fix: allowed overwrite across moved content preceded by split (#192)

Co-authored-by: Anthony Fu <[email protected]>

src/MagicString.js

@@ -372,21 +372,16 @@ export default class MagicString {
 		const last = this.byEnd[end];
 
 		if (first) {
-			if (end > first.end && first.next !== this.byStart[first.end]) {
-				throw new Error('Cannot overwrite across a split point');
-			}
-
-			first.edit(content, storeName, contentOnly);
-
-			if (first !== last) {
-				let chunk = first.next;
-				while (chunk !== last) {
-					chunk.edit('', false);
-					chunk = chunk.next;
+			let chunk = first;
+			while (chunk !== last) {
+				if (chunk.next !== this.byStart[chunk.end]) {
+					throw new Error('Cannot overwrite across a split point');
 				}
-
+				chunk = chunk.next;
 				chunk.edit('', false);
 			}
+
+			first.edit(content, storeName, contentOnly);
 		} else {
 			// must be inserting at the end
 			const newChunk = new Chunk(start, end, '').edit(content, storeName);

test/MagicString.js

@@ -824,13 +824,28 @@ describe('MagicString', () => {
 			assert.equal(s.toString(), 'a&^...!?defghijkl');
 		});
 
-		it('disallows overwriting across moved content', () => {
+		it('disallows overwriting partially overlapping moved content', () => {
 			const s = new MagicString('abcdefghijkl');
 
 			s.move(6, 9, 3);
 			assert.throws(() => s.overwrite(5, 7, 'XX'), /Cannot overwrite across a split point/);
 		});
 
+		it('disallows overwriting fully surrounding content moved away', () => {
+			const s = new MagicString('abcdefghijkl');
+
+			s.move(6, 9, 3);
+			assert.throws(() => s.overwrite(4, 11, 'XX'), /Cannot overwrite across a split point/);
+		});
+
+		it('disallows overwriting fully surrounding content moved away even if there is another split', () => {
+			const s = new MagicString('abcdefghijkl');
+
+			s.move(6, 9, 3);
+			s.appendLeft(5, 'foo');
+			assert.throws(() => s.overwrite(4, 11, 'XX'), /Cannot overwrite across a split point/);
+		});
+
 		it('allows later insertions at the end', () => {
 			const s = new MagicString('abcdefg');