fixed throwing errors in exists-check functions (#54)

Suppresses warning triggered by `stat`/`lstat` when file does not exit.

By injecting another error handler which resets error reporting the
suppressed warning gets caught and does not appear in error logs.

src/NativeWrapper.php

@@ -198,14 +198,19 @@ public function unlink(string $path): bool
 
 	public function url_stat(string $path, int $flags)
 	{
+		if ($flags & STREAM_URL_STAT_QUIET) {
+			set_error_handler(static fn (): bool => true);
+		}
 		try {
 			$func = $flags & STREAM_URL_STAT_LINK ? 'lstat' : 'stat';
-			return $flags & STREAM_URL_STAT_QUIET
-				? @$this->native($func, $path)
-				: $this->native($func, $path);
+			return $this->native($func, $path);
 		} catch (\RuntimeException $e) {
 			// SplFileInfo::isFile throws exception
 			return false;
+		} finally {
+			if ($flags & STREAM_URL_STAT_QUIET) {
+				restore_error_handler();
+			}
 		}
 	}
 

tests/BypassFinals/issue52.phpt

@@ -0,0 +1,101 @@
+<?php
+
+/**
+ * @see https://github.com/dg/bypass-finals/issues/52
+ * @see https://www.php.net/manual/en/language.operators.errorcontrol.php
+ *
+ * As certain testing frameworks establish error handlers to pick up
+ * on suppressed errors, exceptions and warnings, the warning generated
+ * by `stat`/`lstat` when provided an unknown path is recorded.
+ * 
+ * `nette/tester` does _not_ detect suppressed warnings as the error handler
+ * is set right before executing the closure.
+ */
+
+declare(strict_types=1);
+
+use Tester\Assert;
+
+require __DIR__ . '/../../vendor/autoload.php';
+
+Tester\Environment::setup();
+
+DG\BypassFinals::enable();
+
+function thoroughErrorHandler(int $number, string $message, string $file, int $line): bool
+{
+	/**
+	 * NOTE: The use of the `@` operator sets the error level to
+	 *       `E_ERROR | E_CORE_ERROR | E_COMPILE_ERROR | E_USER_ERROR | E_RECOVERABLE_ERROR | E_PARSE`
+	 *       or 0 prior to PHP 8.0.0.
+	 *       Resetting the error level to `E_ALL | E_STRICT` lets the previous error handler detect
+	 *       suppressed errors, exceptions or warnings.
+	 */
+	error_reporting(E_ALL | E_STRICT);
+
+	/**
+	 * NOTE: Acquire the previous error handler from the stack and forward the error.
+	 *       Restore the error handler stack afterwards. 
+	 */
+	restore_error_handler();
+	$errorHandler = set_error_handler(null);
+	$errorHandler($number, $message, $file, $line);
+
+	return true;
+}
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	file_exists('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_writable('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_readable('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_executable('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_file('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_dir('unknown');
+
+	restore_error_handler();
+});
+
+Assert::noError(function () {
+	set_error_handler('thoroughErrorHandler');
+
+	is_link('unknown');
+
+	restore_error_handler();
+});