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>

diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
index 82cd573776cec696774c467979c6da10f23554c3..d9da474fb01c2e7fb10118b38d17205c5231cfc9 100644 (file)
--- 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 4425a7a12e92b40df27e75f04ac02b63df43d95a..bf0ae68c40caca9124ae756e191d9a62b314cb56 100644 (file)
--- 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 6aa83204c25350572c34f362dfcb3c164303c63b..7a5434c7ab8580d93816cf531c4ea16f0da96c64 100755 (executable)
--- 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 (executable)
index 0000000..399eab1
--- /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"
+: