Util\Timing::getHumanReadableDuration: magic numbers to constants

Make the code more self-descriptive and use less "magic numbers" by declaring a couple of constants.

src/Util/Timing.php

@@ -12,6 +12,20 @@
 class Timing
 {
 
+    /**
+     * Number of milliseconds in a minute.
+     *
+     * @var int
+     */
+    const MINUTE_IN_MS = 60000;
+
+    /**
+     * Number of milliseconds in a second.
+     *
+     * @var int
+     */
+    const SECOND_IN_MS = 1000;
+
     /**
      * The start time of the run in microseconds.
      *
@@ -67,15 +81,15 @@ public static function getDuration()
     public static function getHumanReadableDuration($duration)
     {
         $timeString = '';
-        if ($duration >= 60000) {
-            $mins       = floor($duration / 60000);
-            $secs       = round((fmod($duration, 60000) / 1000), 2);
+        if ($duration >= self::MINUTE_IN_MS) {
+            $mins       = floor($duration / self::MINUTE_IN_MS);
+            $secs       = round((fmod($duration, self::MINUTE_IN_MS) / self::SECOND_IN_MS), 2);
             $timeString = $mins.' mins';
             if ($secs >= 0.01) {
                 $timeString .= ", $secs secs";
             }
-        } else if ($duration >= 1000) {
-            $timeString = round(($duration / 1000), 2).' secs';
+        } else if ($duration >= self::SECOND_IN_MS) {
+            $timeString = round(($duration / self::SECOND_IN_MS), 2).' secs';
         } else {
             $timeString = round($duration).'ms';
         }