Add tests for mysqli property writing

Forgot to git add these in the previous commit.

Author: nikic

ext/mysqli/tests/write_property.phpt

@@ -0,0 +1,43 @@
+--TEST--
+Writing to mysqli properties
+--EXTENSIONS--
+mysqli
+--FILE--
+<?php
+
+$driver = new mysqli_driver;
+try {
+    /* Read-only property */
+    $driver->client_info = 'test';
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+$driver->reconnect = 0;
+var_dump($driver->reconnect);
+$str = '4';
+$str .= '2';
+$driver->reconnect = $str;
+var_dump($driver->reconnect);
+try {
+    $driver->reconnect = [];
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+$driver->report_mode = "1";
+var_dump($driver->report_mode);
+try {
+    $driver->report_mode = [];
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+Cannot write read-only property mysqli_driver::$client_info
+bool(false)
+bool(true)
+Cannot assign array to property mysqli_driver::$reconnect of type bool
+int(1)
+Cannot assign array to property mysqli_driver::$report_mode of type int

ext/mysqli/tests/write_property_strict.phpt

@@ -0,0 +1,34 @@
+--TEST--
+Writing to mysqli properties (strict_types)
+--EXTENSIONS--
+mysqli
+--FILE--
+<?php
+
+declare(strict_types=1);
+
+$driver = new mysqli_driver;
+try {
+    /* Read-only property */
+    $driver->client_info = 42;
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    $driver->reconnect = 0;
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    $driver->report_mode = "1";
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+Cannot write read-only property mysqli_driver::$client_info
+Cannot assign int to property mysqli_driver::$reconnect of type bool
+Cannot assign string to property mysqli_driver::$report_mode of type int