tests: Add missing static analysis tests.

tests/static-analysis/when.php

@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+include __DIR__ . '/../../vendor/autoload.php';
+
+use loophp\collection\Collection;
+use loophp\collection\Contract\Collection as CollectionInterface;
+
+/**
+ * @param CollectionInterface<int, string> $collection
+ */
+function whenConditionIsTrueT_checkList(CollectionInterface $collection): void
+{
+}
+
+/**
+ * @param CollectionInterface<int, int> $collection
+ */
+function whenConditionIsFalseT_checkList(CollectionInterface $collection): void
+{
+}
+
+whenConditionIsTrueT_checkList(
+    Collection::fromIterable(range('a', 'e'))
+        ->when(
+            static fn() => true,
+            static fn() => range('a', 'e'),
+            static fn() => range('a', 'e')
+        )
+    );
+
+whenConditionIsTrueT_checkList(
+    Collection::fromIterable(range('a', 'e'))
+        ->when(
+            static fn() => true,
+            static fn() => range('a', 'e')
+        )
+    );
+
+whenConditionIsFalseT_checkList(
+    Collection::fromIterable(range(0, 4))
+        ->when(
+            static fn() => false,
+            static fn() => range(0, 4),
+            static fn() => range(0, 4)
+        )
+    );