patch-id: fix stable patch id for binary / header-only

Patch-ids for binary patches are found by hashing the object
ids of the before and after objects in succession. However in
the --stable case, there is a bug where hunks are not flushed
for binary and header-only patch ids, which would always result
in a patch-id of 0000. The --unstable case is currently correct.

Reorder the logic to branch into 3 cases for populating the
patch body: header-only which populates nothing, binary which
populates the object ids, and normal which populates the text
diff. All branches will end up flushing the hunk.

Don't populate the ---a/ and +++b/ lines for binary diffs, to correspond
to those lines not being present in the "git diff" text output.
This is necessary because we advertise that the patch-id calculated
internally and used in format-patch is the same that what the
builtin "git patch-id" would produce when piped from a diff.

Update the test to run on both binary and normal files.

Signed-off-by: Jerry Zhang <jerry@skydio.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 24 insertions, 10 deletions

diff --git a/t/t3419-rebase-patch-id.sh b/t/t3419-rebase-patch-id.sh
index 295040f2fe3..d24e55aac8d 100755
--- a/t/t3419-rebase-patch-id.sh
+++ b/t/t3419-rebase-patch-id.sh
@@ -43,15 +43,16 @@ test_expect_success 'setup: 500 lines' '
 	git add newfile &&
 	git commit -q -m "add small file" &&
 
-	git cherry-pick main >/dev/null 2>&1
-'
+	git cherry-pick main >/dev/null 2>&1 &&
 
-test_expect_success 'setup attributes' '
-	echo "file binary" >.gitattributes
+	git branch -f squashed main &&
+	git checkout -q -f squashed &&
+	git reset -q --soft HEAD~2 &&
+	git commit -q -m squashed
 '
 
 test_expect_success 'detect upstream patch' '
-	git checkout -q main &&
+	git checkout -q main^{} &&
 	scramble file &&
 	git add file &&
 	git commit -q -m "change big file again" &&
@@ -61,14 +62,27 @@ test_expect_success 'detect upstream patch' '
 	test_must_be_empty revs
 '
 
+test_expect_success 'detect upstream patch binary' '
+	echo "file binary" >.gitattributes &&
+	git checkout -q other^{} &&
+	git rebase main &&
+	git rev-list main...HEAD~ >revs &&
+	test_must_be_empty revs &&
+	test_when_finished "rm .gitattributes"
+'
+
 test_expect_success 'do not drop patch' '
-	git branch -f squashed main &&
-	git checkout -q -f squashed &&
-	git reset -q --soft HEAD~2 &&
-	git commit -q -m squashed &&
 	git checkout -q other^{} &&
 	test_must_fail git rebase squashed &&
-	git rebase --quit
+	test_when_finished "git rebase --abort"
+'
+
+test_expect_success 'do not drop patch binary' '
+	echo "file binary" >.gitattributes &&
+	git checkout -q other^{} &&
+	test_must_fail git rebase squashed &&
+	test_when_finished "git rebase --abort" &&
+	test_when_finished "rm .gitattributes"
 '
 
 test_done