Don't consume deletion preceding unblamed hunk

The deletion might match subsequent unblamed hunks.

Author: cruessler

gix-blame/tests/blame.rs

@@ -565,6 +565,9 @@ fn process_change(
         }
         (Some(hunk), Some(Change::Deleted(line_number_in_destination, number_of_lines_deleted))) => {
             if line_number_in_destination < hunk.range_in_destination.start {
+                //     <--->  (hunk)
+                //  |         (line_number_in_destination)
+
                 *offset_in_destination -= number_of_lines_deleted;
 
                 let line_range_in_next_destination =
@@ -577,6 +580,9 @@ fn process_change(
 
                 (None, None)
             } else if line_number_in_destination < hunk.range_in_destination.end {
+                //  <----->  (hunk)
+                //     |     (line_number_in_destination)
+
                 if hunk.range_in_destination.start < line_number_in_destination {
                     let line_range_in_next_destination = LineRange::with_offset(
                         hunk.range_in_destination.start..line_number_in_destination,
@@ -598,9 +604,21 @@ fn process_change(
 
                 (new_hunk, None)
             } else {
-                *offset_in_destination -= number_of_lines_deleted;
+                //  <--->     (hunk)
+                //         |  (line_number_in_destination)
+
+                let line_range_in_next_destination =
+                    LineRange::with_offset(hunk.range_in_destination.clone(), *offset_in_destination);
 
-                (Some(hunk), None)
+                new_hunks_to_blame.push(UnblamedHunk::from_destination(
+                    line_range_in_next_destination.into(),
+                    hunk.offset() + *offset_in_destination,
+                ));
+
+                (
+                    None,
+                    Some(Change::Deleted(line_number_in_destination, number_of_lines_deleted)),
+                )
             }
         }
         (Some(hunk), None) => {
@@ -1534,6 +1552,36 @@ fn process_change_works_no_overlap_4() {
     assert_eq!(offset_in_destination, Offset::Added(1));
 }
 
+#[test]
+fn process_change_works_no_overlap_5() {
+    let mut lines_blamed: Vec<BlameEntry> = vec![];
+    let mut new_hunks_to_blame: Vec<UnblamedHunk> = vec![];
+    let mut offset_in_destination: Offset = Offset::Added(1);
+    let suspect = ObjectId::null(gix_hash::Kind::Sha1);
+
+    let (hunk, change) = process_change(
+        &mut lines_blamed,
+        &mut new_hunks_to_blame,
+        &mut offset_in_destination,
+        suspect,
+        // range_in_destination: 17..18
+        Some(UnblamedHunk::new(15..16, Offset::Deleted(2))),
+        Some(Change::Deleted(20, 1)),
+    );
+
+    assert_eq!(hunk, None);
+    assert_eq!(change, Some(Change::Deleted(20, 1)));
+    assert_eq!(lines_blamed, vec![]);
+    assert_eq!(
+        new_hunks_to_blame,
+        vec![UnblamedHunk {
+            range_in_blamed_file: 15..16,
+            range_in_destination: 16..17
+        }]
+    );
+    assert_eq!(offset_in_destination, Offset::Added(1));
+}
+
 #[test]
 fn process_change_works_unchanged_hunk() {
     let mut lines_blamed: Vec<BlameEntry> = vec![];
@@ -1652,17 +1700,17 @@ fn process_change_works_deleted_hunk() {
         Some(Change::Deleted(5, 3)),
     );
 
+    assert_eq!(hunk, None);
+    assert_eq!(change, Some(Change::Deleted(5, 3)));
+    assert_eq!(lines_blamed, vec![]);
     assert_eq!(
-        hunk,
-        Some(UnblamedHunk {
+        new_hunks_to_blame,
+        vec![UnblamedHunk {
             range_in_blamed_file: 0..5,
             range_in_destination: 0..5
-        })
+        }]
     );
-    assert_eq!(change, None);
-    assert_eq!(lines_blamed, vec![]);
-    assert_eq!(new_hunks_to_blame, vec![]);
-    assert_eq!(offset_in_destination, Offset::Deleted(3));
+    assert_eq!(offset_in_destination, Offset::Added(0));
 }
 
 #[test]