git/t/t7504-commit-msg-hook.sh
Elijah Newren eddd1a411d merge-recursive: enforce rule that index matches head before merging
builtin/merge.c says that when we are about to perform a merge:

    ...the index must be in sync with the head commit.  The strategies are
    responsible to ensure this.

merge-recursive has always relied on unpack_trees() to enforce this
requirement, except in the case of an "Already up to date!" merge.
unpack-trees.c does not actually enforce this requirement, though.  It
allows for a pair of exceptions, in cases which it refers to as #14(ALT)
and #2ALT.  Documentation/technical/trivial-merge.txt can be consulted for
the precise meanings of the various case numbers and their meanings for
unpack-trees.c, but we have a high-level description of the intent behind
these two exceptions in a combined and summarized form in
Documentation/git-merge.txt:

    ...[merge will] abort if there are any changes registered in the index
    relative to the `HEAD` commit.  (One exception is when the changed index
    entries are in the state that would result from the merge already.)

While this high-level description does describe conditions under which it
would be safe to allow the index to diverge from HEAD, it does not match
what is actually implemented.  In particular, unpack-trees.c has no
knowledge of renames, and these two exceptions were written assuming that
no renames take place.  Once renames get into the mix, it is no longer
safe to allow the index to not match for #2ALT.  We could modify
unpack-trees to only allow #14(ALT) as an exception, but that would be
more strict than required for the resolve strategy (since the resolve
strategy doesn't handle renames at all).  Therefore, unpack_trees.c seems
like the wrong place to fix this.

Further, if someone fixes the combination of break and rename detection
and modifies merge-recursive to take advantage of the combination, then it
will also no longer be safe to allow the index to not match for #14(ALT)
when the recursive strategy is in use.  Therefore, leaving one of the
exceptions in place with the recursive merge strategy feels like we are
just leaving a latent bug in the code for folks in the future to stumble
across.

It may be possible to fix both unpack-trees and merge-recursive in a way
that implements the exception as stated in Documentation/git-merge.txt,
but it would be somewhat complex, possibly also buggy at first, and
ultimately, not all that valuable.  Instead, just enforce the requirement
stated in builtin/merge.c; error out if the index does not match the HEAD
commit, just like the 'ours' and 'octopus' strategies do.

Some testcase fixups were in order:
  t7611: had many tests designed to show that `git merge --abort` could
	 not always restore the index and working tree to the state they
	 were in before the merge started.  The tests that were associated
	 with having changes in the index before the merge started are no
         longer applicable, so they have been removed.
  t7504: had a few tests that had stray staged changes that were not
         actually part of the test under consideration
  t6044: We no longer expect stray staged changes to sometimes result
         in the merge continuing.  Also, fix a case where a merge
         didn't abort but should have.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-11 09:38:36 -07:00

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#!/bin/sh
test_description='commit-msg hook'
. ./test-lib.sh
test_expect_success 'with no hook' '
echo "foo" > file &&
git add file &&
git commit -m "first"
'
# set up fake editor for interactive editing
cat > fake-editor <<'EOF'
#!/bin/sh
cp FAKE_MSG "$1"
exit 0
EOF
chmod +x fake-editor
## Not using test_set_editor here so we can easily ensure the editor variable
## is only set for the editor tests
FAKE_EDITOR="$(pwd)/fake-editor"
export FAKE_EDITOR
test_expect_success 'with no hook (editor)' '
echo "more foo" >> file &&
git add file &&
echo "more foo" > FAKE_MSG &&
GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit
'
test_expect_success '--no-verify with no hook' '
echo "bar" > file &&
git add file &&
git commit --no-verify -m "bar"
'
test_expect_success '--no-verify with no hook (editor)' '
echo "more bar" > file &&
git add file &&
echo "more bar" > FAKE_MSG &&
GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit --no-verify
'
# now install hook that always succeeds
HOOKDIR="$(git rev-parse --git-dir)/hooks"
HOOK="$HOOKDIR/commit-msg"
mkdir -p "$HOOKDIR"
cat > "$HOOK" <<EOF
#!/bin/sh
exit 0
EOF
chmod +x "$HOOK"
test_expect_success 'with succeeding hook' '
echo "more" >> file &&
git add file &&
git commit -m "more"
'
test_expect_success 'with succeeding hook (editor)' '
echo "more more" >> file &&
git add file &&
echo "more more" > FAKE_MSG &&
GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit
'
test_expect_success '--no-verify with succeeding hook' '
echo "even more" >> file &&
git add file &&
git commit --no-verify -m "even more"
'
test_expect_success '--no-verify with succeeding hook (editor)' '
echo "even more more" >> file &&
git add file &&
echo "even more more" > FAKE_MSG &&
GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit --no-verify
'
# now a hook that fails
cat > "$HOOK" <<EOF
#!/bin/sh
exit 1
EOF
commit_msg_is () {
test "$(git log --pretty=format:%s%b -1)" = "$1"
}
test_expect_success 'with failing hook' '
echo "another" >> file &&
git add file &&
test_must_fail git commit -m "another"
'
test_expect_success 'with failing hook (editor)' '
echo "more another" >> file &&
git add file &&
echo "more another" > FAKE_MSG &&
! (GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit)
'
test_expect_success '--no-verify with failing hook' '
echo "stuff" >> file &&
git add file &&
git commit --no-verify -m "stuff"
'
test_expect_success '--no-verify with failing hook (editor)' '
echo "more stuff" >> file &&
git add file &&
echo "more stuff" > FAKE_MSG &&
GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit --no-verify
'
test_expect_success 'merge fails with failing hook' '
test_when_finished "git branch -D newbranch" &&
test_when_finished "git checkout -f master" &&
git checkout --orphan newbranch &&
: >file2 &&
git add file2 &&
git commit --no-verify file2 -m in-side-branch &&
test_must_fail git merge --allow-unrelated-histories master &&
commit_msg_is "in-side-branch" # HEAD before merge
'
test_expect_success 'merge bypasses failing hook with --no-verify' '
test_when_finished "git branch -D newbranch" &&
test_when_finished "git checkout -f master" &&
git checkout --orphan newbranch &&
git rm -f file &&
: >file2 &&
git add file2 &&
git commit --no-verify file2 -m in-side-branch &&
git merge --no-verify --allow-unrelated-histories master &&
commit_msg_is "Merge branch '\''master'\'' into newbranch"
'
chmod -x "$HOOK"
test_expect_success POSIXPERM 'with non-executable hook' '
echo "content" >file &&
git add file &&
git commit -m "content"
'
test_expect_success POSIXPERM 'with non-executable hook (editor)' '
echo "content again" >> file &&
git add file &&
echo "content again" > FAKE_MSG &&
GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit -m "content again"
'
test_expect_success POSIXPERM '--no-verify with non-executable hook' '
echo "more content" >> file &&
git add file &&
git commit --no-verify -m "more content"
'
test_expect_success POSIXPERM '--no-verify with non-executable hook (editor)' '
echo "even more content" >> file &&
git add file &&
echo "even more content" > FAKE_MSG &&
GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit --no-verify
'
# now a hook that edits the commit message
cat > "$HOOK" <<'EOF'
#!/bin/sh
echo "new message" > "$1"
exit 0
EOF
chmod +x "$HOOK"
test_expect_success 'hook edits commit message' '
echo "additional" >> file &&
git add file &&
git commit -m "additional" &&
commit_msg_is "new message"
'
test_expect_success 'hook edits commit message (editor)' '
echo "additional content" >> file &&
git add file &&
echo "additional content" > FAKE_MSG &&
GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit &&
commit_msg_is "new message"
'
test_expect_success "hook doesn't edit commit message" '
echo "plus" >> file &&
git add file &&
git commit --no-verify -m "plus" &&
commit_msg_is "plus"
'
test_expect_success "hook doesn't edit commit message (editor)" '
echo "more plus" >> file &&
git add file &&
echo "more plus" > FAKE_MSG &&
GIT_EDITOR="\"\$FAKE_EDITOR\"" git commit --no-verify &&
commit_msg_is "more plus"
'
test_expect_success 'hook called in git-merge picks up commit message' '
test_when_finished "git branch -D newbranch" &&
test_when_finished "git checkout -f master" &&
git checkout --orphan newbranch &&
git rm -f file &&
: >file2 &&
git add file2 &&
git commit --no-verify file2 -m in-side-branch &&
git merge --allow-unrelated-histories master &&
commit_msg_is "new message"
'
test_expect_failure 'merge --continue remembers --no-verify' '
test_when_finished "git branch -D newbranch" &&
test_when_finished "git checkout -f master" &&
git checkout master &&
echo a >file2 &&
git add file2 &&
git commit --no-verify -m "add file2 to master" &&
git checkout -b newbranch master^ &&
echo b >file2 &&
git add file2 &&
git commit --no-verify file2 -m in-side-branch &&
git merge --no-verify -m not-rewritten-by-hook master &&
# resolve conflict:
echo c >file2 &&
git add file2 &&
git merge --continue &&
commit_msg_is not-rewritten-by-hook
'
# set up fake editor to replace `pick` by `reword`
cat > reword-editor <<'EOF'
#!/bin/sh
mv "$1" "$1".bup &&
sed 's/^pick/reword/' <"$1".bup >"$1"
EOF
chmod +x reword-editor
REWORD_EDITOR="$(pwd)/reword-editor"
export REWORD_EDITOR
test_expect_success 'hook is called for reword during `rebase -i`' '
GIT_SEQUENCE_EDITOR="\"$REWORD_EDITOR\"" git rebase -i HEAD^ &&
commit_msg_is "new message"
'
test_done