Suppress notification if error_reporting() has narrowed

If the error_reporting() setting has narrowed since Airbrake's error
handler was installed, respect the new setting. This also resolves the
issue of errors suppressed with the "@" operator being reported to
Airbrake. (Fixes #105)

src/ErrorHandler.php

@@ -31,6 +31,13 @@ public function __construct(\Airbrake\Notifier $notifier)
      */
     public function onError($code, $message, $file, $line)
     {
+        // If error_reporting() setting has changed since the ErrorHandler was
+        // installed, respect the new settings. This also respects the
+        // @-operator (issue #105)
+        if ((error_reporting() & $code) === 0) {
+            return false;
+        }
+
         $this->lastError = [
             'message' => $message,
             'file' => $file,

tests/ErrorHandlerTest.php

@@ -33,6 +33,19 @@ public static function undefinedVarErrorProvider()
         ];
     }
 
+    public static function testSuppression()
+    {
+        list($notifier, $handler) = self::makeHandlerBoundNotifier();
+
+        // Cause two errors in a row, but suppress the second one. Verify that
+        // the notifier's most recent notice corresponds to the first error
+        // generated.
+        Troublemaker::echoUndefinedVar();
+        @Troublemaker::echoUndefinedIndex();
+
+        self::testPostsError($notifier);
+    }
+
     private static function makeHandlerBoundNotifier()
     {
         $notifier = new NotifierMock([

tests/Troublemaker.php

@@ -42,4 +42,15 @@ public static function newNestedException()
             return new \Exception('world', 207, $e);
         }
     }
+
+    private static function doEchoUndefinedIndex()
+    {
+        $foo = [];
+        echo $foo[0];
+    }
+
+    public static function echoUndefinedIndex()
+    {
+        self::doEchoUndefinedIndex();
+    }
 }