Change offset for changes when there is no hunk

At this point, this is not strictly necessary as the changes to
`offset_in_destination` are not read anywhere yet after they are changed
in the added branches.

Author: cruessler

gix-blame/tests/blame.rs

@@ -611,7 +611,18 @@ fn process_change(
 
             (None, None)
         }
-        (None, Some(_)) => (None, None),
+        (None, Some(Change::Unchanged(_))) => (None, None),
+        (None, Some(Change::Added(added, number_of_lines_deleted))) => {
+            *offset_in_destination += added.end - added.start;
+            *offset_in_destination -= number_of_lines_deleted;
+
+            (None, None)
+        }
+        (None, Some(Change::Deleted(_, number_of_lines_deleted))) => {
+            *offset_in_destination -= number_of_lines_deleted;
+
+            (None, None)
+        }
         (None, None) => (None, None),
     }
 }
@@ -1706,6 +1717,74 @@ fn process_change_works_deleted_hunk_3() {
     assert_eq!(offset_in_destination, Offset::Deleted(4));
 }
 
+#[test]
+fn process_change_works_addition_only() {
+    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,
+        None,
+        Some(Change::Added(22..25, 1)),
+    );
+
+    assert_eq!(hunk, None);
+    assert_eq!(change, None);
+    assert_eq!(lines_blamed, vec![]);
+    assert_eq!(new_hunks_to_blame, vec![]);
+    assert_eq!(offset_in_destination, Offset::Added(3));
+}
+
+#[test]
+fn process_change_works_deletion_only() {
+    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,
+        None,
+        Some(Change::Deleted(11, 5)),
+    );
+
+    assert_eq!(hunk, None);
+    assert_eq!(change, None);
+    assert_eq!(lines_blamed, vec![]);
+    assert_eq!(new_hunks_to_blame, vec![]);
+    assert_eq!(offset_in_destination, Offset::Deleted(4));
+}
+
+#[test]
+fn process_change_works_unchanged_only() {
+    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,
+        None,
+        Some(Change::Unchanged(11..13)),
+    );
+
+    assert_eq!(hunk, None);
+    assert_eq!(change, None);
+    assert_eq!(lines_blamed, vec![]);
+    assert_eq!(new_hunks_to_blame, vec![]);
+    assert_eq!(offset_in_destination, Offset::Added(1));
+}
 #[test]
 fn process_changes_works() {
     let mut lines_blamed: Vec<BlameEntry> = vec![];