Add test case for bill dates

tests/unit/Support/Calendar/CalculatorTest.php

@@ -28,7 +28,6 @@ namespace Tests\unit\Support\Calendar;
 use FireflyIII\Exceptions\IntervalException;
 use FireflyIII\Support\Calendar\Calculator;
 use FireflyIII\Support\Calendar\Periodicity;
-use Generator;
 use PHPUnit\Framework\TestCase;
 use Tests\unit\Support\Calendar\Periodicity\BimonthlyTest;
 use Tests\unit\Support\Calendar\Periodicity\DailyTest;

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

@@ -26,7 +26,6 @@ declare(strict_types=1);
 namespace Tests\unit\Support\Calendar\Periodicity;
 
 use FireflyIII\Support\Calendar\Periodicity\Interval;
-use Generator;
 use PHPUnit\Framework\TestCase;
 
 abstract class IntervalTestCase extends TestCase

tests/unit/Support/NavigationEndOfPeriodTest.php

@@ -43,6 +43,9 @@ class NavigationEndOfPeriodTest extends TestCase
         $this->navigation = new Navigation();
     }
 
+    /**
+     * @return iterable
+     */
     public static function provideDates(): iterable
     {
         return [