git notes merge: Initial implementation handling trivial merges only

This initial implementation of 'git notes merge' only handles the trivial
merge cases (i.e. where the merge is either a no-op, or a fast-forward).

The patch includes testcases for these trivial merge cases.

Future patches will extend the functionality of 'git notes merge'.

This patch has been improved by the following contributions:
- Stephen Boyd: Simplify argc logic
- Stephen Boyd: Use test_commit
- Ævar Arnfjörð Bjarmason: Don't use C99 comments.
- Jonathan Nieder: Add constants for common verbosity values
- Jonathan Nieder: Use trace_printf(...) instead of OUTPUT(o, 5, ...)
- Jonathan Nieder: Remove extraneous show() function
- Jonathan Nieder: Clarify handling of empty/missing notes ref in notes_merge()
- Junio C Hamano: fixup minor style issues

Thanks-to: Stephen Boyd <bebarino@gmail.com>
Thanks-to: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Thanks-to: Jonathan Nieder <jrnieder@gmail.com>
Thanks-to: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 180 insertions, 0 deletions

diff --git a/t/t3308-notes-merge.sh b/t/t3308-notes-merge.sh
new file mode 100755
index 0000000..9acb684
--- /dev/null
+++ b/t/t3308-notes-merge.sh
@@ -0,0 +1,180 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Johan Herland
+#
+
+test_description='Test merging of notes trees'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	test_commit 1st &&
+	test_commit 2nd &&
+	test_commit 3rd &&
+	test_commit 4th &&
+	test_commit 5th &&
+	# Create notes on 4 first commits
+	git config core.notesRef refs/notes/x &&
+	git notes add -m "Notes on 1st commit" 1st &&
+	git notes add -m "Notes on 2nd commit" 2nd &&
+	git notes add -m "Notes on 3rd commit" 3rd &&
+	git notes add -m "Notes on 4th commit" 4th
+'
+
+commit_sha1=$(git rev-parse 1st^{commit})
+commit_sha2=$(git rev-parse 2nd^{commit})
+commit_sha3=$(git rev-parse 3rd^{commit})
+commit_sha4=$(git rev-parse 4th^{commit})
+commit_sha5=$(git rev-parse 5th^{commit})
+
+verify_notes () {
+	notes_ref="$1"
+	git -c core.notesRef="refs/notes/$notes_ref" notes |
+		sort >"output_notes_$notes_ref" &&
+	test_cmp "expect_notes_$notes_ref" "output_notes_$notes_ref" &&
+	git -c core.notesRef="refs/notes/$notes_ref" log --format="%H %s%n%N" \
+		>"output_log_$notes_ref" &&
+	test_cmp "expect_log_$notes_ref" "output_log_$notes_ref"
+}
+
+cat <<EOF | sort >expect_notes_x
+5e93d24084d32e1cb61f7070505b9d2530cca987 $commit_sha4
+8366731eeee53787d2bdf8fc1eff7d94757e8da0 $commit_sha3
+eede89064cd42441590d6afec6c37b321ada3389 $commit_sha2
+daa55ffad6cb99bf64226532147ffcaf5ce8bdd1 $commit_sha1
+EOF
+
+cat >expect_log_x <<EOF
+$commit_sha5 5th
+
+$commit_sha4 4th
+Notes on 4th commit
+
+$commit_sha3 3rd
+Notes on 3rd commit
+
+$commit_sha2 2nd
+Notes on 2nd commit
+
+$commit_sha1 1st
+Notes on 1st commit
+
+EOF
+
+test_expect_success 'verify initial notes (x)' '
+	verify_notes x
+'
+
+cp expect_notes_x expect_notes_y
+cp expect_log_x expect_log_y
+
+test_expect_success 'fail to merge empty notes ref into empty notes ref (z => y)' '
+	test_must_fail git -c "core.notesRef=refs/notes/y" notes merge z
+'
+
+test_expect_success 'fail to merge into various non-notes refs' '
+	test_must_fail git -c "core.notesRef=refs/notes" notes merge x &&
+	test_must_fail git -c "core.notesRef=refs/notes/" notes merge x &&
+	mkdir -p .git/refs/notes/dir &&
+	test_must_fail git -c "core.notesRef=refs/notes/dir" notes merge x &&
+	test_must_fail git -c "core.notesRef=refs/notes/dir/" notes merge x &&
+	test_must_fail git -c "core.notesRef=refs/heads/master" notes merge x &&
+	test_must_fail git -c "core.notesRef=refs/notes/y:" notes merge x &&
+	test_must_fail git -c "core.notesRef=refs/notes/y:foo" notes merge x &&
+	test_must_fail git -c "core.notesRef=refs/notes/foo^{bar" notes merge x
+'
+
+test_expect_success 'fail to merge various non-note-trees' '
+	git config core.notesRef refs/notes/y &&
+	test_must_fail git notes merge refs/notes &&
+	test_must_fail git notes merge refs/notes/ &&
+	test_must_fail git notes merge refs/notes/dir &&
+	test_must_fail git notes merge refs/notes/dir/ &&
+	test_must_fail git notes merge refs/heads/master &&
+	test_must_fail git notes merge x: &&
+	test_must_fail git notes merge x:foo &&
+	test_must_fail git notes merge foo^{bar
+'
+
+test_expect_success 'merge notes into empty notes ref (x => y)' '
+	git config core.notesRef refs/notes/y &&
+	git notes merge x &&
+	verify_notes y &&
+	# x and y should point to the same notes commit
+	test "$(git rev-parse refs/notes/x)" = "$(git rev-parse refs/notes/y)"
+'
+
+test_expect_success 'merge empty notes ref (z => y)' '
+	git notes merge z &&
+	# y should not change (still == x)
+	test "$(git rev-parse refs/notes/x)" = "$(git rev-parse refs/notes/y)"
+'
+
+test_expect_success 'change notes on other notes ref (y)' '
+	# Not touching notes to 1st commit
+	git notes remove 2nd &&
+	git notes append -m "More notes on 3rd commit" 3rd &&
+	git notes add -f -m "New notes on 4th commit" 4th &&
+	git notes add -m "Notes on 5th commit" 5th
+'
+
+test_expect_success 'merge previous notes commit (y^ => y) => No-op' '
+	pre_state="$(git rev-parse refs/notes/y)" &&
+	git notes merge y^ &&
+	# y should not move
+	test "$pre_state" = "$(git rev-parse refs/notes/y)"
+'
+
+cat <<EOF | sort >expect_notes_y
+0f2efbd00262f2fd41dfae33df8765618eeacd99 $commit_sha5
+dec2502dac3ea161543f71930044deff93fa945c $commit_sha4
+4069cdb399fd45463ec6eef8e051a16a03592d91 $commit_sha3
+daa55ffad6cb99bf64226532147ffcaf5ce8bdd1 $commit_sha1
+EOF
+
+cat >expect_log_y <<EOF
+$commit_sha5 5th
+Notes on 5th commit
+
+$commit_sha4 4th
+New notes on 4th commit
+
+$commit_sha3 3rd
+Notes on 3rd commit
+
+More notes on 3rd commit
+
+$commit_sha2 2nd
+
+$commit_sha1 1st
+Notes on 1st commit
+
+EOF
+
+test_expect_success 'verify changed notes on other notes ref (y)' '
+	verify_notes y
+'
+
+test_expect_success 'verify unchanged notes on original notes ref (x)' '
+	verify_notes x
+'
+
+test_expect_success 'merge original notes (x) into changed notes (y) => No-op' '
+	git notes merge -vvv x &&
+	verify_notes y &&
+	verify_notes x
+'
+
+cp expect_notes_y expect_notes_x
+cp expect_log_y expect_log_x
+
+test_expect_success 'merge changed (y) into original (x) => Fast-forward' '
+	git config core.notesRef refs/notes/x &&
+	git notes merge y &&
+	verify_notes x &&
+	verify_notes y &&
+	# x and y should point to same the notes commit
+	test "$(git rev-parse refs/notes/x)" = "$(git rev-parse refs/notes/y)"
+'
+
+test_done