Added test for concurrent output buffer control

Author: matyhtf

tests/swoole_coroutine/output/concurrency.phpt

@@ -0,0 +1,44 @@
+--TEST--
+swoole_coroutine/output: concurrency
+--SKIPIF--
+<?php require __DIR__ . '/../../include/skipif.inc'; ?>
+--FILE--
+<?php
+require __DIR__ . '/../../include/bootstrap.php';
+ob_start();
+echo "cid 0\n";
+
+Co\run(function () {
+    ob_start();
+    echo "cid 1\n";
+
+    $list = [];
+    $n = MAX_REQUESTS;
+    while ($n--) {
+        $list[] = Co\go(function () {
+            ob_start();
+            $cid = co::getCid();
+            echo "cid {$cid} [1]\n";
+            usleep(random_int(1000, 5000));
+            echo "cid {$cid} [2]\n";
+            usleep(random_int(1000, 5000));
+            echo "cid {$cid} [3]\n";
+            usleep(random_int(1000, 5000));
+            Assert::eq(
+                ob_get_clean(),
+                implode('', [
+                    "cid {$cid} [1]\n",
+                    "cid {$cid} [2]\n",
+                    "cid {$cid} [3]\n",
+                ])
+            );
+        });
+    }
+    co::join($list);
+
+    Assert::eq(ob_get_clean(), "cid 1\n");
+});
+
+Assert::eq(ob_get_clean(), "cid 0\n");
+?>
+--EXPECT--