PhlyTest\Http\MessageTraitTest::testAddHeaderAppendsToExistingHeader PHP Метод

    public function testAddHeaderAppendsToExistingHeader()
    {
        $message = $this->message->withHeader('X-Foo', 'Foo');
        $this->assertNotSame($this->message, $message);
        $message2 = $message->withAddedHeader('X-Foo', 'Bar');
        $this->assertNotSame($message, $message2);
        $this->assertEquals('Foo,Bar', $message2->getHeaderLine('X-Foo'));
    }