Issue #110: Add SnapshotterInterface and DiffingMultiSnapshotter.

Author: donquixote

src/Snapshotter/DiffingMultiSnapshotter.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Ock\Testing\Snapshotter;
+
+use Ock\Testing\Diff\DifferInterface;
+
+class DiffingMultiSnapshotter implements SnapshotterInterface, DifferInterface {
+
+  /**
+   * Constructor.
+   *
+   * @param array<string, \Ock\Testing\Snapshotter\SnapshotterInterface> $snapshotters
+   * @param \Ock\Testing\Diff\DifferInterface $differ
+   *   Fallback differ.
+   */
+  public function __construct(
+    private readonly array $snapshotters,
+    private readonly DifferInterface $differ,
+  ) {}
+
+  #[\Override]
+  public function takeSnapshot(): array {
+    return array_map(
+      fn (SnapshotterInterface $snapshotter) => $snapshotter->takeSnapshot(),
+      $this->snapshotters,
+    );
+  }
+
+  #[\Override]
+  public function compare(array $before, array $after): array {
+    $diff = [];
+    foreach ($this->snapshotters as $key => $snapshotter) {
+      assert(is_array($before[$key] ?? null));
+      assert(is_array($after[$key] ?? null));
+      if ($snapshotter instanceof DifferInterface) {
+        $diff[$key] = $snapshotter->compare($before[$key], $after[$key]);
+      }
+      else {
+        $diff[$key] = $this->differ->compare($before[$key], $after[$key]);
+      }
+    }
+    return $diff;
+  }
+
+}

src/Snapshotter/SnapshotterInterface.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Ock\Testing\Snapshotter;
+
+interface SnapshotterInterface {
+
+  /**
+   * Takes an exportable snapshot.
+   *
+   * @return array
+   */
+  public function takeSnapshot(): array;
+
+}