Generic/InterfaceNameSuffix: improve code coverage

- Add a separate test case file with a live coding/parse error test.
- Add a new test with comments and new lines in unexpected places and
parent interfaces.

Author: rodrigoprimo

src/Standards/Generic/Tests/NamingConventions/InterfaceNameSuffixUnitTest.1.inc

@@ -5,3 +5,9 @@ interface SomeNameInterface {}
 interface MissingInterfaceSuffix {} // Error.
 
 interface CaseOfSuffixIsNotEnforced_interFACE {}
+
+interface
+    /*comment*/
+    InterfaceAnotherInvalidName
+    extends
+    AnotherInterface, \Countable {} // Error.

src/Standards/Generic/Tests/NamingConventions/InterfaceNameSuffixUnitTest.2.inc

@@ -0,0 +1,7 @@
+<?php
+
+// Intentional parse error (no interface name).
+// This should be the only test in this file.
+// Testing that the sniff is *not* triggered.
+
+interface

src/Standards/Generic/Tests/NamingConventions/InterfaceNameSuffixUnitTest.php

@@ -33,7 +33,10 @@ public function getErrorList($testFile='')
     {
         switch ($testFile) {
         case 'InterfaceNameSuffixUnitTest.1.inc':
-            return [5 => 1];
+            return [
+                5 => 1,
+                9 => 1,
+            ];
         default:
             return [];
         }