[Bugfix] IsCountableRector & IsIterableRector should first check method availability

packages/Php/src/Rector/BinaryOp/IsCountableRector.php

@@ -61,10 +61,10 @@ CODE_SAMPLE
 
     private function shouldSkip(): bool
     {
-        if ($this->isAtLeastPhpVersion('7.3')) {
+        if (function_exists('is_countable')) {
             return false;
         }
 
-        return ! function_exists('is_countable');
+        return $this->isAtLeastPhpVersion('7.3');
     }
 }

packages/Php/src/Rector/BinaryOp/IsIterableRector.php

@@ -61,10 +61,10 @@ CODE_SAMPLE
 
     private function shouldSkip(): bool
     {
-        if ($this->isAtLeastPhpVersion('7.1')) {
+        if (function_exists('is_iterable')) {
             return false;
         }
 
-        return ! function_exists('is_iterable');
+        return $this->isAtLeastPhpVersion('7.1');
     }
 }

packages/Php/tests/Rector/BinaryOp/IsCountableRector/Fixture/fixture71.php.inc

@@ -0,0 +1,8 @@
+<?php
+
+function isCountable()
+{
+    is_array($foo) || $foo instanceof Countable;
+}
+
+?>

packages/Php/tests/Rector/BinaryOp/IsCountableRector/Fixture/polyfill_function.php.inc

@@ -0,0 +1,47 @@
+<?php
+
+namespace Rector\Php\Tests\Rector\BinaryOp\IsCountable\Fixture;
+
+use Countable;
+
+class PolyfillFunction
+{
+    public function run($foo)
+    {
+        return is_array($foo) || $foo instanceof Countable;
+    }
+}
+
+// dummy
+if (! function_exists('is_countable')) {
+    function is_countable($args)
+    {
+        return true;
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Php\Tests\Rector\BinaryOp\IsCountable\Fixture;
+
+use Countable;
+
+class PolyfillFunction
+{
+    public function run($foo)
+    {
+        return is_countable($foo);
+    }
+}
+
+// dummy
+if (! function_exists('is_countable')) {
+    function is_countable($args)
+    {
+        return true;
+    }
+}
+
+?>

packages/Php/tests/Rector/BinaryOp/IsCountableRector/IsCountableRectorTest.php

@@ -9,7 +9,13 @@ final class IsCountableRectorTest extends AbstractRectorTestCase
 {
     public function test(): void
     {
-        $this->doTestFiles([__DIR__ . '/Fixture/fixture.php.inc']);
+        // That method can be provided by `symfony/polyfill-php73` package,
+        // or not exists as it's run on PHP < 7.3
+        if (! function_exists('is_countable')) {
+            $this->doTestFiles([__DIR__ . '/Fixture/fixture71.php.inc']);
+        } else {
+            $this->doTestFiles([__DIR__ . '/Fixture/fixture73.php.inc']);
+        }
     }
 
     public function getRectorClass(): string

packages/Php/tests/Rector/BinaryOp/IsCountableRector/PolyfillRectorTest.php

@@ -0,0 +1,48 @@
+<?php declare(strict_types=1);
+
+namespace Rector\Php\Tests\Rector\BinaryOp\IsCountableRector;
+
+use Rector\Configuration\Option;
+use Rector\Php\Rector\BinaryOp\IsCountableRector;
+use Rector\Testing\PHPUnit\AbstractRectorTestCase;
+use Symplify\PackageBuilder\Parameter\ParameterProvider;
+
+final class PolyfillRectorTest extends AbstractRectorTestCase
+{
+    /**
+     * @var string|null
+     */
+    private $originalPhpVersionFeaturesParameter;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->parameterProvider = self::$container->get(ParameterProvider::class);
+        $this->originalPhpVersionFeaturesParameter = $this->parameterProvider->provideParameter(
+            Option::PHP_VERSION_FEATURES
+        );
+
+        $this->parameterProvider->changeParameter(Option::PHP_VERSION_FEATURES, '7.2');
+    }
+
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+
+        $this->parameterProvider->changeParameter(
+            Option::PHP_VERSION_FEATURES,
+            $this->originalPhpVersionFeaturesParameter
+        );
+    }
+
+    public function test(): void
+    {
+        $this->doTestFiles([__DIR__ . '/Fixture/polyfill_function.php.inc']);
+    }
+
+    public function getRectorClass(): string
+    {
+        return IsCountableRector::class;
+    }
+}

packages/Php/tests/Rector/BinaryOp/IsIterableRector/PolyfillRectorTest.php

@@ -38,7 +38,7 @@ final class PolyfillRectorTest extends AbstractRectorTestCase
 
     public function test(): void
     {
-        $this->doTestFiles([__DIR__ . '/Fixture/polyfil_function.php.inc']);
+        $this->doTestFiles([__DIR__ . '/Fixture/polyfill_function.php.inc']);
     }
 
     public function getRectorClass(): string