SortedNotesFolder: Add another test

lib/core/sorted_notes_folder.dart

@@ -1,3 +1,5 @@
+import 'dart:math';
+
 import 'package:fimber/fimber.dart';
 import 'package:flutter/material.dart';
 import 'package:gitjournal/core/sorting_mode.dart';
@@ -80,26 +82,49 @@ class SortedNotesFolder with NotesFolderNotifier implements NotesFolder {
   }
 
   int _insertInCorrectPos(Note note) {
+    if (_notes.isEmpty) {
+      _notes.add(note);
+      return 0;
+    }
+
     var i = _getInsertPos(note, 0, _notes.length - 1);
-    _notes.insert(i, note);
+    if (i == _notes.length) {
+      _notes.add(note);
+    } else {
+      _notes.insert(i, note);
+    }
     return i;
   }
 
   int _getInsertPos(Note note, int low, int high) {
-    int mid;
+    assert(low <= high);
+
+    int mid = high;
+
     while (low <= high) {
       mid = low + ((high - low) ~/ 2);
 
       var r = _sortFunc(_notes[mid], note);
       if (r == 0) {
-        return mid;
+        return low;
-      } else if (r < 0) {
+      }
+
+      if (low == high) {
+        if (r < 0) {
+          return low + 1;
+        } else {
+          return low;
+        }
+      }
+
+      if (r < 0) {
         low = mid + 1;
       } else {
-        high = mid - 1;
+        high = max(low, mid - 1);
       }
     }
 
+    assert(false);
     return mid;
   }
 

test/sorted_notes_folder_test.dart

@@ -91,5 +91,29 @@ void main() {
       expect(sf.notes[4].body, "1");
       expect(sf.notes[5].body, "0");
     });
+
+    test('If still sorted while loading the notes', () async {
+      var folder = NotesFolderFS(null, tempDir.path);
+      var sf = SortedNotesFolder(
+        folder: folder,
+        sortingMode: SortingMode.Modified,
+      );
+
+      await folder.loadRecursively();
+
+      expect(sf.hasNotes, true);
+      expect(sf.isEmpty, false);
+      expect(sf.name.startsWith("__sorted_folder_test__"), true);
+      expect(sf.subFolders.length, 0);
+      expect(sf.notes.length, 5);
+
+      expect(sf.notes[0].body, "4");
+      expect(sf.notes[1].body, "3");
+      expect(sf.notes[2].body, "2");
+      expect(sf.notes[3].body, "1");
+      expect(sf.notes[4].body, "0");
+    });
+
+    // FIXME: Test if adding a note to the end works
   });
 }