Added test to confirm, that opened windows are closed by the Session::reset call

tests/Js/SessionResetTest.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace Behat\Mink\Tests\Driver\Js;
+
+use Behat\Mink\Tests\Driver\TestCase;
+
+final class SessionResetTest extends TestCase
+{
+    /**
+     * @dataProvider initialWindowNameDataProvider
+     */
+    public function testSessionResetClosesWindows(?string $initialWindowName): void
+    {
+        $session = $this->getSession();
+        $session->visit($this->pathTo('/window.html'));
+
+        if (null !== $initialWindowName) {
+            $session->executeScript('window.name = "'.$initialWindowName.'";');
+        }
+
+        $page = $session->getPage();
+
+        $page->clickLink('Popup #1');
+        $page->clickLink('Popup #2');
+
+        $expectedInitialWindowName = $session->evaluateScript('window.name');
+
+        $windowNames = $session->getWindowNames();
+        $this->assertCount(3, $windowNames, 'Incorrect opened window count.'); // Initial window + 2 opened popups.
+
+        $session->reset();
+
+        $windowNames = $session->getWindowNames();
+        $this->assertCount(1, $windowNames, 'Incorrect opened window count.'); // Initial window only.
+
+        $actualInitialWindowName = $session->evaluateScript('window.name');
+        $this->assertEquals($expectedInitialWindowName, $actualInitialWindowName, 'Not inside an initial window.');
+    }
+
+    public static function initialWindowNameDataProvider(): array
+    {
+        return array(
+            'no name' => array(null),
+            'non-empty name' => array('initial-window'),
+        );
+    }
+
+    /**
+     * @after
+     */
+    protected function resetSessions()
+    {
+        $session = $this->getSession();
+
+        // Stop the session instead of resetting, because resetting behavior is being tested.
+        if ($session->isStarted()) {
+            $session->stop();
+        }
+
+        parent::resetSessions();
+    }
+}