How to force a curl request in a PHP method to fail for a unit test

Question

I'm covering some legacy code with unit tests. I have some code that looks like this ^† (I have removed the bits not relevant to this question):

    public function search($query) {
        $query = urlencode($query);
        $url = 'https://example.com/search.php?q=' . $query;

        $curl = curl_init();
        curl_setopt_array($curl, array(
            CURLOPT_RETURNTRANSFER => 1,
            CURLOPT_URL => $url,
        ));
        $data = curl_exec($curl);

        if (!$data) {
            throw new Exception('An error occurred while trying to process the request.');
        }
    }

How can I force the curl request to fail so that the Exception gets throw n? I'm not allowed to change the existing code in a method until it is fully covered. The URL is hard-coded except for the query string, so I can't change that and the query string is correctly URL encoded with urlencode() , so I can't pass through a badly formatted string.

Is there a safe string length I could exceed for the query? Perhaps a setting I could change with ini_set() ?

_{^{† I'm aware of the bugs in the code}}

Answer 1

cURL favours couple of environmental variables for establishing communications and they can be used to affect curl operation without tweaking tested php code.

These variables are:

• http_proxy
• https_proxy
• no_proxy

So you can preserve the current values of those variables in setUp() and restore them in tearDown() .

Following code will break your curl for sure:

putenv("https_proxy=localhost:5678");
putenv("no_proxy=blah-blah-blah");