Fix #115 - buffer each StreamedResponse chunk when sending data to swoole worker output (#116)

* Fix #115 - buffer each `StreamedResponse` chunk when sending data to swoole worker output

This change ensures that, when converting a `StreamedResponse` to output within `php-runtime/swoole`,
the output is streamed chunk-by-chunk, instead of being buffered in its entirety, and then being
sent out to the swooler server all in one shot.

This should fix some obvious performance, latency and memory issues related to streaming common responses
assembled by PHP-side processes.

Note: you will still need to disable symfony's `StreamedResponseListener` when working with this package.

Ref: #115

* Disabled error handler replacement, which is implicitly done by the `GenericRuntime`

We don't want to replace the error handler: PHPUnit is good enough. This should bring
the tests back to green too.

* Upgrade PHPUnit configuration to comply with latest `phpunit.xsd`

Ref: https://github.com/sebastianbergmann/phpunit/blob/f61e897412fe831831462c0698a6208f7d8298f0/phpunit.xsd#L255
Ref: https://github.com/sebastianbergmann/phpunit/blob/f61e897412fe831831462c0698a6208f7d8298f0/phpunit.xsd#L16-L20

Author: Ocramius

phpunit.xml.dist

@@ -15,9 +15,9 @@
       <directory>./tests/Unit</directory>
     </testsuite>
   </testsuites>
-  <filter>
-    <whitelist processUncoveredFilesFromWhitelist="true">
+  <coverage>
+    <include>
       <directory suffix=".php">src</directory>
-    </whitelist>
-  </filter>
+    </include>
+  </coverage>
 </phpunit>

src/SymfonyHttpBridge.php

@@ -50,7 +50,7 @@ public static function reflectSymfonyResponse(SymfonyResponse $sfResponse, Respo
                     $response->write($buffer);
 
                     return '';
-                });
+                }, 4096);
                 $sfResponse->sendContent();
                 ob_end_clean();
                 $response->end();

tests/Unit/RuntimeTest.php

@@ -15,7 +15,7 @@ class RuntimeTest extends TestCase
 {
     public function testGetRunnerCreatesARunnerForCallbacks(): void
     {
-        $options = [];
+        $options = ['error_handler' => false];
         $runtime = new Runtime($options);
 
         $application = static function (): void {
@@ -27,7 +27,7 @@ public function testGetRunnerCreatesARunnerForCallbacks(): void
 
     public function testGetRunnerCreatesARunnerForSymfony(): void
     {
-        $options = [];
+        $options = ['error_handler' => false];
         $runtime = new Runtime($options);
 
         $application = $this->createMock(HttpKernelInterface::class);
@@ -38,7 +38,7 @@ public function testGetRunnerCreatesARunnerForSymfony(): void
 
     public function testGetRunnerCreatesARunnerForLaravel(): void
     {
-        $options = [];
+        $options = ['error_handler' => false];
         $runtime = new Runtime($options);
 
         $application = $this->createMock(Kernel::class);
@@ -49,7 +49,7 @@ public function testGetRunnerCreatesARunnerForLaravel(): void
 
     public function testGetRunnerFallbacksToClosureRunner(): void
     {
-        $options = [];
+        $options = ['error_handler' => false];
         $runtime = new Runtime($options);
 
         $runner = $runtime->getRunner(null);

tests/Unit/SymfonyHttpBridgeTest.php

@@ -129,4 +129,23 @@ public function testThatSymfonyBinaryFileResponseWithRangeIsReflected(): void
 
         SymfonyHttpBridge::reflectSymfonyResponse($sfResponse, $response);
     }
+
+    public function testStreamedResponseWillRespondWithOneChunkAtATime(): void
+    {
+        $sfResponse = new StreamedResponse(static function () {
+            echo str_repeat('a', 4096);
+            echo str_repeat('b', 4095);
+        });
+
+        $response = $this->createMock(Response::class);
+        $response->expects(self::exactly(2))
+            ->method('write')
+            ->with(self::logicalOr(
+                str_repeat('a', 4096),
+                str_repeat('b', 4095)
+            ));
+        $response->expects(self::once())->method('end');
+
+        SymfonyHttpBridge::reflectSymfonyResponse($sfResponse, $response);
+    }
 }