Hii developers.
I'm using google v2 captcha on my vf extensions class
Now problem is I'm not able to test the captcha

this is the extension coce

public class addContactExtension {

    @TestVisible private static String baseUrl = 'https://www.google.com/recaptcha/api/siteverify';//captcha API endpoint.
    @TestVisible private static String secret = '6LcaHdMAEqDE4TTL****';//captcha API secret key.

    public String sitekey { //Captcha site key
        get {
            return '6LcaHdMUAAAAAKNwNDoR0RD8SXffM3JlwBSGKy6p';//Here, use my site key.
        }set;
	}
    
    public String response  {
        get {
            return ApexPages.currentPage().getParameters().get('g-recaptcha-response');
        }set;
    }
    
   Public pageReference paymentSave(){

        String responseBody = makeRequest(baseUrl,'secret=' + secret +'&response='+ response);
        String success = getValueFromJson(responseBody, 'success');
        if(success.equalsIgnoreCase('true')) {
           //execute code.
         }
}

TestVisible private static String makeRequest(string url, string body) { //Captcha api request start here
        HttpResponse response = null;
        HttpRequest req = new HttpRequest();
        req.setEndpoint(url);
        req.setMethod('POST');
        req.setBody (body);
        try{
            Http http = new Http();
            response = http.send(req);
            return response.getBody();
        }catch(System.Exception e) {
            //System.debug('ERROR: ' + e);
        }
        return '{"success":false}';
    }//Captcha api request Ends here


    public static string getValueFromJson ( String strJson, String field ) {
        JSONParser parser = JSON.createParser(strJson);
        while (parser.nextToken() != null){
            if ((parser.getCurrentToken() == JSONToken.FIELD_NAME)) {
                if(parser.getText() == field){
                    // Get the value.
                    parser.nextToken();
                    return parser.getText();
                }
            }
        }
        return null;
    }

}

How to test this method .
Somebody please help