Organize test suites into unit and integration

This is the goals of project organization composing different
combinations to run any number of tests together.

tests/unit/Support/Calendar/Periodicity/WeeklyTest.php

@@ -0,0 +1,48 @@
+<?php
+
+/**
+ * Copyright (c) 2023 james@firefly-iii.org
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+namespace Tests\unit\Support\Calendar\Periodicity;
+
+use Carbon\Carbon;
+use FireflyIII\Support\Calendar\Periodicity;
+use FireflyIII\Support\Calendar\Periodicity\Interval;
+
+/**
+ * @group unit-test
+ * @group support
+ * @group calendar
+ * @group periodicity
+ */
+class WeeklyTest extends IntervalTestCase
+{
+    public static function factory(): Interval
+    {
+        return new Periodicity\Weekly();
+    }
+
+    public static function provideIntervals(): array
+    {
+        return [
+            new IntervalProvider(Carbon::now(), Carbon::now()->addWeek()),
+            new IntervalProvider(Carbon::parse('2023-01-31'), Carbon::parse('2023-02-07')),
+        ];
+    }
+}