Author: Iván Montes (drslump@pollinimini.net)
Author: Fabio B. Silva (fabio.bat.silva@gmail.com)
Inheritance: implements Protobuf\Binary\Platform\NegativeEncoder
 public function testEncodeSFixed64()
 {
     $encoder = new BcNegativeEncoder();
     $bytes = $encoder->encodeSFixed64(-123456789123456789);
     $expected = [1 => 41195, 2 => 21295, 3 => 25780, 4 => 65097];
     $this->assertEquals($expected, unpack('v*', $bytes));
 }