fix: allow using empty string as the input

Author: hyf0

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "string_wizard"
-version = "0.0.8"
+version = "0.0.9"
 edition = "2021"
 license = "MIT"
 description = "manipulate string like wizards"

src/chunk.rs

@@ -39,7 +39,6 @@ pub struct Chunk<'str> {
 
 impl<'s> Chunk<'s> {
     pub fn new(span: Span) -> Self {
-        debug_assert!(span.0 < span.1);
         Self {
             span,
             ..Default::default()

src/magic_string/mutation.rs

@@ -63,6 +63,9 @@ impl<'text> MagicString<'text> {
         let start = start.assert_into_u32();
         let end = end.assert_into_u32();
         let to = to.assert_into_u32();
+        if to >= start && to <= end {
+            panic!("Cannot relocate a selection inside itself")
+        }
 
         self.split_at(start);
         self.split_at(end);

tests/magic_string.rs

@@ -287,4 +287,13 @@ mod misc {
         assert_eq!(s.remove(0, 3).to_string(), "3456");
         assert_eq!(s.remove(3, 7).to_string(), "");
     }
+
+    #[test]
+    fn allow_empty_input() {
+        let mut s = MagicString::new("");
+        s.append("xyz");
+        assert_eq!(s.to_string(), "xyz");
+        s.prepend("xyz");
+        assert_eq!(s.to_string(), "xyzxyz");
+    }
 }