Add day 4

tests/Day4Test.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace Tests;
+
+use AdventOfCode21\Day4;
+
+/**
+ * @internal
+ */
+class Day4Test extends AbstractTestCase
+{
+    public static int $part1ExampleResult = 4512;
+    public static int $part1Result = 60368;
+
+    public static int $part2ExampleResult = 1924;
+    public static int $part2Result = 17435;
+
+    public function setupDay(): Day4
+    {
+        return new class() extends Day4 {
+            use ReturnTestableResults;
+        };
+    }
+}