merge-file: add an option to process object IDs

git merge-file knows how to merge files on the file system already.  It
would be helpful, however, to allow it to also merge single blobs.
Teach it an `--object-id` option which means that its arguments are
object IDs and not files to allow it to do so.

We handle the empty blob specially since read_mmblob doesn't read it
directly and otherwise users cannot specify an empty ancestor.

Signed-off-by: brian m. carlson <bk2204@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/t/t6403-merge-file.sh b/t/t6403-merge-file.sh
index 1a7082323d..2c92209eca 100755
--- a/t/t6403-merge-file.sh
+++ b/t/t6403-merge-file.sh
@@ -65,11 +65,30 @@ test_expect_success 'merge with no changes' '
 	test_cmp test.txt orig.txt
 '
 
+test_expect_success 'merge with no changes with --object-id' '
+	git add orig.txt &&
+	git merge-file -p --object-id :orig.txt :orig.txt :orig.txt >actual &&
+	test_cmp actual orig.txt
+'
+
 test_expect_success "merge without conflict" '
 	cp new1.txt test.txt &&
 	git merge-file test.txt orig.txt new2.txt
 '
 
+test_expect_success 'merge without conflict with --object-id' '
+	git add orig.txt new2.txt &&
+	git merge-file --object-id :orig.txt :orig.txt :new2.txt >actual &&
+	git rev-parse :new2.txt >expected &&
+	test_cmp actual expected
+'
+
+test_expect_success 'can accept object ID with --object-id' '
+	git merge-file --object-id $(test_oid empty_blob) $(test_oid empty_blob) :new2.txt >actual &&
+	git rev-parse :new2.txt >expected &&
+	test_cmp actual expected
+'
+
 test_expect_success 'works in subdirectory' '
 	mkdir dir &&
 	cp new1.txt dir/a.txt &&
@@ -138,6 +157,31 @@ test_expect_success "expected conflict markers" '
 	test_cmp expect.txt test.txt
 '
 
+test_expect_success "merge with conflicts with --object-id" '
+	git add backup.txt orig.txt new3.txt &&
+	test_must_fail git merge-file -p --object-id :backup.txt :orig.txt :new3.txt >actual &&
+	sed -e "s/<< test.txt/<< :backup.txt/" \
+	    -e "s/>> new3.txt/>> :new3.txt/" \
+	    expect.txt >expect &&
+	test_cmp expect actual &&
+	test_must_fail git merge-file --object-id :backup.txt :orig.txt :new3.txt >oid &&
+	git cat-file blob "$(cat oid)" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success "merge with conflicts with --object-id with labels" '
+	git add backup.txt orig.txt new3.txt &&
+	test_must_fail git merge-file -p --object-id \
+		-L test.txt -L orig.txt -L new3.txt \
+		:backup.txt :orig.txt :new3.txt >actual &&
+	test_cmp expect.txt actual &&
+	test_must_fail git merge-file --object-id \
+		-L test.txt -L orig.txt -L new3.txt \
+		:backup.txt :orig.txt :new3.txt >oid &&
+	git cat-file blob "$(cat oid)" >actual &&
+	test_cmp expect.txt actual
+'
+
 test_expect_success "merge conflicting with --ours" '
 	cp backup.txt test.txt &&
 
@@ -256,6 +300,14 @@ test_expect_success 'binary files cannot be merged' '
 	grep "Cannot merge binary files" merge.err
 '
 
+test_expect_success 'binary files cannot be merged with --object-id' '
+	cp "$TEST_DIRECTORY"/test-binary-1.png . &&
+	git add orig.txt new1.txt test-binary-1.png &&
+	test_must_fail git merge-file --object-id \
+		:orig.txt :test-binary-1.png :new1.txt 2> merge.err &&
+	grep "Cannot merge binary files" merge.err
+'
+
 test_expect_success 'MERGE_ZEALOUS simplifies non-conflicts' '
 	sed -e "s/deerit.\$/deerit;/" -e "s/me;\$/me./" <new5.txt >new6.txt &&
 	sed -e "s/deerit.\$/deerit,/" -e "s/me;\$/me,/" <new5.txt >new7.txt &&
@@ -389,4 +441,10 @@ test_expect_success 'conflict sections match existing line endings' '
 	test $(tr "\015" Q <nolf.txt | grep "^[<=>].*Q$" | wc -l) = 0
 '
 
+test_expect_success '--object-id fails without repository' '
+	empty="$(test_oid empty_blob)" &&
+	nongit test_must_fail git merge-file --object-id $empty $empty $empty 2>err &&
+	grep "not a git repository" err
+'
+
 test_done