diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index bf67592d8..94241454e 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -13,3 +13,34 @@ on:
 jobs:
   test:
     uses: wp-cli/.github/.github/workflows/reusable-testing.yml@main
+    with:
+      matrix: |
+        {
+          "include": [
+            {
+              "php": "8.4",
+              "wp": "latest",
+              "mysql": "mysql-8.0",
+              "os": "macos-15"
+            },
+            {
+              "php": "8.4",
+              "wp": "latest",
+              "dbtype": "sqlite",
+              "os": "macos-15"
+            },
+            {
+              "php": "8.4",
+              "wp": "latest",
+              "mysql": "mysql-8.0",
+              "os": "windows-2025"
+            },
+            {
+              "php": "8.4",
+              "wp": "latest",
+              "dbtype": "sqlite",
+              "os": "windows-2025"
+            }
+          ],
+          "exclude": []
+        }
diff --git a/bin/install-package-tests b/bin/install-package-tests
index 2646ebb1b..ec3916cdd 100755
--- a/bin/install-package-tests
+++ b/bin/install-package-tests
@@ -15,9 +15,9 @@ is_numeric() {
         *) return 0;;            # returns 0 if numeric
     esac
 }
-# Promt color vars.
-C_RED="\033[31m"
-C_BLUE="\033[34m"
+# Prompt color vars.
+C_RED="\033[0;31m"
+C_BLUE="\033[0;34m"
 NO_FORMAT="\033[0m"
 
 HOST=localhost
diff --git a/composer.json b/composer.json
index 01e690e90..e91479f32 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
         "wp-cli/config-command": "^1 || ^2",
         "wp-cli/core-command": "^1 || ^2",
         "wp-cli/eval-command": "^1 || ^2",
-        "wp-cli/wp-cli": "^2.12",
+        "wp-cli/wp-cli": "^2.13",
         "wp-coding-standards/wpcs": "^3",
         "yoast/phpunit-polyfills": "^4.0.0"
     },
diff --git a/features/steps.feature b/features/steps.feature
index 6968ba636..10fcf7384 100644
--- a/features/steps.feature
+++ b/features/steps.feature
@@ -61,7 +61,7 @@ Feature: Make sure "Given", "When", "Then" steps work as expected
   Scenario: Special variables
 
     When I run `echo {INVOKE_WP_CLI_WITH_PHP_ARGS-} cli info`
-    Then STDOUT should match /wp cli info/
+    Then STDOUT should match /(wp|wp\.bat) cli info/
     And STDERR should be empty
 
     When I run `echo {WP_VERSION-latest}`
diff --git a/features/testing.feature b/features/testing.feature
index 4bee962c4..48e714062 100644
--- a/features/testing.feature
+++ b/features/testing.feature
@@ -11,6 +11,10 @@ Feature: Test that WP-CLI loads.
 
   Scenario: WP Cron is disabled by default
     Given a WP install
+    And the wp-config.php file should contain:
+      """
+      if ( defined( 'DISABLE_WP_CRON' ) === false ) { define( 'DISABLE_WP_CRON', true ); }
+      """
     And a test_cron.php file:
       """
       <?php
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 3c2a0976c..f643eed45 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -19,8 +19,6 @@ parameters:
     - WP_DEBUG_LOG
     - WP_DEBUG_DISPLAY
   ignoreErrors:
-    # Needs fixing in WP-CLI.
-    - message: '#Parameter \#1 \$cmd of function WP_CLI\\Utils\\esc_cmd expects array<string>#'
     - message: '#Dynamic call to static method#'
       path: 'tests/tests'
   strictRules:
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index b7619f503..97c0c774b 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -11,7 +11,6 @@
 	>
 	<testsuites>
 		<testsuite name="default">
-			<directory prefix="Spec" suffix=".php">tests/</directory>
 			<directory prefix="Test" suffix=".php">tests/tests</directory>
 		</testsuite>
 	</testsuites>
diff --git a/src/Context/FeatureContext.php b/src/Context/FeatureContext.php
index 4ec3c15a3..9b81a9009 100644
--- a/src/Context/FeatureContext.php
+++ b/src/Context/FeatureContext.php
@@ -13,7 +13,6 @@
 use Behat\Behat\Hook\Scope\AfterFeatureScope;
 use Behat\Behat\Hook\Scope\BeforeFeatureScope;
 use Behat\Behat\Hook\Scope\BeforeStepScope;
-use Behat\Testwork\Hook\Scope\HookScope;
 use SebastianBergmann\CodeCoverage\Report\Clover;
 use SebastianBergmann\CodeCoverage\Driver\Selector;
 use SebastianBergmann\CodeCoverage\Driver\Xdebug;
@@ -21,7 +20,6 @@
 use SebastianBergmann\CodeCoverage\CodeCoverage;
 use SebastianBergmann\Environment\Runtime;
 use RuntimeException;
-use WP_CLI;
 use DirectoryIterator;
 use WP_CLI\Process;
 use WP_CLI\ProcessRun;
@@ -324,9 +322,9 @@ public static function get_vendor_dir(): ?string {
 		// We try to detect the vendor folder in the most probable locations.
 		$vendor_locations = [
 			// wp-cli/wp-cli-tests is a dependency of the current working dir.
-			getcwd() . '/vendor',
+			getcwd() . DIRECTORY_SEPARATOR . 'vendor',
 			// wp-cli/wp-cli-tests is the root project.
-			dirname( __DIR__, 2 ) . '/vendor',
+			dirname( __DIR__, 2 ) . DIRECTORY_SEPARATOR . 'vendor',
 			// wp-cli/wp-cli-tests is a dependency.
 			dirname( __DIR__, 4 ),
 		];
@@ -365,7 +363,7 @@ public static function get_framework_dir(): ?string {
 			// wp-cli/wp-cli is the root project.
 			dirname( $vendor_folder ),
 			// wp-cli/wp-cli is a dependency.
-			"{$vendor_folder}/wp-cli/wp-cli",
+			$vendor_folder . DIRECTORY_SEPARATOR . 'wp-cli' . DIRECTORY_SEPARATOR . 'wp-cli',
 		];
 
 		$framework_folder = '';
@@ -402,18 +400,20 @@ public static function get_bin_path(): ?string {
 		}
 
 		$bin_paths = [
-			self::get_vendor_dir() . '/bin',
-			self::get_framework_dir() . '/bin',
+			self::get_vendor_dir() . DIRECTORY_SEPARATOR . 'bin',
+			self::get_framework_dir() . DIRECTORY_SEPARATOR . 'bin',
 		];
 
+		$bin = Utils\is_windows() ? 'wp.bat' : 'wp';
+
 		foreach ( $bin_paths as $path ) {
-			if ( is_file( "{$path}/wp" ) && is_executable( "{$path}/wp" ) ) {
-				$bin_path = $path;
-				break;
+			$full_bin_path = $path . DIRECTORY_SEPARATOR . $bin;
+			if ( is_file( $full_bin_path ) && ( Utils\is_windows() || is_executable( $full_bin_path ) ) ) {
+				return $path;
 			}
 		}
 
-		return $bin_path;
+		return null;
 	}
 
 	/**
@@ -430,24 +430,32 @@ private static function get_process_env_variables(): array {
 
 		// Ensure we're using the expected `wp` binary.
 		$bin_path = self::get_bin_path();
-		wp_cli_behat_env_debug( "WP-CLI binary path: {$bin_path}" );
 
-		if ( ! file_exists( "{$bin_path}/wp" ) ) {
-			wp_cli_behat_env_debug( "WARNING: No file named 'wp' found in the provided/detected binary path." );
+		if ( ! $bin_path ) {
+			throw new RuntimeException( 'Could not find WP-CLI binary path.' );
 		}
 
-		if ( ! is_executable( "{$bin_path}/wp" ) ) {
-			wp_cli_behat_env_debug( "WARNING: File named 'wp' found in the provided/detected binary path is not executable." );
+		wp_cli_behat_env_debug( "WP-CLI binary path: {$bin_path}" );
+
+		$bin           = Utils\is_windows() ? 'wp.bat' : 'wp';
+		$full_bin_path = $bin_path . DIRECTORY_SEPARATOR . $bin;
+
+		if ( ! is_executable( $full_bin_path ) ) {
+			wp_cli_behat_env_debug( "WARNING: File named '{$bin}' found in the provided/detected binary path is not executable." );
 		}
 
-		$path_separator = Utils\is_windows() ? ';' : ':';
-		$env            = [
-			'PATH'         => $bin_path . $path_separator . getenv( 'PATH' ),
-			'BEHAT_RUN'    => 1,
-			'HOME'         => sys_get_temp_dir() . '/wp-cli-home',
-			'TEST_RUN_DIR' => self::$behat_run_dir,
+		$path_separator  = Utils\is_windows() ? ';' : ':';
+		$php_binary_path = dirname( PHP_BINARY );
+		$env             = [
+			'PATH'          => $php_binary_path . $path_separator . $bin_path . $path_separator . getenv( 'PATH' ),
+			'BEHAT_RUN'     => 1,
+			'HOME'          => sys_get_temp_dir() . '/wp-cli-home',
+			'COMPOSER_HOME' => sys_get_temp_dir() . '/wp-cli-composer-home',
+			'TEST_RUN_DIR'  => self::$behat_run_dir,
 		];
 
+		$env = array_merge( $_ENV, $env );
+
 		if ( self::running_with_code_coverage() ) {
 			$has_coverage_driver = ( new Runtime() )->hasXdebug() || ( new Runtime() )->hasPCOV();
 
@@ -565,13 +573,11 @@ private static function download_sqlite_plugin( $dir ): void {
 			mkdir( $dir );
 		}
 
-		Process::create(
-			Utils\esc_cmd(
-				'curl -sSfL %1$s > %2$s',
-				$download_url,
-				$download_location
-			)
-		)->run_check();
+		$response = Utils\http_request( 'GET', $download_url, null, [], [ 'filename' => $download_location ] );
+
+		if ( 200 !== $response->status_code ) {
+			throw new RuntimeException( "Could not download SQLite plugin (HTTP code {$response->status_code})" );
+		}
 
 		$zip          = new \ZipArchive();
 		$new_zip_file = $download_location;
@@ -655,7 +661,13 @@ public static function prepare( BeforeSuiteScope $scope ): void {
 			self::log_run_times_before_suite( $scope );
 		}
 		self::$behat_run_dir = getcwd();
-		self::$mysql_binary  = Utils\get_mysql_binary_path();
+
+		// TODO: Improve Windows support upstream in Utils\get_mysql_binary_path().
+		if ( Utils\is_windows() ) {
+			self::$mysql_binary = 'mysql.exe';
+		} else {
+			self::$mysql_binary = Utils\get_mysql_binary_path();
+		}
 
 		$result = Process::create( 'wp cli info', null, self::get_process_env_variables() )->run_check();
 		echo "{$result->stdout}\n";
@@ -699,10 +711,9 @@ public function beforeScenario( BeforeScenarioScope $scope ): void {
 			self::get_behat_internal_variables()
 		);
 
-		$mysql_binary     = Utils\get_mysql_binary_path();
 		$sql_dump_command = Utils\get_sql_dump_command();
 
-		$this->variables['MYSQL_BINARY']     = $mysql_binary;
+		$this->variables['MYSQL_BINARY']     = self::$mysql_binary;
 		$this->variables['SQL_DUMP_COMMAND'] = $sql_dump_command;
 
 		// Used in the names of the RUN_DIR and SUITE_CACHE_DIR directories.
@@ -760,6 +771,10 @@ public function afterScenario( AfterScenarioScope $scope ): void {
 	 * @param int $master_pid
 	 */
 	private static function terminate_proc( $master_pid ): void {
+		if ( Utils\is_windows() ) {
+			shell_exec( "taskkill /F /T /PID $master_pid > NUL 2>&1" );
+			return;
+		}
 
 		$output = shell_exec( "ps -o ppid,pid,command | grep $master_pid" );
 
@@ -774,6 +789,10 @@ private static function terminate_proc( $master_pid ): void {
 			}
 		}
 
+		if ( ! function_exists( 'posix_kill' ) ) {
+			return;
+		}
+
 		if ( ! posix_kill( (int) $master_pid, 9 ) ) {
 			$errno = posix_get_last_error();
 			// Ignore "No such process" error as that's what we want.
@@ -896,18 +915,19 @@ private function replace_invoke_wp_cli_with_php_args( $str ) {
 			$phar_begin     = '#!/usr/bin/env php';
 			$phar_begin_len = strlen( $phar_begin );
 			$bin_dir        = getenv( 'WP_CLI_BIN_DIR' );
+			$bin            = Utils\is_windows() ? 'wp.bat' : 'wp';
 			if ( false !== $bin_dir && file_exists( $bin_dir . '/wp' ) && file_get_contents( $bin_dir . '/wp', false, null, 0, $phar_begin_len ) === $phar_begin ) {
-				$phar_path = $bin_dir . '/wp';
+				$phar_path = $bin_dir . $bin;
 			} else {
 				$src_dir         = dirname( __DIR__, 2 );
-				$bin_path        = $src_dir . '/bin/wp';
-				$vendor_bin_path = $src_dir . '/vendor/bin/wp';
+				$bin_path        = $src_dir . '/bin/' . $bin;
+				$vendor_bin_path = $src_dir . '/vendor/bin/' . $bin;
 				if ( file_exists( $bin_path ) && is_executable( $bin_path ) ) {
 					$shell_path = $bin_path;
 				} elseif ( file_exists( $vendor_bin_path ) && is_executable( $vendor_bin_path ) ) {
 					$shell_path = $vendor_bin_path;
 				} else {
-					$shell_path = 'wp';
+					$shell_path = $bin;
 				}
 			}
 		}
@@ -1045,14 +1065,18 @@ public function build_phar( $version = 'same' ): void {
 			$this->composer_command( 'dump-autoload --working-dir=' . dirname( self::get_vendor_dir() ) );
 		}
 
-		$this->proc(
-			Utils\esc_cmd(
-				'php -dphar.readonly=0 %1$s %2$s --version=%3$s && chmod +x %2$s',
-				$make_phar_path,
-				$this->variables['PHAR_PATH'],
-				$version
-			)
-		)->run_check();
+		$command = Utils\esc_cmd(
+			'php -dphar.readonly=0 %1$s %2$s --version=%3$s',
+			$make_phar_path,
+			$this->variables['PHAR_PATH'],
+			$version
+		);
+
+		if ( ! Utils\is_windows() ) {
+			$command .= Utils\esc_cmd( ' && chmod +x %s', $this->variables['PHAR_PATH'] );
+		}
+
+		$this->proc( $command )->run_check();
 
 		// Revert the suffix change again
 		if ( $is_bundle && self::running_with_code_coverage() ) {
@@ -1078,13 +1102,11 @@ public function download_phar( $version = 'same' ): void {
 			. uniqid( 'wp-cli-download-', true )
 			. '.phar';
 
-		Process::create(
-			Utils\esc_cmd(
-				'curl -sSfL %1$s > %2$s && chmod +x %2$s',
-				$download_url,
-				$this->variables['PHAR_PATH']
-			)
-		)->run_check();
+		$response = Utils\http_request( 'GET', $download_url, null, [], [ 'filename' => $this->variables['PHAR_PATH'] ] );
+
+		if ( 200 !== $response->status_code ) {
+			throw new RuntimeException( "Could not download WP-CLI PHAR (HTTP code {$response->status_code})" );
+		}
 	}
 
 	/**
@@ -1226,20 +1248,41 @@ public function proc( $command, $assoc_args = [], $path = '' ): Process {
 	 * @param string $cmd
 	 */
 	public function background_proc( $cmd ): void {
-		$descriptors = [
-			0 => STDIN,
-			1 => [ 'pipe', 'w' ],
-			2 => [ 'pipe', 'w' ],
-		];
+		if ( Utils\is_windows() ) {
+			// On Windows, leaving pipes open can cause hangs.
+			// Redirect output to files and close stdin.
+			$stdout_file = tempnam( sys_get_temp_dir(), 'behat-stdout-' );
+			$stderr_file = tempnam( sys_get_temp_dir(), 'behat-stderr-' );
+			$descriptors = [
+				0 => [ 'pipe', 'r' ],
+				1 => [ 'file', $stdout_file, 'a' ],
+				2 => [ 'file', $stderr_file, 'a' ],
+			];
+		} else {
+			$descriptors = [
+				0 => STDIN,
+				1 => [ 'pipe', 'w' ],
+				2 => [ 'pipe', 'w' ],
+			];
+		}
 
 		$proc = proc_open( $cmd, $descriptors, $pipes, $this->variables['RUN_DIR'], self::get_process_env_variables() );
 
+		if ( Utils\is_windows() ) {
+			fclose( $pipes[0] );
+		}
+
 		sleep( 1 );
 
 		$status = proc_get_status( $proc );
 
 		if ( ! $status['running'] ) {
-			$stderr = is_resource( $pipes[2] ) ? ( ': ' . stream_get_contents( $pipes[2] ) ) : '';
+			if ( Utils\is_windows() ) {
+				$stderr = file_get_contents( $stderr_file );
+				$stderr = $stderr ? ': ' . $stderr : '';
+			} else {
+				$stderr = is_resource( $pipes[2] ) ? ( ': ' . stream_get_contents( $pipes[2] ) ) : '';
+			}
 			throw new RuntimeException( sprintf( "Failed to start background process '%s'%s.", $cmd, $stderr ) );
 		}
 
@@ -1260,7 +1303,24 @@ public function move_files( $src, $dest ): void {
 	 * @param string $dir
 	 */
 	public static function remove_dir( $dir ): void {
-		Process::create( Utils\esc_cmd( 'rm -rf %s', $dir ) )->run_check();
+		if ( ! is_dir( $dir ) ) {
+			return;
+		}
+
+		$iterator = new \RecursiveIteratorIterator(
+			new \RecursiveDirectoryIterator( $dir, \FilesystemIterator::SKIP_DOTS ),
+			\RecursiveIteratorIterator::CHILD_FIRST
+		);
+
+		foreach ( $iterator as $file ) {
+			if ( $file->isDir() ) {
+				rmdir( $file->getRealPath() );
+			} else {
+				unlink( $file->getRealPath() );
+			}
+		}
+
+		rmdir( $dir );
 	}
 
 	/**
@@ -1270,10 +1330,21 @@ public static function remove_dir( $dir ): void {
 	 * @param string $dest_dir
 	 */
 	public static function copy_dir( $src_dir, $dest_dir ): void {
-		$shell_command = ( 'Darwin' === PHP_OS )
-			? Utils\esc_cmd( 'cp -R %s/* %s', $src_dir, $dest_dir )
-			: Utils\esc_cmd( 'cp -r %s/* %s', $src_dir, $dest_dir );
-		Process::create( $shell_command )->run_check();
+		$iterator = new \RecursiveIteratorIterator(
+			new \RecursiveDirectoryIterator( $src_dir, \RecursiveDirectoryIterator::SKIP_DOTS ),
+			\RecursiveIteratorIterator::SELF_FIRST
+		);
+
+		foreach ( $iterator as $item ) {
+			$dest_path = $dest_dir . '/' . $iterator->getSubPathname();
+			if ( $item->isDir() ) {
+				if ( ! is_dir( $dest_path ) ) {
+					mkdir( $dest_path, 0777, true );
+				}
+			} else {
+				copy( $item->getPathname(), $dest_path );
+			}
+		}
 	}
 
 	/**
@@ -1377,7 +1448,7 @@ public function install_wp( $subdir = '' ): void {
 		$subdir = $this->replace_variables( $subdir );
 
 		// Disable WP Cron by default to avoid bogus HTTP requests in CLI context.
-		$config_extra_php = "if ( ! defined( 'DISABLE_WP_CRON' ) ) { define( 'DISABLE_WP_CRON', true ); }\n";
+		$config_extra_php = "if ( defined( 'DISABLE_WP_CRON' ) === false ) { define( 'DISABLE_WP_CRON', true ); }\n";
 
 		if ( 'sqlite' !== self::$db_type ) {
 			$this->create_db();
@@ -1418,7 +1489,8 @@ public function install_wp( $subdir = '' ): void {
 			if ( 'sqlite' !== self::$db_type ) {
 				$mysqldump_binary          = Utils\get_sql_dump_command();
 				$mysqldump_binary          = Utils\force_env_on_nix_systems( $mysqldump_binary );
-				$support_column_statistics = exec( "{$mysqldump_binary} --help | grep 'column-statistics'" );
+				$help_output               = shell_exec( "{$mysqldump_binary} --help" );
+				$support_column_statistics = false !== strpos( $help_output, 'column-statistics' );
 				$command                   = "{$mysqldump_binary} --no-defaults --no-tablespaces";
 				if ( $support_column_statistics ) {
 					$command .= ' --skip-column-statistics';
@@ -1452,7 +1524,7 @@ public function install_wp_with_composer( $vendor_directory = 'vendor' ): void {
 		$this->composer_command( 'require johnpbloch/wordpress-core-installer johnpbloch/wordpress-core --optimize-autoloader' );
 
 		// Disable WP Cron by default to avoid bogus HTTP requests in CLI context.
-		$config_extra_php = "if ( ! defined( 'DISABLE_WP_CRON' ) ) { define( 'DISABLE_WP_CRON', true ); }\n";
+		$config_extra_php = "if ( defined( 'DISABLE_WP_CRON' ) === false ) { define( 'DISABLE_WP_CRON', true ); }\n";
 
 		$config_extra_php .= "require_once dirname(__DIR__) . '/" . $vendor_directory . "/autoload.php';\n";
 
@@ -1527,7 +1599,14 @@ public function start_php_server( $subdir = '' ): void {
 	 */
 	private function composer_command( $cmd ): void {
 		if ( ! isset( $this->variables['COMPOSER_PATH'] ) ) {
-			$this->variables['COMPOSER_PATH'] = exec( 'which composer' );
+			$command = Utils\is_windows() ? 'where composer' : 'which composer';
+			$path    = exec( $command );
+			if ( false === $path ) {
+				throw new RuntimeException( 'Could not find composer.' );
+			}
+			// In case of multiple paths, pick the first one.
+			$path                             = strtok( $path, PHP_EOL );
+			$this->variables['COMPOSER_PATH'] = $path;
 		}
 		$this->proc( $this->variables['COMPOSER_PATH'] . ' --no-interaction ' . $cmd )->run_check();
 	}
@@ -1791,7 +1870,6 @@ function wpcli_bootstrap_behat_feature_context(): void {
 
 	// Load helper functionality that is needed for the tests.
 	require_once "{$framework_folder}/php/utils.php";
-	require_once "{$framework_folder}/php/WP_CLI/Process.php";
 	require_once "{$framework_folder}/php/WP_CLI/ProcessRun.php";
 
 	// Manually load Composer file includes by generating a config with require:
diff --git a/src/Context/GivenStepDefinitions.php b/src/Context/GivenStepDefinitions.php
index 248766a0e..5deca4b73 100644
--- a/src/Context/GivenStepDefinitions.php
+++ b/src/Context/GivenStepDefinitions.php
@@ -604,7 +604,10 @@ public function given_a_download( TableNode $table ): void {
 				continue;
 			}
 
-			Process::create( Utils\esc_cmd( 'curl -sSL %s > %s', $row['url'], $path ) )->run_check();
+			$response = Utils\http_request( 'GET', $row['url'], null, [], [ 'filename' => $path ] );
+			if ( 200 !== $response->status_code ) {
+				throw new RuntimeException( "Could not download file (HTTP code {$response->status_code})" );
+			}
 		}
 	}
 
diff --git a/tests/tests/TestBehatTags.php b/tests/tests/TestBehatTags.php
index 5b3ca49c1..5b581bc14 100644
--- a/tests/tests/TestBehatTags.php
+++ b/tests/tests/TestBehatTags.php
@@ -19,22 +19,79 @@ protected function set_up(): void {
 
 		$this->temp_dir = Utils\get_temp_dir() . uniqid( 'wp-cli-test-behat-tags-', true );
 		mkdir( $this->temp_dir );
-		mkdir( $this->temp_dir . '/features' );
+		mkdir( $this->temp_dir . DIRECTORY_SEPARATOR . 'features' );
 	}
 
 	protected function tear_down(): void {
-
 		if ( $this->temp_dir && file_exists( $this->temp_dir ) ) {
-			foreach ( glob( $this->temp_dir . '/features/*' ) as $feature_file ) {
-				unlink( $feature_file );
-			}
-			rmdir( $this->temp_dir . '/features' );
-			rmdir( $this->temp_dir );
+			$this->remove_dir( $this->temp_dir );
 		}
 
 		parent::tear_down();
 	}
 
+	/**
+	 * Recursively removes a directory and its contents.
+	 *
+	 * @param string $dir The directory to remove.
+	 */
+	private function remove_dir( $dir ): void {
+		if ( ! is_dir( $dir ) ) {
+			return;
+		}
+
+		$iterator = new \RecursiveIteratorIterator(
+			new \RecursiveDirectoryIterator( $dir, \FilesystemIterator::SKIP_DOTS ),
+			\RecursiveIteratorIterator::CHILD_FIRST
+		);
+
+		foreach ( $iterator as $file ) {
+			if ( $file->isDir() ) {
+				rmdir( $file->getRealPath() );
+			} else {
+				unlink( $file->getRealPath() );
+			}
+		}
+
+		rmdir( $dir );
+	}
+
+	/**
+	 * Runs the behat-tags.php script in a cross-platform way.
+	 *
+	 * @param string $env Environment variable string to set (e.g., 'WP_VERSION=4.5').
+	 * @return string|false The output of the script.
+	 */
+	private function run_behat_tags_script( $env = '' ) {
+		$behat_tags = dirname( dirname( __DIR__ ) ) . DIRECTORY_SEPARATOR . 'utils' . DIRECTORY_SEPARATOR . 'behat-tags.php';
+
+		// Use the `-n` flag to disable loading of `php.ini` and ensure a clean environment.
+		$php_run = escapeshellarg( PHP_BINARY ) . ' -n ' . escapeshellarg( $behat_tags );
+
+		$features_dir = $this->temp_dir . DIRECTORY_SEPARATOR . 'features';
+
+		$command = '';
+		if ( Utils\is_windows() ) {
+			// `set` is internal to `cmd.exe`. Do not escape the values, as `set` doesn't understand quotes from escapeshellarg.
+			// Note: `set "VAR=VALUE"` is more robust than `set VAR=VALUE`.
+			$command = 'set "BEHAT_FEATURES_FOLDER=' . $features_dir . '" && ';
+			if ( ! empty( $env ) ) {
+				$command .= 'set "' . $env . '" && ';
+			}
+		} else {
+			// On Unix-like systems, this sets the variable for the duration of the command.
+			$command = 'BEHAT_FEATURES_FOLDER=' . escapeshellarg( $features_dir );
+			if ( ! empty( $env ) ) {
+				$command .= ' ' . $env;
+			}
+			$command .= ' ';
+		}
+
+		$command = 'cd ' . escapeshellarg( $this->temp_dir ) . ' && ' . $command . $php_run;
+		$output  = exec( $command );
+
+		return $output;
+	}
 	/**
 	 * @dataProvider data_behat_tags_wp_version_github_token
 	 *
@@ -50,12 +107,10 @@ public function test_behat_tags_wp_version_github_token( $env, $expected ): void
 		putenv( 'WP_VERSION' );
 		putenv( 'GITHUB_TOKEN' );
 
-		$behat_tags = dirname( dirname( __DIR__ ) ) . '/utils/behat-tags.php';
-
 		$contents = '@require-wp-4.6 @require-wp-4.8 @require-wp-4.9 @less-than-wp-4.6 @less-than-wp-4.8 @less-than-wp-4.9';
-		file_put_contents( $this->temp_dir . '/features/wp_version.feature', $contents );
+		file_put_contents( $this->temp_dir . DIRECTORY_SEPARATOR . 'features' . DIRECTORY_SEPARATOR . 'wp_version.feature', $contents );
 
-		$output = exec( "cd {$this->temp_dir}; $env php $behat_tags" );
+		$output = $this->run_behat_tags_script( $env );
 
 		$expected .= '&&~@broken';
 		if ( in_array( $env, array( 'WP_VERSION=trunk', 'WP_VERSION=nightly' ), true ) ) {
@@ -109,8 +164,6 @@ public function test_behat_tags_php_version(): void {
 
 		putenv( 'GITHUB_TOKEN' );
 
-		$behat_tags = dirname( dirname( __DIR__ ) ) . '/utils/behat-tags.php';
-
 		$php_version = substr( PHP_VERSION, 0, 3 );
 		$contents    = '';
 		$expected    = '';
@@ -163,9 +216,9 @@ public function test_behat_tags_php_version(): void {
 				break;
 		}
 
-		file_put_contents( $this->temp_dir . '/features/php_version.feature', $contents );
+		file_put_contents( $this->temp_dir . DIRECTORY_SEPARATOR . 'features' . DIRECTORY_SEPARATOR . 'php_version.feature', $contents );
 
-		$output = exec( "cd {$this->temp_dir}; php $behat_tags" );
+		$output = $this->run_behat_tags_script();
 		$this->assertSame( '--tags=' . $expected, $output );
 
 		putenv( false === $env_github_token ? 'GITHUB_TOKEN' : "GITHUB_TOKEN=$env_github_token" );
@@ -177,9 +230,7 @@ public function test_behat_tags_extension(): void {
 
 		putenv( 'GITHUB_TOKEN' );
 
-		$behat_tags = dirname( dirname( __DIR__ ) ) . '/utils/behat-tags.php';
-
-		file_put_contents( $this->temp_dir . '/features/extension.feature', '@require-extension-imagick @require-extension-curl' );
+		file_put_contents( $this->temp_dir . DIRECTORY_SEPARATOR . 'features' . DIRECTORY_SEPARATOR . 'extension.feature', '@require-extension-imagick @require-extension-curl' );
 
 		$expecteds = array();
 
@@ -200,15 +251,18 @@ public function test_behat_tags_extension(): void {
 				break;
 		}
 
-		if ( ! extension_loaded( 'imagick' ) ) {
+		// Check which extensions are loaded in the clean `php -n` environment to build the correct expectation.
+		$imagick_loaded_in_script = (bool) exec( 'cd ' . escapeshellarg( $this->temp_dir ) . ' && ' . escapeshellarg( PHP_BINARY ) . ' -n -r "echo (int)extension_loaded(\'imagick\');"' );
+		if ( ! $imagick_loaded_in_script ) {
 			$expecteds[] = '~@require-extension-imagick';
 		}
-		if ( ! extension_loaded( 'curl' ) ) {
+		$curl_loaded_in_script = (bool) exec( 'cd ' . escapeshellarg( $this->temp_dir ) . ' && ' . escapeshellarg( PHP_BINARY ) . ' -n -r "echo (int)extension_loaded(\'curl\');"' );
+		if ( ! $curl_loaded_in_script ) {
 			$expecteds[] = '~@require-extension-curl';
 		}
 
 		$expected = '--tags=' . implode( '&&', array_merge( array( '~@github-api', '~@broken' ), $expecteds ) );
-		$output   = exec( "cd {$this->temp_dir}; php $behat_tags" );
+		$output   = $this->run_behat_tags_script();
 		$this->assertSame( $expected, $output );
 
 		putenv( false === $env_github_token ? 'GITHUB_TOKEN' : "GITHUB_TOKEN=$env_github_token" );
@@ -217,8 +271,13 @@ public function test_behat_tags_extension(): void {
 	public function test_behat_tags_db_version(): void {
 		$db_type = getenv( 'WP_CLI_TEST_DBTYPE' );
 
-		$behat_tags = dirname( dirname( __DIR__ ) ) . '/utils/behat-tags.php';
+		$behat_tags = dirname( dirname( __DIR__ ) ) . DIRECTORY_SEPARATOR . 'utils' . DIRECTORY_SEPARATOR . 'behat-tags.php';
+
+		// Just to get the get_db_version() function. Prevents unexpected output.
+		ob_start();
 		require $behat_tags;
+		ob_end_clean();
+
 		// @phpstan-ignore-next-line
 		$db_version         = get_db_version();
 		$minimum_db_version = $db_version . '.1';
@@ -249,10 +308,10 @@ public function test_behat_tags_db_version(): void {
 				break;
 		}
 
-		file_put_contents( $this->temp_dir . '/features/extension.feature', $contents );
+		file_put_contents( $this->temp_dir . DIRECTORY_SEPARATOR . 'features' . DIRECTORY_SEPARATOR . 'extension.feature', $contents );
 
 		$expected = '--tags=' . implode( '&&', array_merge( array( '~@github-api', '~@broken' ), $expecteds ) );
-		$output   = exec( "cd {$this->temp_dir}; php $behat_tags" );
+		$output   = $this->run_behat_tags_script();
 		$this->assertSame( $expected, $output );
 	}
 }
diff --git a/utils/behat-tags.php b/utils/behat-tags.php
index c6fa9833e..c11c49d57 100644
--- a/utils/behat-tags.php
+++ b/utils/behat-tags.php
@@ -23,10 +23,17 @@ function version_tags(
 		return array();
 	}
 
-	exec(
-		"grep '@{$prefix}-[0-9\.]*' -h -o {$features_folder}/*.feature | uniq",
-		$existing_tags
-	);
+	$existing_tags = array();
+	$feature_files = glob( $features_folder . DIRECTORY_SEPARATOR . '*.feature' );
+	if ( ! empty( $feature_files ) ) {
+		foreach ( $feature_files as $feature_file ) {
+			$contents = file_get_contents( $feature_file );
+			if ( preg_match_all( '/@' . $prefix . '-[0-9\.]+/', $contents, $matches ) ) {
+				$existing_tags = array_merge( $existing_tags, $matches[0] );
+			}
+		}
+		$existing_tags = array_unique( $existing_tags );
+	}
 
 	$skip_tags = array();
 
@@ -41,7 +48,11 @@ function version_tags(
 }
 
 function get_db_version() {
-	$version_string = exec( getenv( 'WP_CLI_TEST_DBTYPE' ) === 'mariadb' ? 'mariadb --version' : 'mysql -V' );
+	$db_type = getenv( 'WP_CLI_TEST_DBTYPE' );
+	if ( 'sqlite' === $db_type ) {
+		return '';
+	}
+	$version_string = exec( 'mariadb' === $db_type ? 'mariadb --version' : 'mysql -V' );
 	preg_match( '@[0-9]+\.[0-9]+\.[0-9]+@', $version_string, $version );
 	return $version[0];
 }
@@ -85,11 +96,11 @@ function get_db_version() {
 	$skip_tags[] = '@broken-trunk';
 }
 
-$db_version = get_db_version();
 
 switch ( getenv( 'WP_CLI_TEST_DBTYPE' ) ) {
 	case 'mariadb':
-		$skip_tags = array_merge(
+		$db_version = get_db_version();
+		$skip_tags  = array_merge(
 			$skip_tags,
 			[ '@require-mysql', '@require-sqlite' ],
 			version_tags( 'require-mariadb', $db_version, '<', $features_folder ),
@@ -103,7 +114,8 @@ function get_db_version() {
 		break;
 	case 'mysql':
 	default:
-		$skip_tags = array_merge(
+		$db_version = get_db_version();
+		$skip_tags  = array_merge(
 			$skip_tags,
 			[ '@require-mariadb', '@require-sqlite' ],
 			version_tags( 'require-mysql', $db_version, '<', $features_folder ),
@@ -115,10 +127,16 @@ function get_db_version() {
 # Require PHP extension, eg 'imagick'.
 function extension_tags( $features_folder = 'features' ) {
 	$extension_tags = array();
-	exec(
-		"grep '@require-extension-[A-Za-z_]*' -h -o {$features_folder}/*.feature | uniq",
-		$extension_tags
-	);
+	$feature_files  = glob( $features_folder . DIRECTORY_SEPARATOR . '*.feature' );
+	if ( ! empty( $feature_files ) ) {
+		foreach ( $feature_files as $feature_file ) {
+			$contents = file_get_contents( $feature_file );
+			if ( preg_match_all( '/@require-extension-[A-Za-z_]*/', $contents, $matches ) ) {
+				$extension_tags = array_merge( $extension_tags, $matches[0] );
+			}
+		}
+		$extension_tags = array_unique( $extension_tags );
+	}
 
 	$skip_tags = array();