add test

Author: devnexen

ext/gmp/tests/gmp_pow_fpe.phpt

@@ -0,0 +1,22 @@
+--TEST--
+gmp_pow() floating point exception
+--EXTENSIONS--
+gmp
+--FILE--
+<?php
+$g = gmp_init(256);
+
+try {
+	gmp_pow($g, PHP_INT_MAX);
+} catch (\ValueError $e) {
+	echo $e->getMessage() . PHP_EOL;
+}
+try {
+	gmp_pow(256, PHP_INT_MAX);
+} catch (\ValueError $e) {
+	echo $e->getMessage();
+}
+?>
+--EXPECT--
+base and exponent overflow
+base and exponent overflow