side &&
+	git checkout master
+'
+
+test_expect_success 'setup conflicting branches' '
+	test_when_finished "git checkout master" &&
+	git checkout -b conflicting-a master &&
+	echo a >conflicting &&
+	git add conflicting &&
+	git commit -m conflicting-a &&
+	git checkout -b conflicting-b master &&
+	echo b >conflicting &&
+	git add conflicting &&
+	git commit -m conflicting-b
+'
+
+test_expect_success 'with no hook' '
+	test_when_finished "rm -f actual_hooks" &&
+	echo "foo" >file &&
+	git add file &&
+	git commit -m "first" &&
+	test_path_is_missing actual_hooks
+'
+
+test_expect_success 'with no hook (merge)' '
+	test_when_finished "rm -f actual_hooks" &&
+	git branch -f side side-orig &&
+	git checkout side &&
+	git merge -m "merge master" master &&
+	git checkout master &&
+	test_path_is_missing actual_hooks
+'
+
+test_expect_success '--no-verify with no hook' '
+	test_when_finished "rm -f actual_hooks" &&
+	echo "bar" >file &&
+	git add file &&
+	git commit --no-verify -m "bar" &&
+	test_path_is_missing actual_hooks
+'
+
+test_expect_success 'with succeeding hook' '
+	test_when_finished "rm -f \"$PRECOMMIT\" expected_hooks actual_hooks" &&
+	cp "$HOOKDIR/success.sample" "$PRECOMMIT" &&
+	echo "$PRECOMMIT" >expected_hooks &&
+	echo "more" >>file &&
+	git add file &&
+	git commit -m "more" &&
+	test_cmp expected_hooks actual_hooks
+'
+
+test_expect_success 'with succeeding hook (merge)' '
+	test_when_finished "rm -f \"$PREMERGE\" expected_hooks actual_hooks" &&
+	cp "$HOOKDIR/success.sample" "$PREMERGE" &&
+	echo "$PREMERGE" >expected_hooks &&
+	git checkout side &&
+	git merge -m "merge master" master &&
+	git checkout master &&
+	test_cmp expected_hooks actual_hooks
+'
+
+test_expect_success 'automatic merge fails; both hooks are available' '
+	test_when_finished "rm -f \"$PREMERGE\" \"$PRECOMMIT\"" &&
+	test_when_finished "rm -f expected_hooks actual_hooks" &&
+	test_when_finished "git checkout master" &&
+	cp "$HOOKDIR/success.sample" "$PREMERGE" &&
+	cp "$HOOKDIR/success.sample" "$PRECOMMIT" &&
+
+	git checkout conflicting-a &&
+	test_must_fail git merge -m "merge conflicting-b" conflicting-b &&
+	test_path_is_missing actual_hooks &&
+
+	echo "$PRECOMMIT" >expected_hooks &&
+	echo a+b >conflicting &&
+	git add conflicting &&
+	git commit -m "resolve conflict" &&
+	test_cmp expected_hooks actual_hooks
+'
+
+test_expect_success '--no-verify with succeeding hook' '
+	test_when_finished "rm -f \"$PRECOMMIT\" actual_hooks" &&
+	cp "$HOOKDIR/success.sample" "$PRECOMMIT" &&
+	echo "even more" >>file &&
+	git add file &&
+	git commit --no-verify -m "even more" &&
+	test_path_is_missing actual_hooks
+'
+
+test_expect_success 'with failing hook' '
+	test_when_finished "rm -f \"$PRECOMMIT\" expected_hooks actual_hooks" &&
+	cp "$HOOKDIR/fail.sample" "$PRECOMMIT" &&
+	echo "$PRECOMMIT" >expected_hooks &&
+	echo "another" >>file &&
+	git add file &&
+	test_must_fail git commit -m "another" &&
+	test_cmp expected_hooks actual_hooks
+'
+
+test_expect_success '--no-verify with failing hook' '
+	test_when_finished "rm -f \"$PRECOMMIT\" actual_hooks" &&
+	cp "$HOOKDIR/fail.sample" "$PRECOMMIT" &&
+	echo "stuff" >>file &&
+	git add file &&
+	git commit --no-verify -m "stuff" &&
+	test_path_is_missing actual_hooks
+'
+
+test_expect_success 'with failing hook (merge)' '
+	test_when_finished "rm -f \"$PREMERGE\" expected_hooks actual_hooks" &&
+	cp "$HOOKDIR/fail.sample" "$PREMERGE" &&
+	echo "$PREMERGE" >expected_hooks &&
+	git checkout side &&
+	test_must_fail git merge -m "merge master" master &&
+	git checkout master &&
+	test_cmp expected_hooks actual_hooks
+'
+
+test_expect_success POSIXPERM 'with non-executable hook' '
+	test_when_finished "rm -f \"$PRECOMMIT\" actual_hooks" &&
+	cp "$HOOKDIR/non-exec.sample" "$PRECOMMIT" &&
+	echo "content" >>file &&
+	git add file &&
+	git commit -m "content" &&
+	test_path_is_missing actual_hooks
+'
+
+test_expect_success POSIXPERM '--no-verify with non-executable hook' '
+	test_when_finished "rm -f \"$PRECOMMIT\" actual_hooks" &&
+	cp "$HOOKDIR/non-exec.sample" "$PRECOMMIT" &&
+	echo "more content" >>file &&
+	git add file &&
+	git commit --no-verify -m "more content" &&
+	test_path_is_missing actual_hooks
+'
+
+test_expect_success POSIXPERM 'with non-executable hook (merge)' '
+	test_when_finished "rm -f \"$PREMERGE\" actual_hooks" &&
+	cp "$HOOKDIR/non-exec.sample" "$PREMERGE" &&
+	git branch -f side side-orig &&
+	git checkout side &&
+	git merge -m "merge master" master &&
+	git checkout master &&
+	test_path_is_missing actual_hooks
+'
+
+test_expect_success 'with hook requiring GIT_PREFIX' '
+	test_when_finished "rm -rf \"$PRECOMMIT\" expected_hooks actual_hooks success" &&
+	cp "$HOOKDIR/require-prefix.sample" "$PRECOMMIT" &&
+	echo "$PRECOMMIT" >expected_hooks &&
+	echo "more content" >>file &&
+	git add file &&
+	mkdir success &&
+	(
+		cd success &&
+		git commit -m "hook requires GIT_PREFIX = success/"
+	) &&
+	test_cmp expected_hooks actual_hooks
+'
+
+test_expect_success 'with failing hook requiring GIT_PREFIX' '
+	test_when_finished "rm -rf \"$PRECOMMIT\" expected_hooks actual_hooks fail" &&
+	cp "$HOOKDIR/require-prefix.sample" "$PRECOMMIT" &&
+	echo "$PRECOMMIT" >expected_hooks &&
+	echo "more content" >>file &&
+	git add file &&
+	mkdir fail &&
+	(
+		cd fail &&
+		test_must_fail git commit -m "hook must fail"
+	) &&
+	git checkout -- file &&
+	test_cmp expected_hooks actual_hooks
+'
+
+test_expect_success 'check the author in hook' '
+	test_when_finished "rm -f \"$PRECOMMIT\" expected_hooks actual_hooks" &&
+	cp "$HOOKDIR/check-author.sample" "$PRECOMMIT" &&
+	cat >expected_hooks <<-EOF &&
+	$PRECOMMIT
+	$PRECOMMIT
+	$PRECOMMIT
+	EOF
+	test_must_fail git commit --allow-empty -m "by a.u.thor" &&
+	(
+		GIT_AUTHOR_NAME="New Author" &&
+		GIT_AUTHOR_EMAIL="newauthor@example.com" &&
+		export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL &&
+		git commit --allow-empty -m "by new.author via env" &&
+		git show -s
+	) &&
+	git commit --author="New Author <newauthor@example.com>" \
+		--allow-empty -m "by new.author via command line" &&
+	git show -s &&
+	test_cmp expected_hooks actual_hooks
+'
+
+test_done