Preparatory changes for fix in next commit. Does not change Scintilla behaviour.

Add tests for contiguous deletions in forward and backward directions.
Use symbolic edition values.
Rename InsertionSpan to ChangeSpan and insertions to changes as holds both
insertions and deletions.
Add ChangeStack::Check.
Add comments.

1 files changed, 49 insertions, 0 deletions

diff --git a/test/unit/testCellBuffer.cxx b/test/unit/testCellBuffer.cxx
index cb69e7756..f7795c9e7 100644
--- a/test/unit/testCellBuffer.cxx
+++ b/test/unit/testCellBuffer.cxx
@@ -633,6 +633,55 @@ TEST_CASE("ChangeHistory") {
 		}
 		REQUIRE(il.DeletionCount(0, 10) == 0);
 		REQUIRE(il.Length() == 10);
+
+	}
+
+	SECTION("Delete Contiguous Backward") {
+		// Deletes that touch
+		constexpr size_t length = 20;
+		constexpr size_t rounds = 8;
+		il.Insert(0, length, false, true);
+		REQUIRE(il.Length() == length);
+		il.SetSavePoint();
+		for (size_t i = 0; i < rounds; i++) {
+			il.DeleteRangeSavingHistory(9-i, 1, false, false);
+		}
+
+		constexpr size_t lengthAfterDeletions = length - rounds;
+		REQUIRE(il.Length() == lengthAfterDeletions);
+		REQUIRE(il.DeletionCount(0, lengthAfterDeletions) == rounds);
+
+		for (size_t j = 0; j < rounds; j++) {
+			il.UndoDeleteStep(2+j, 1, false);
+		}
+
+		// Restored to original
+		REQUIRE(il.DeletionCount(0, length) == 0);
+		REQUIRE(il.Length() == length);
+	}
+
+	SECTION("Delete Contiguous Forward") {
+		// Deletes that touch
+		constexpr size_t length = 20;
+		constexpr size_t rounds = 8;
+		il.Insert(0, length, false, true);
+		REQUIRE(il.Length() == length);
+		il.SetSavePoint();
+		for (size_t i = 0; i < rounds; i++) {
+			il.DeleteRangeSavingHistory(2,1, false, false);
+		}
+
+		constexpr size_t lengthAfterDeletions = length - rounds;
+		REQUIRE(il.Length() == lengthAfterDeletions);
+		REQUIRE(il.DeletionCount(0, lengthAfterDeletions) == rounds);
+
+		for (size_t j = 0; j < rounds; j++) {
+			il.UndoDeleteStep(2, 1, false);
+		}
+
+		// Restored to original
+		REQUIRE(il.Length() == length);
+		REQUIRE(il.DeletionCount(0, length) == 0);
 	}
 }