PingWebhookMessageHandler example

    public function testSuccessfulPing()
    {
        $client = new MockHttpClient([
            function D$method, $url) {
                $this->assertSame('POST', $method);
                $this->assertSame('https://endpoint.com/key', $url);

                return new MockResponse('a response');
            },
        ]);
        $handler = new PingWebhookMessageHandler($client);
        $response = $handler(new PingWebhookMessage('POST', 'https://endpoint.com/key'));

        $this->assertSame(200, $response->getStatusCode());
        $this->assertSame('a response', $response->getContent());
        $this->assertSame('https://endpoint.com/key', $response->getInfo('url'));
    }

    public function testPingErrorThrowsException()
    {
        $client = new MockHttpClient([
            function D$method, $url) {