feature #12666 [Hackday][Stopwatch] added __toString on StopwatchEvent (damienalexandre)

This PR was merged into the 2.7 branch.

Discussion
----------

[Hackday][Stopwatch] added __toString on StopwatchEvent

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #12152
| License       | MIT
| Doc PR        | no

This allow to just print the events in a log or something.

```php
$stopwatch = new Stopwatch();
$event = $stopwatch->start('foo', 'cat');

echo $event; // cat: 0.00 MiB - 0 ms
```

Commits
-------

0b88a23 [Stopwatch] added __toString on StopwatchEvent

src/Symfony/Component/Stopwatch/StopwatchEvent.php

@@ -234,4 +234,12 @@ class StopwatchEvent
 
         return round($time, 1);
     }
+
+    /**
+     * @return string
+     */
+    public function __toString()
+    {
+        return sprintf('%s: %.2F MiB - %d ms', $this->getCategory(), $this->getMemory() / 1024 / 1024, $this->getDuration());
+    }
 }

src/Symfony/Component/Stopwatch/Tests/StopwatchEventTest.php

@@ -156,4 +156,16 @@ class StopwatchEventTest extends \PHPUnit_Framework_TestCase
     {
         new StopwatchEvent("abc");
     }
+
+    public function testHumanRepresentation()
+    {
+        $event = new StopwatchEvent(microtime(true) * 1000);
+        $this->assertEquals('default: 0.00 MiB - 0 ms', (string) $event);
+        $event->start();
+        $event->stop();
+        $this->assertEquals(1, preg_match('/default: [0-9\.]+ MiB - [0-9]+ ms/', (string) $event));
+
+        $event = new StopwatchEvent(microtime(true) * 1000, 'foo');
+        $this->assertEquals('foo: 0.00 MiB - 0 ms', (string) $event);
+    }
 }