patch: show copy information for identical copies

When showing copy information because we are duplicating contents,
for example, when performing a `diff --find-copies-harder -M100 -B100`,
then show copy from/to lines in a patch, and do not show context.
Ensure that we can also parse such patches.

1 files changed, 47 insertions, 10 deletions

diff --git a/tests/diff/diff_helpers.c b/tests/diff/diff_helpers.c
index 8fa8e3eb5..50752b203 100644
--- a/tests/diff/diff_helpers.c
+++ b/tests/diff/diff_helpers.c
@@ -242,18 +242,44 @@ void diff_print_raw(FILE *fp, git_diff *diff)
 			git_diff_print_callback__to_file_handle, fp ? fp : stderr));
 }
 
+static size_t num_modified_deltas(git_diff *diff)
+{
+	const git_diff_delta *delta;
+	size_t i, cnt = 0;
+
+	for (i = 0; i < git_diff_num_deltas(diff); i++) {
+		delta = git_diff_get_delta(diff, i);
+
+		if (delta->status != GIT_DELTA_UNMODIFIED)
+			cnt++;
+	}
+
+	return cnt;
+}
+
 void diff_assert_equal(git_diff *a, git_diff *b)
 {
 	const git_diff_delta *ad, *bd;
-	size_t i;
+	size_t i, j;
 
 	assert(a && b);
 
-	cl_assert_equal_i(git_diff_num_deltas(a), git_diff_num_deltas(b));
+	cl_assert_equal_i(num_modified_deltas(a), num_modified_deltas(b));
+
+	for (i = 0, j = 0;
+		i < git_diff_num_deltas(a) && j < git_diff_num_deltas(b); ) {
 
-	for (i = 0; i < git_diff_num_deltas(a); i++) {
 		ad = git_diff_get_delta(a, i);
-		bd = git_diff_get_delta(b, i);
+		bd = git_diff_get_delta(b, j);
+
+		if (ad->status == GIT_DELTA_UNMODIFIED) {
+			i++;
+			continue;
+		}
+		if (bd->status == GIT_DELTA_UNMODIFIED) {
+			j++;
+			continue;
+		}
 
 		cl_assert_equal_i(ad->status, bd->status);
 		cl_assert_equal_i(ad->flags, bd->flags);
@@ -265,15 +291,26 @@ void diff_assert_equal(git_diff *a, git_diff *b)
 		 * computed deltas will have flags of `VALID_ID` and
 		 * `EXISTS` (parsed deltas will not query the ODB.)
 		 */
-		cl_assert_equal_oid(&ad->old_file.id, &bd->old_file.id);
-		cl_assert_equal_i(ad->old_file.id_abbrev, bd->old_file.id_abbrev);
+
+		/* an empty id indicates that it wasn't presented, because
+		 * the diff was identical.  (eg, pure rename, mode change only, etc)
+		 */
+		if (ad->old_file.id_abbrev && bd->old_file.id_abbrev) {
+			cl_assert_equal_i(ad->old_file.id_abbrev, bd->old_file.id_abbrev);
+			cl_assert_equal_oid(&ad->old_file.id, &bd->old_file.id);
+			cl_assert_equal_i(ad->old_file.mode, bd->old_file.mode);
+		}
 		cl_assert_equal_s(ad->old_file.path, bd->old_file.path);
-		cl_assert_equal_i(ad->old_file.mode, bd->old_file.mode);
 
-		cl_assert_equal_oid(&ad->new_file.id, &bd->new_file.id);
-		cl_assert_equal_i(ad->new_file.id_abbrev, bd->new_file.id_abbrev);
+		if (ad->new_file.id_abbrev && bd->new_file.id_abbrev) {
+			cl_assert_equal_oid(&ad->new_file.id, &bd->new_file.id);
+			cl_assert_equal_i(ad->new_file.id_abbrev, bd->new_file.id_abbrev);
+			cl_assert_equal_i(ad->new_file.mode, bd->new_file.mode);
+		}
 		cl_assert_equal_s(ad->new_file.path, bd->new_file.path);
-		cl_assert_equal_i(ad->new_file.mode, bd->new_file.mode);
+
+		i++;
+		j++;
 	}
 }