Add test for generator and pipe behavior.

Author: Crell

Zend/tests/pipe_operator/generators.phpt

@@ -0,0 +1,30 @@
+--TEST--
+Generators
+--FILE--
+<?php
+
+function producer(): \Generator {
+  yield 1;
+  yield 2;
+  yield 3;
+}
+
+function map_incr(iterable $it): \Generator {
+  foreach ($it as $val) {
+    yield $val +1;
+  }
+}
+
+$result = producer() |> map_incr(...) |> iterator_to_array(...);
+
+var_dump($result);
+?>
+--EXPECT--
+array(3) {
+  [0]=>
+  int(2)
+  [1]=>
+  int(3)
+  [2]=>
+  int(4)
+}