Generic/NestingLevel: improve code coverage

src/Standards/Generic/Tests/Metrics/NestingLevelUnitTest.1.inc

@@ -99,4 +99,10 @@ function nestingEleven()
     }
 }
 
-?>
+abstract class AbstractClass {
+    abstract public function sniffShouldIgnoreAbstractMethods();
+}
+
+interface MyInterface {
+    public function sniffShouldIgnoreInterfaceMethods();
+}

src/Standards/Generic/Tests/Metrics/NestingLevelUnitTest.2.inc

@@ -0,0 +1,7 @@
+<?php
+
+// Intentional parse error (missing opening curly bracket).
+// This should be the only test in this file.
+// Testing that the sniff is *not* triggered.
+
+function sniffShouldBailMissingScopeOpener()

src/Standards/Generic/Tests/Metrics/NestingLevelUnitTest.3.inc

@@ -0,0 +1,7 @@
+<?php
+
+// Intentional parse error (missing closing curly bracket).
+// This should be the only test in this file.
+// Testing that the sniff is *not* triggered.
+
+function sniffShouldBailMissingScopeCloser() {