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[PATCH v5 3/4] git-merge: honor pre-merge-commit hook

From
Josh Steadmon <steadmon@google.com>
Date
Aug 7, 2019, 18:57 UTC
Message-ID
<2d41e0ff79045a3a0abf83d8f580e958023fb331.1565203880.git.steadmon@google.com>
In-Reply-To
<cover.1565203880.git.steadmon@google.com>
From: Michael J Gruber <git@drmicha.warpmail.net>

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>
---
 Documentation/githooks.txt                    | 21 +++++
 builtin/merge.c                               | 12 +++
 ...-pre-commit-and-pre-merge-commit-hooks.sh} | 84 ++++++++++++++++++-
 templates/hooks--pre-merge-commit.sample      | 13 +++
 4 files changed, 129 insertions(+), 1 deletion(-)
 rename t/{t7503-pre-commit-hook.sh => t7503-pre-commit-and-pre-merge-commit-hooks.sh} (63%)
 create mode 100755 templates/hooks--pre-merge-commit.sample
diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
index 82cd573776..d9da474fb0 100644
--- a/Documentation/githooks.txt
+++ b/Documentation/githooks.txt
@@ -103,6 +103,27 @@ The default 'pre-commit' hook, when enabled--and with the
 `hooks.allownonascii` config option unset or set to false--prevents
 the use of non-ASCII filenames.
 
+pre-merge-commit
+~~~~~~~~~~~~~~~~
+
+This hook is invoked by linkgit:git-merge[1]. It takes no parameters, and is
+invoked after the merge has been carried out successfully and before
+obtaining the proposed commit log message to
+make a commit.  Exiting with a non-zero status from this script
+causes the `git merge` command to abort before creating a commit.
+
+The default 'pre-merge-commit' hook, when enabled, runs the
+'pre-commit' hook, if the latter is enabled.
+
+This hook is invoked with the environment variable
+`GIT_EDITOR=:` if the command will not bring up an editor
+to modify the commit message.
+
+If the merge cannot be carried out automatically, the conflicts
+need to be resolved and the result committed separately (see
+linkgit:git-merge[1]). At that point, this hook will not be executed,
+but the 'pre-commit' hook will, if it is enabled.
+
 prepare-commit-msg
 ~~~~~~~~~~~~~~~~~~
 
diff --git a/builtin/merge.c b/builtin/merge.c
index 4425a7a12e..bf0ae68c40 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -816,6 +816,18 @@ static void write_merge_heads(struct commit_list *);
 static void prepare_to_commit(struct commit_list *remoteheads)
 {
 	struct strbuf msg = STRBUF_INIT;
+	const char *index_file = get_index_file();
+
+	if (run_commit_hook(0 < option_edit, index_file, "pre-merge-commit", NULL))
+		abort_commit(remoteheads, NULL);
+	/*
+	 * Re-read the index as pre-merge-commit hook could have updated it,
+	 * and write it out as a tree.  We must do this before we invoke
+	 * the editor and after we invoke run_status above.
+	 */
+	if (find_hook("pre-merge-commit"))
+		discard_cache();
+	read_cache_from(index_file);
 	strbuf_addbuf(&msg, &merge_msg);
 	if (squash)
 		BUG("the control must not reach here under --squash");
diff --git a/t/t7503-pre-commit-hook.sh b/t/t7503-pre-commit-and-pre-merge-commit-hooks.sh
similarity index 63%
rename from t/t7503-pre-commit-hook.sh
rename to t/t7503-pre-commit-and-pre-merge-commit-hooks.sh
index 6aa83204c2..7a5434c7ab 100755
--- a/t/t7503-pre-commit-hook.sh
+++ b/t/t7503-pre-commit-and-pre-merge-commit-hooks.sh
@@ -1,11 +1,12 @@
 #!/bin/sh
 
-test_description='pre-commit hook'
+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' '
@@ -34,6 +35,30 @@ test_expect_success 'sample script setup' '
 	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 &&
@@ -42,6 +67,15 @@ test_expect_success 'with no hook' '
 	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 &&
@@ -60,6 +94,34 @@ test_expect_success 'with succeeding hook' '
 	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" &&
@@ -88,6 +150,16 @@ test_expect_success '--no-verify with failing hook' '
 	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" &&
@@ -106,6 +178,16 @@ test_expect_success POSIXPERM '--no-verify with non-executable hook' '
 	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" &&
diff --git a/templates/hooks--pre-merge-commit.sample b/templates/hooks--pre-merge-commit.sample
new file mode 100755
index 0000000000..399eab1924
--- /dev/null
+++ b/templates/hooks--pre-merge-commit.sample
@@ -0,0 +1,13 @@
+#!/bin/sh
+#
+# An example hook script to verify what is about to be committed.
+# Called by "git merge" with no arguments.  The hook should
+# exit with non-zero status after issuing an appropriate message to
+# stderr if it wants to stop the merge commit.
+#
+# To enable this hook, rename this file to "pre-merge-commit".
+
+. git-sh-setup
+test -x "$GIT_DIR/hooks/pre-commit" &&
+        exec "$GIT_DIR/hooks/pre-commit"
+:

-- 
2.22.0.770.g0f2c4a37fd-goog
Previous: Josh SteadmonNext: Josh Steadmon
Message 57 of 59 in “pre-merge hook”
  1. 0/4 pre-merge hookMichael J Gruber, Sep 22, 2017
  2. 2/4 merge: do no-verify like commitMichael J Gruber, Sep 22, 2017
  3. Stefan BellerSep 22, 2017
  4. 1/4 git-merge: Honor pre-merge hookMichael J Gruber, Sep 22, 2017
  5. Stefan BellerSep 22, 2017
  6. Martin ÅgrenSep 23, 2017
  7. 3/4 merge: --no-verify to bypass pre-merge hookMichael J Gruber, Sep 22, 2017
  8. Junio C HamanoSep 23, 2017
  9. Michael J GruberSep 25, 2017
  10. 4/4 t7503: add tests for pre-merge-hookMichael J Gruber, Sep 22, 2017
  11. Stefan BellerSep 22, 2017
  12. Junio C HamanoOct 2, 2017
  13. Stefan BellerOct 2, 2017
  14. Junio C HamanoOct 17, 2017
  15. 0/4 pre-merge hookJosh Steadmon, Jul 18, 2019
  16. 0/4 pre-merge hookJosh Steadmon, Jul 18, 2019
  17. 1/4 git-merge: Honor pre-merge hookJosh Steadmon, Jul 18, 2019
  18. Martin ÅgrenJul 29, 2019
  19. 2/4 merge: do no-verify like commitJosh Steadmon, Jul 18, 2019
  20. 3/4 merge: --no-verify to bypass pre-merge hookJosh Steadmon, Jul 18, 2019
  21. Martin ÅgrenJul 29, 2019
  22. Josh SteadmonJul 29, 2019
  23. 4/4 t7503: add tests for pre-merge-hookJosh Steadmon, Jul 18, 2019
  24. Martin ÅgrenJul 29, 2019
  25. Josh SteadmonJul 29, 2019
  26. Martin ÅgrenJul 30, 2019
  27. Josh SteadmonJul 31, 2019
  28. Martin ÅgrenJul 29, 2019
  29. Josh SteadmonJul 29, 2019
  30. Martin ÅgrenJul 29, 2019
  31. Josh SteadmonJul 29, 2019
  32. 0/4 pre-merge-commit hookJosh Steadmon, Aug 1, 2019
  33. 1/4 t7503: verify proper hook executionJosh Steadmon, Aug 1, 2019
  34. Martin ÅgrenAug 2, 2019
  35. 2/4 merge: do no-verify like commitJosh Steadmon, Aug 1, 2019
  36. 3/4 git-merge: honor pre-merge-commit hookJosh Steadmon, Aug 1, 2019
  37. Martin ÅgrenAug 2, 2019
  38. Josh SteadmonAug 2, 2019
  39. 4/4 merge: --no-verify to bypass pre-merge-commit hookJosh Steadmon, Aug 1, 2019
  40. Martin ÅgrenAug 2, 2019
  41. 1/5 t7503: use "&&" in "test_when_finished" rather than ";"Martin Ågren, Aug 2, 2019
  42. 2/5 t7503: avoid touch when mtime doesn't matterMartin Ågren, Aug 2, 2019
  43. 5/5 t7503: test failing merge with both hooks availableMartin Ågren, Aug 2, 2019
  44. 4/5 t7503: don't create "actual_hooks" for later appendingMartin Ågren, Aug 2, 2019
  45. 3/5 t7503: simplify file-jugglingMartin Ågren, Aug 2, 2019
  46. Josh SteadmonAug 2, 2019
  47. 0/4 pre-merge-commit hookJosh Steadmon, Aug 5, 2019
  48. 1/4 t7503: verify proper hook executionJosh Steadmon, Aug 5, 2019
  49. Junio C HamanoAug 6, 2019
  50. Josh SteadmonAug 7, 2019
  51. 2/4 merge: do no-verify like commitJosh Steadmon, Aug 5, 2019
  52. 3/4 git-merge: honor pre-merge-commit hookJosh Steadmon, Aug 5, 2019
  53. 4/4 merge: --no-verify to bypass pre-merge-commit hookJosh Steadmon, Aug 5, 2019
  54. 0/4 pre-merge-commit hookJosh Steadmon, Aug 7, 2019
  55. 1/4 t7503: verify proper hook executionJosh Steadmon, Aug 7, 2019
  56. 2/4 merge: do no-verify like commitJosh Steadmon, Aug 7, 2019
  57. 3/4 git-merge: honor pre-merge-commit hookJosh Steadmon, Aug 7, 2019
  58. 4/4 merge: --no-verify to bypass pre-merge-commit hookJosh Steadmon, Aug 7, 2019
  59. Martin ÅgrenAug 8, 2019

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