Test coverage for nullable methods

Author: phoenix128

lib/internal/Magento/Framework/Interception/Test/Unit/Code/Generator/_files/TInterceptor.txt

@@ -25,6 +25,19 @@ class Interceptor extends \Magento\Framework\Interception\Code\Generator\TSample
         }
     }
 
+    /**
+     * {@inheritdoc}
+     */
+    public function getNullableValue() : ?string
+    {
+        $pluginInfo = $this->pluginList->getNext($this->subjectType, 'getNullableValue');
+        if (!$pluginInfo) {
+            return parent::getNullableValue();
+        } else {
+            return $this->___callPlugins('getNullableValue', func_get_args(), $pluginInfo);
+        }
+    }
+
     /**
      * {@inheritdoc}
      */

lib/internal/Magento/Framework/Interception/Test/Unit/Code/Generator/_files/TSample.php

@@ -15,6 +15,11 @@ public function returnVoid() : void
         // Nothing to do here
     }
 
+    public function getNullableValue() : ?string
+    {
+        return null;
+    }
+
     public function getValue() : string
     {
         return $this->value;