Return value from RemoteFilesystem->copy

RemoteFilesystem did not return the value from parent::copy and would
fail the improved unit test (inspired by the unit test for the copy
method of composer).

See:
https://github.com/composer/composer/blob/master/tests/Composer/Test/Util/RemoteFilesystemTest.php

src/ACFProInstaller/RemoteFilesystem.php

@@ -59,7 +59,7 @@ public function copy(
         $progress = true,
         $options = []
     ) {
-        parent::copy(
+        return parent::copy(
             $originUrl,
             $this->acfFileUrl,
             $fileName,

tests/ACFProInstaller/RemoteFilesystemTest.php

@@ -9,29 +9,28 @@ class RemoteFilesystemTest extends \PHPUnit_Framework_TestCase
 
     protected function setUp()
     {
-        $this->io = $this->getMockBuilder('Composer\IO\IOInterface')->getMock();
-        $this->config = $this->getMockBuilder('Composer\Config')->getMock();
+        $this->io = $this->getMock('Composer\IO\IOInterface');
     }
 
     public function testExtendsComposerRemoteFilesystem()
     {
         $this->assertInstanceOf(
             'Composer\Util\RemoteFilesystem',
-            new RemoteFilesystem('', $this->io, $this->config)
+            new RemoteFilesystem('', $this->io)
         );
     }
 
+    // Inspired by testCopy of Composer
     public function testCopyUsesAcfFileUrl()
     {
-        $acfFileUrl = 'acfFileUrl';
+        $acfFileUrl = 'file://'.__FILE__;
+        $rfs = new RemoteFilesystem($acfFileUrl, $this->io);
+        $file = tempnam(sys_get_temp_dir(), 'pb');
 
-        // Expect an Exception
-        $this->setExpectedException(
-            'Composer\Downloader\TransportException',
-            $acfFileUrl
+        $this->assertTrue(
+            $rfs->copy('http://example.org', 'does-not-exist', $file)
         );
-
-        $rfs = new RemoteFilesystem($acfFileUrl, $this->io, $this->config);
-        $rfs->copy('orginUrl', 'fileUrl', 'fileName');
+        $this->assertFileExists($file);
+        unlink($file);
     }
 }