Handle zero-value return from fwrite() (fixes #6)

Author: jmalloc

src/ReactApi.php

@@ -186,6 +186,12 @@ public function write(
             $length = $bufferLength;
         }
 
+        if ($length == 0) {
+            $strand->send();
+
+            return;
+        }
+
         $done = null;
         $done = $this->streamQueue->write(
             $stream,
@@ -197,7 +203,9 @@ function ($stream) use (
             ) {
                 $bytes = @\fwrite($stream, $buffer, $length);
 
-                if ($bytes === false) {
+                // zero and false both indicate an error
+                // http://php.net/manual/en/function.fwrite.php#96951
+                if ($bytes === 0 || $bytes === false) {
                     // @codeCoverageIgnoreStart
                     $done();
                     $error = \error_get_last();

test/suite/unit/ReactKernel.spec.php

@@ -5,7 +5,6 @@
 namespace Recoil\React;
 
 use Eloquent\Phony\Phony;
-use React\EventLoop\Factory;
 use React\EventLoop\LoopInterface;
 use Recoil\Kernel\Api;
 use Throwable;
@@ -22,7 +21,7 @@
     });
 
     describe('::create()', function () {
-        it('can be called without a loop', function() {
+        it('can be called without a loop', function () {
             $kernel = ReactKernel::create();
             expect($kernel)->to->be->an->instanceof(ReactKernel::class);
         });