public function testHasFields()
{
$b = new PostBody();
$b->setField('foo', 'bar');
$b->setField('baz', '123');
$this->assertEquals('bar', $b->getField('foo'));
$this->assertEquals('123', $b->getField('baz'));
$this->assertNull($b->getField('ahh'));
$this->assertTrue($b->hasField('foo'));
$this->assertFalse($b->hasField('test'));
$b->replaceFields(['abc' => '123']);
$this->assertFalse($b->hasField('foo'));
$this->assertTrue($b->hasField('abc'));
}