Add a KeyValueGraph test class for displaying graphs with a key and a value.

Author: drupol

tests/src/Exporter/KeyValueGraph.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace drupol\phptree\tests\Exporter;
+
+use drupol\phptree\Node\NodeInterface;
+use Fhaculty\Graph\Vertex;
+
+/**
+ * Class KeyValueGraph
+ */
+class KeyValueGraph extends ValueGraph
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function createVertex(NodeInterface $node): Vertex
+    {
+        $vertex = parent::createVertex($node);
+
+        if (\method_exists($node, 'getValue') && \method_exists($node, 'getKey')) {
+            $vertex->setAttribute('graphviz.label', $node->getValue());
+        }
+
+        return $vertex;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function createVertexId(NodeInterface $node)
+    {
+        if (\method_exists($node, 'getValue') && \method_exists($node, 'getKey')) {
+            return $node->getKey() . $node->getValue();
+        }
+
+        return \sha1((string) parent::createVertexId($node));
+    }
+}