git notes merge: Add automatic conflict resolvers (ours, theirs, union)

The new -s/--strategy command-line option to 'git notes merge' allow the user
to choose how notes merge conflicts should be resolved. There are four valid
strategies to choose from:

1. "manual" (the default): This will let the user manually resolve conflicts.
   This option currently fails with an error message. It will be implemented
   properly in future patches.

2. "ours": This automatically chooses the local version of a conflict, and
   discards the remote version.

3. "theirs": This automatically chooses the remote version of a conflict, and
   discards the local version.

4. "union": This automatically resolves the conflict by appending the remote
   version to the local version.

The strategies are implemented using the combine_notes_* functions from the
notes.h API.

The patch also includes testcases verifying the correct implementation of
these strategies.

This patch has been improved by the following contributions:
- Jonathan Nieder: Future-proof by always checking add_note() return value
- Stephen Boyd: Use test_commit
- Stephen Boyd: Use correct option name

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

1 files changed, 502 insertions, 0 deletions

diff --git a/t/t3309-notes-merge-auto-resolve.sh b/t/t3309-notes-merge-auto-resolve.sh
new file mode 100755
index 0000000000..1a1fc7edd3
--- /dev/null
+++ b/t/t3309-notes-merge-auto-resolve.sh
@@ -0,0 +1,502 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Johan Herland
+#
+
+test_description='Test notes merging with auto-resolving strategies'
+
+. ./test-lib.sh
+
+# Set up a notes merge scenario with all kinds of potential conflicts
+test_expect_success 'setup commits' '
+	test_commit 1st &&
+	test_commit 2nd &&
+	test_commit 3rd &&
+	test_commit 4th &&
+	test_commit 5th &&
+	test_commit 6th &&
+	test_commit 7th &&
+	test_commit 8th &&
+	test_commit 9th &&
+	test_commit 10th &&
+	test_commit 11th &&
+	test_commit 12th &&
+	test_commit 13th &&
+	test_commit 14th &&
+	test_commit 15th
+'
+
+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=$(git rev-parse 5th^{commit})
+commit_sha6=$(git rev-parse 6th^{commit})
+commit_sha7=$(git rev-parse 7th^{commit})
+commit_sha8=$(git rev-parse 8th^{commit})
+commit_sha9=$(git rev-parse 9th^{commit})
+commit_sha10=$(git rev-parse 10th^{commit})
+commit_sha11=$(git rev-parse 11th^{commit})
+commit_sha12=$(git rev-parse 12th^{commit})
+commit_sha13=$(git rev-parse 13th^{commit})
+commit_sha14=$(git rev-parse 14th^{commit})
+commit_sha15=$(git rev-parse 15th^{commit})
+
+verify_notes () {
+	notes_ref="$1"
+	suffix="$2"
+	git -c core.notesRef="refs/notes/$notes_ref" notes |
+		sort >"output_notes_$suffix" &&
+	test_cmp "expect_notes_$suffix" "output_notes_$suffix" &&
+	git -c core.notesRef="refs/notes/$notes_ref" log --format="%H %s%n%N" \
+		>"output_log_$suffix" &&
+	test_cmp "expect_log_$suffix" "output_log_$suffix"
+}
+
+test_expect_success 'setup merge base (x)' '
+	git config core.notesRef refs/notes/x &&
+	git notes add -m "x notes on 6th commit" 6th &&
+	git notes add -m "x notes on 7th commit" 7th &&
+	git notes add -m "x notes on 8th commit" 8th &&
+	git notes add -m "x notes on 9th commit" 9th &&
+	git notes add -m "x notes on 10th commit" 10th &&
+	git notes add -m "x notes on 11th commit" 11th &&
+	git notes add -m "x notes on 12th commit" 12th &&
+	git notes add -m "x notes on 13th commit" 13th &&
+	git notes add -m "x notes on 14th commit" 14th &&
+	git notes add -m "x notes on 15th commit" 15th
+'
+
+cat <<EOF | sort >expect_notes_x
+457a85d6c814ea208550f15fcc48f804ac8dc023 $commit_sha15
+b0c95b954301d69da2bc3723f4cb1680d355937c $commit_sha14
+5d30216a129eeffa97d9694ffe8c74317a560315 $commit_sha13
+dd161bc149470fd890dd4ab52a4cbd79bbd18c36 $commit_sha12
+7abbc45126d680336fb24294f013a7cdfa3ed545 $commit_sha11
+b8d03e173f67f6505a76f6e00cf93440200dd9be $commit_sha10
+20c613c835011c48a5abe29170a2402ca6354910 $commit_sha9
+a3daf8a1e4e5dc3409a303ad8481d57bfea7f5d6 $commit_sha8
+897003322b53bc6ca098e9324ee508362347e734 $commit_sha7
+11d97fdebfa5ceee540a3da07bce6fa0222bc082 $commit_sha6
+EOF
+
+cat >expect_log_x <<EOF
+$commit_sha15 15th
+x notes on 15th commit
+
+$commit_sha14 14th
+x notes on 14th commit
+
+$commit_sha13 13th
+x notes on 13th commit
+
+$commit_sha12 12th
+x notes on 12th commit
+
+$commit_sha11 11th
+x notes on 11th commit
+
+$commit_sha10 10th
+x notes on 10th commit
+
+$commit_sha9 9th
+x notes on 9th commit
+
+$commit_sha8 8th
+x notes on 8th commit
+
+$commit_sha7 7th
+x notes on 7th commit
+
+$commit_sha6 6th
+x notes on 6th commit
+
+$commit_sha5 5th
+
+$commit_sha4 4th
+
+$commit_sha3 3rd
+
+$commit_sha2 2nd
+
+$commit_sha1 1st
+
+EOF
+
+test_expect_success 'verify state of merge base (x)' 'verify_notes x x'
+
+test_expect_success 'setup local branch (y)' '
+	git update-ref refs/notes/y refs/notes/x &&
+	git config core.notesRef refs/notes/y &&
+	git notes add -f -m "y notes on 3rd commit" 3rd &&
+	git notes add -f -m "y notes on 4th commit" 4th &&
+	git notes add -f -m "y notes on 5th commit" 5th &&
+	git notes remove 6th &&
+	git notes remove 7th &&
+	git notes remove 8th &&
+	git notes add -f -m "y notes on 12th commit" 12th &&
+	git notes add -f -m "y notes on 13th commit" 13th &&
+	git notes add -f -m "y notes on 14th commit" 14th &&
+	git notes add -f -m "y notes on 15th commit" 15th
+'
+
+cat <<EOF | sort >expect_notes_y
+68b8630d25516028bed862719855b3d6768d7833 $commit_sha15
+5de7ea7ad4f47e7ff91989fb82234634730f75df $commit_sha14
+3a631fdb6f41b05b55d8f4baf20728ba8f6fccbc $commit_sha13
+a66055fa82f7a03fe0c02a6aba3287a85abf7c62 $commit_sha12
+7abbc45126d680336fb24294f013a7cdfa3ed545 $commit_sha11
+b8d03e173f67f6505a76f6e00cf93440200dd9be $commit_sha10
+20c613c835011c48a5abe29170a2402ca6354910 $commit_sha9
+154508c7a0bcad82b6fe4b472bc4c26b3bf0825b $commit_sha5
+e2bfd06a37dd2031684a59a6e2b033e212239c78 $commit_sha4
+5772f42408c0dd6f097a7ca2d24de0e78d1c46b1 $commit_sha3
+EOF
+
+cat >expect_log_y <<EOF
+$commit_sha15 15th
+y notes on 15th commit
+
+$commit_sha14 14th
+y notes on 14th commit
+
+$commit_sha13 13th
+y notes on 13th commit
+
+$commit_sha12 12th
+y notes on 12th commit
+
+$commit_sha11 11th
+x notes on 11th commit
+
+$commit_sha10 10th
+x notes on 10th commit
+
+$commit_sha9 9th
+x notes on 9th commit
+
+$commit_sha8 8th
+
+$commit_sha7 7th
+
+$commit_sha6 6th
+
+$commit_sha5 5th
+y notes on 5th commit
+
+$commit_sha4 4th
+y notes on 4th commit
+
+$commit_sha3 3rd
+y notes on 3rd commit
+
+$commit_sha2 2nd
+
+$commit_sha1 1st
+
+EOF
+
+test_expect_success 'verify state of local branch (y)' 'verify_notes y y'
+
+test_expect_success 'setup remote branch (z)' '
+	git update-ref refs/notes/z refs/notes/x &&
+	git config core.notesRef refs/notes/z &&
+	git notes add -f -m "z notes on 2nd commit" 2nd &&
+	git notes add -f -m "y notes on 4th commit" 4th &&
+	git notes add -f -m "z notes on 5th commit" 5th &&
+	git notes remove 6th &&
+	git notes add -f -m "z notes on 8th commit" 8th &&
+	git notes remove 9th &&
+	git notes add -f -m "z notes on 11th commit" 11th &&
+	git notes remove 12th &&
+	git notes add -f -m "y notes on 14th commit" 14th &&
+	git notes add -f -m "z notes on 15th commit" 15th
+'
+
+cat <<EOF | sort >expect_notes_z
+9b4b2c61f0615412da3c10f98ff85b57c04ec765 $commit_sha15
+5de7ea7ad4f47e7ff91989fb82234634730f75df $commit_sha14
+5d30216a129eeffa97d9694ffe8c74317a560315 $commit_sha13
+7e3c53503a3db8dd996cb62e37c66e070b44b54d $commit_sha11
+b8d03e173f67f6505a76f6e00cf93440200dd9be $commit_sha10
+851e1638784a884c7dd26c5d41f3340f6387413a $commit_sha8
+897003322b53bc6ca098e9324ee508362347e734 $commit_sha7
+99fc34adfc400b95c67b013115e37e31aa9a6d23 $commit_sha5
+e2bfd06a37dd2031684a59a6e2b033e212239c78 $commit_sha4
+283b48219aee9a4105f6cab337e789065c82c2b9 $commit_sha2
+EOF
+
+cat >expect_log_z <<EOF
+$commit_sha15 15th
+z notes on 15th commit
+
+$commit_sha14 14th
+y notes on 14th commit
+
+$commit_sha13 13th
+x notes on 13th commit
+
+$commit_sha12 12th
+
+$commit_sha11 11th
+z notes on 11th commit
+
+$commit_sha10 10th
+x notes on 10th commit
+
+$commit_sha9 9th
+
+$commit_sha8 8th
+z notes on 8th commit
+
+$commit_sha7 7th
+x notes on 7th commit
+
+$commit_sha6 6th
+
+$commit_sha5 5th
+z notes on 5th commit
+
+$commit_sha4 4th
+y notes on 4th commit
+
+$commit_sha3 3rd
+
+$commit_sha2 2nd
+z notes on 2nd commit
+
+$commit_sha1 1st
+
+EOF
+
+test_expect_success 'verify state of remote branch (z)' 'verify_notes z z'
+
+# At this point, before merging z into y, we have the following status:
+#
+# commit | base/x  | local/y | remote/z | diff from x to y/z         | result
+# -------|---------|---------|----------|----------------------------|-------
+# 1st    | [none]  | [none]  | [none]   | unchanged / unchanged      | [none]
+# 2nd    | [none]  | [none]  | 283b482  | unchanged / added          | 283b482
+# 3rd    | [none]  | 5772f42 | [none]   | added     / unchanged      | 5772f42
+# 4th    | [none]  | e2bfd06 | e2bfd06  | added     / added (same)   | e2bfd06
+# 5th    | [none]  | 154508c | 99fc34a  | added     / added (diff)   | ???
+# 6th    | 11d97fd | [none]  | [none]   | removed   / removed        | [none]
+# 7th    | 8970033 | [none]  | 8970033  | removed   / unchanged      | [none]
+# 8th    | a3daf8a | [none]  | 851e163  | removed   / changed        | ???
+# 9th    | 20c613c | 20c613c | [none]   | unchanged / removed        | [none]
+# 10th   | b8d03e1 | b8d03e1 | b8d03e1  | unchanged / unchanged      | b8d03e1
+# 11th   | 7abbc45 | 7abbc45 | 7e3c535  | unchanged / changed        | 7e3c535
+# 12th   | dd161bc | a66055f | [none]   | changed   / removed        | ???
+# 13th   | 5d30216 | 3a631fd | 5d30216  | changed   / unchanged      | 3a631fd
+# 14th   | b0c95b9 | 5de7ea7 | 5de7ea7  | changed   / changed (same) | 5de7ea7
+# 15th   | 457a85d | 68b8630 | 9b4b2c6  | changed   / changed (diff) | ???
+
+test_expect_success 'merge z into y with invalid strategy => Fail/No changes' '
+	git config core.notesRef refs/notes/y &&
+	test_must_fail git notes merge --strategy=foo z &&
+	# Verify no changes (y)
+	verify_notes y y
+'
+
+cat <<EOF | sort >expect_notes_ours
+68b8630d25516028bed862719855b3d6768d7833 $commit_sha15
+5de7ea7ad4f47e7ff91989fb82234634730f75df $commit_sha14
+3a631fdb6f41b05b55d8f4baf20728ba8f6fccbc $commit_sha13
+a66055fa82f7a03fe0c02a6aba3287a85abf7c62 $commit_sha12
+7e3c53503a3db8dd996cb62e37c66e070b44b54d $commit_sha11
+b8d03e173f67f6505a76f6e00cf93440200dd9be $commit_sha10
+154508c7a0bcad82b6fe4b472bc4c26b3bf0825b $commit_sha5
+e2bfd06a37dd2031684a59a6e2b033e212239c78 $commit_sha4
+5772f42408c0dd6f097a7ca2d24de0e78d1c46b1 $commit_sha3
+283b48219aee9a4105f6cab337e789065c82c2b9 $commit_sha2
+EOF
+
+cat >expect_log_ours <<EOF
+$commit_sha15 15th
+y notes on 15th commit
+
+$commit_sha14 14th
+y notes on 14th commit
+
+$commit_sha13 13th
+y notes on 13th commit
+
+$commit_sha12 12th
+y notes on 12th commit
+
+$commit_sha11 11th
+z notes on 11th commit
+
+$commit_sha10 10th
+x notes on 10th commit
+
+$commit_sha9 9th
+
+$commit_sha8 8th
+
+$commit_sha7 7th
+
+$commit_sha6 6th
+
+$commit_sha5 5th
+y notes on 5th commit
+
+$commit_sha4 4th
+y notes on 4th commit
+
+$commit_sha3 3rd
+y notes on 3rd commit
+
+$commit_sha2 2nd
+z notes on 2nd commit
+
+$commit_sha1 1st
+
+EOF
+
+test_expect_success 'merge z into y with "ours" strategy => Non-conflicting 3-way merge' '
+	git notes merge --strategy=ours z &&
+	verify_notes y ours
+'
+
+test_expect_success 'reset to pre-merge state (y)' '
+	git update-ref refs/notes/y refs/notes/y^1 &&
+	# Verify pre-merge state
+	verify_notes y y
+'
+
+cat <<EOF | sort >expect_notes_theirs
+9b4b2c61f0615412da3c10f98ff85b57c04ec765 $commit_sha15
+5de7ea7ad4f47e7ff91989fb82234634730f75df $commit_sha14
+3a631fdb6f41b05b55d8f4baf20728ba8f6fccbc $commit_sha13
+7e3c53503a3db8dd996cb62e37c66e070b44b54d $commit_sha11
+b8d03e173f67f6505a76f6e00cf93440200dd9be $commit_sha10
+851e1638784a884c7dd26c5d41f3340f6387413a $commit_sha8
+99fc34adfc400b95c67b013115e37e31aa9a6d23 $commit_sha5
+e2bfd06a37dd2031684a59a6e2b033e212239c78 $commit_sha4
+5772f42408c0dd6f097a7ca2d24de0e78d1c46b1 $commit_sha3
+283b48219aee9a4105f6cab337e789065c82c2b9 $commit_sha2
+EOF
+
+cat >expect_log_theirs <<EOF
+$commit_sha15 15th
+z notes on 15th commit
+
+$commit_sha14 14th
+y notes on 14th commit
+
+$commit_sha13 13th
+y notes on 13th commit
+
+$commit_sha12 12th
+
+$commit_sha11 11th
+z notes on 11th commit
+
+$commit_sha10 10th
+x notes on 10th commit
+
+$commit_sha9 9th
+
+$commit_sha8 8th
+z notes on 8th commit
+
+$commit_sha7 7th
+
+$commit_sha6 6th
+
+$commit_sha5 5th
+z notes on 5th commit
+
+$commit_sha4 4th
+y notes on 4th commit
+
+$commit_sha3 3rd
+y notes on 3rd commit
+
+$commit_sha2 2nd
+z notes on 2nd commit
+
+$commit_sha1 1st
+
+EOF
+
+test_expect_success 'merge z into y with "theirs" strategy => Non-conflicting 3-way merge' '
+	git notes merge --strategy=theirs z &&
+	verify_notes y theirs
+'
+
+test_expect_success 'reset to pre-merge state (y)' '
+	git update-ref refs/notes/y refs/notes/y^1 &&
+	# Verify pre-merge state
+	verify_notes y y
+'
+
+cat <<EOF | sort >expect_notes_union
+7c4e546efd0fe939f876beb262ece02797880b54 $commit_sha15
+5de7ea7ad4f47e7ff91989fb82234634730f75df $commit_sha14
+3a631fdb6f41b05b55d8f4baf20728ba8f6fccbc $commit_sha13
+a66055fa82f7a03fe0c02a6aba3287a85abf7c62 $commit_sha12
+7e3c53503a3db8dd996cb62e37c66e070b44b54d $commit_sha11
+b8d03e173f67f6505a76f6e00cf93440200dd9be $commit_sha10
+851e1638784a884c7dd26c5d41f3340f6387413a $commit_sha8
+6c841cc36ea496027290967ca96bd2bef54dbb47 $commit_sha5
+e2bfd06a37dd2031684a59a6e2b033e212239c78 $commit_sha4
+5772f42408c0dd6f097a7ca2d24de0e78d1c46b1 $commit_sha3
+283b48219aee9a4105f6cab337e789065c82c2b9 $commit_sha2
+EOF
+
+cat >expect_log_union <<EOF
+$commit_sha15 15th
+y notes on 15th commit
+
+z notes on 15th commit
+
+$commit_sha14 14th
+y notes on 14th commit
+
+$commit_sha13 13th
+y notes on 13th commit
+
+$commit_sha12 12th
+y notes on 12th commit
+
+$commit_sha11 11th
+z notes on 11th commit
+
+$commit_sha10 10th
+x notes on 10th commit
+
+$commit_sha9 9th
+
+$commit_sha8 8th
+z notes on 8th commit
+
+$commit_sha7 7th
+
+$commit_sha6 6th
+
+$commit_sha5 5th
+y notes on 5th commit
+
+z notes on 5th commit
+
+$commit_sha4 4th
+y notes on 4th commit
+
+$commit_sha3 3rd
+y notes on 3rd commit
+
+$commit_sha2 2nd
+z notes on 2nd commit
+
+$commit_sha1 1st
+
+EOF
+
+test_expect_success 'merge z into y with "union" strategy => Non-conflicting 3-way merge' '
+	git notes merge --strategy=union z &&
+	verify_notes y union
+'
+
+test_done