test: add unit test for getFormattedTimeDiff() in SingleEventData

tests/phpunit/tests/Helper/SingleEventData.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace EventManagerIntegration\tests\Helper;
+
+use EventManagerIntegration\Helper\SingleEventData;
+use WP_Mock\Tools\TestCase;
+
+class SingleEventDataTest extends TestCase {
+
+    /**
+     * @testdox getFormattedTimeDiff() should return the formatted time difference between two timestamps without rounding minutes.
+     */
+    public function testGetFormattedTimeDiff() {
+        define('DAY_IN_SECONDS', 86400);
+        define('HOUR_IN_SECONDS', 3600);
+        define('MINUTE_IN_SECONDS', 60);
+
+        $start = strtotime('2021-01-01 12:00:00');
+        $end = strtotime('2021-01-01 13:31:30');
+        $this->assertEquals('1 hour 31 mins', SingleEventData::getFormattedTimeDiff($start, $end));
+    }
+}