Add test for fromCallable().

Author: Crell

Zend/tests/partial_function/closures.phpt

@@ -0,0 +1,28 @@
+--TEST--
+Converting partials to closures.
+--FILE--
+<?php
+
+function volume(int $x, int $y, int $z): int {
+    return $x * $y * $z;
+}
+
+$p = volume(3, 5, ?);
+
+// This is a useful and common way to normalize different types of callable
+// to a single API for reflection purposes.
+$c = Closure::fromCallable($p);
+$ref = new ReflectionFunction($c);
+
+print $ref->getNumberOfParameters() . PHP_EOL;
+print $ref->getParameters()[0]->getType() . PHP_EOL;
+print $ref->getParameters()[0]->getName() . PHP_EOL;
+
+print $ref->getReturnType() . PHP_EOL;
+
+?>
+--EXPECTF--
+1
+int
+z
+int