revert tests

Author: sanmai

tests/Inference/FilterTypeNarrowingSimpleTest.php

@@ -118,6 +118,20 @@ public function testFilterStrictModeKeepsFalsyValues(): void
     /**
      * Tests that is_int(...) narrows types correctly.
      */
+    public function testFilterWithIsInt(): void
+    {
+        /** @var Standard<int, int|string|float> $pipeline */
+        $pipeline = take([1, 'hello', 3.14, 42, 'world', 2.71]);
+
+        // After filter(is_int(...)), PHPStan should know this contains only ints
+        $result = $pipeline
+            ->filter(is_int(...))
+            ->map(fn(int $n) => yield $n * $n)
+            ->toList();
+
+        $this->assertSame([1, 1764], $result);
+    }
+
     /**
      * Tests that 'is_array' string callback narrows types correctly.
      */
@@ -138,6 +152,21 @@ public function testFilterWithIsArrayCallback(): void
     /**
      * Tests that multiple filters work together for type narrowing.
      */
+    public function testChainedFilters(): void
+    {
+        /** @var Standard<int, int|string|null> $pipeline */
+        $pipeline = take([1, 'hello', null, 42, 'world']);
+
+        // Chain filters: first remove nulls, then keep only strings
+        $result = $pipeline
+            ->filter(strict: true)  // Removes null
+            ->filter(is_string(...))  // Keeps only strings
+            ->cast(fn(string $s) => strtoupper($s))
+            ->toList();
+
+        $this->assertSame(['HELLO', 'WORLD'], $result);
+    }
+
     /**
      * Tests that the extension works with complex union types.
      */