fix: timetable dates cannot be removed

src/app/_helpers/collections/uniq.spec.ts

@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2022 StApps
+ *  This program is free software: you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the Free
+ *  Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ *  more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with
+ *  this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {uniqBy} from './uniq';
+
+describe('uniq', function () {
+  it('should return an array with unique values', function () {
+    const array = [
+      1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
+    ];
+    const result = uniqBy(array, it => it);
+    expect(result).toEqual([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+  });
+});