Better handling of newlines in editor insert and delete

tests/editor_modified_state.rs

@@ -24,6 +24,51 @@ fn editor() -> ViEditor<'static, 'static> {
     ViEditor::new(editor)
 }
 
+fn editor_text(editor: &ViEditor<'static, 'static>) -> String {
+    let mut text = String::new();
+    editor.with_buffer(|buffer| {
+        for line in buffer.lines.iter() {
+            text.push_str(line.text());
+            text.push_str(line.ending().as_str());
+        }
+    });
+    text
+}
+
+#[test]
+fn editor_line_endings_preserved() {
+    let mut editor = editor();
+    assert_eq!(editor_text(&editor), "");
+
+    let start = Cursor::new(0, 0);
+    for &text in &[
+        "No newlines",
+        "One Newline\n",
+        "Two\nNewlines\n",
+        "LF\nCRLF\r\nCR\rLFCR\n\rNONE",
+    ] {
+        editor.start_change();
+        let end = editor.insert_at(start, text, None);
+        editor.finish_change();
+        assert_eq!(editor_text(&editor), text);
+
+        editor.start_change();
+        editor.delete_range(start, end);
+        editor.finish_change();
+        assert_eq!(editor_text(&editor), "");
+
+        editor.start_change();
+        editor.undo();
+        editor.finish_change();
+        assert_eq!(editor_text(&editor), text);
+
+        editor.start_change();
+        editor.redo();
+        editor.finish_change();
+        assert_eq!(editor_text(&editor), "");
+    }
+}
+
 // Tests that inserting into an empty editor correctly sets the editor as modified.
 #[test]
 fn insert_in_empty_editor_sets_changed() {