public function test()
{
$raw = ['foo' => 'foo', 'foo-bar' => 'foo-bar'];
$headers = new Headers($raw);
$this->assertSame(['Foo' => 'foo', 'Foo-Bar' => 'foo-bar'], $headers->toArray());
$this->assertTrue($headers->has('foo'));
$this->assertTrue($headers->has('Foo'));
$this->assertFalse($headers->has('bar'));
$this->assertSame('foo', $headers->get('Foo'));
$headers->remove('Foo');
$this->assertFalse($headers->has('foo'));
$this->assertSame('Foo-Bar: foo-bar', $headers->getLine('foo-bar'));
$this->assertSame(['Foo-Bar: foo-bar'], $headers->getLines());
$this->assertSame('Foo-Bar: foo-bar', $headers->toString());
$this->assertNull($headers->getLine('non-existing'));
}