Add snapshot tests to PHPUnit

tests/Unit/SnapshotTest.php

@@ -0,0 +1,70 @@
+<?php
+
+namespace App\Tests;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Finder\Finder;
+
+/**
+ * @group snapshots
+ */
+class SnapshotTest extends TestCase
+{
+    /**
+     * @var array<int, string>
+     */
+    private static $configs = [
+        'drupal',
+        'drupal-commerce-kickstart',
+        'drupal-localgov',
+    ];
+
+    public function testCompareFiles(): void
+    {
+        foreach (self::$configs as $config) {
+            $baseDir = getcwd() . "/tests/snapshots/output/{$config}";
+            $generatedDir = getcwd() . "/.ignored/snapshots/output/{$config}";
+
+            $this->runCliTool($config);
+
+            $baseFiles = $this->getFiles($baseDir);
+
+            foreach ($baseFiles as $file) {
+                $this->assertFileEquals(
+                    expected: $baseDir . '/' . $file,
+                    actual: $generatedDir . '/' . $file,
+                    message: "Files do not match: {$file}",
+                );
+            }
+        }
+    }
+
+    private function runCliTool(string $config): void
+    {
+        $cliCommand = sprintf(
+            "%s app:generate --config-file %s --output-dir %s",
+            getcwd() . '/bin/build-configs',
+            getcwd() . "/tests/snapshots/configs/{$config}.yaml",
+            getcwd() . "/.ignored/snapshots/output/{$config}",
+        );
+
+        exec($cliCommand);
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    private function getFiles(string $directory): array
+    {
+        $files = [];
+
+        $finder = new Finder();
+        $finder->in($directory)->files();
+
+        foreach ($finder as $file) {
+            $files[] = $file->getRelativePathname();
+        }
+
+        return $files;
+    }
+}