Constructor chaining giving method not defined

Question

I have the following class with constructor chaining , but the validations are returning Method not found or incorrect signature

class

@IsTest
global class CalloutMock implements HttpCalloutMock {
    private Map<String,HttpResponse> httpResponseMap = new Map<String,HttpResponse>();

   global CalloutMock(Map<String,HttpResponse> responseMap){
        if (responseMap != null) {
            httpResponseMap = responseMap;
        }
    }

   global CalloutMock(){
        CalloutMock(null);
    }

    global HttpResponse respond(HttpRequest req) {
        System.debug('req end point hitting is ' + req.getEndpoint());
        return  httpResponseMap.get(req.getEndpoint());
  
    }

}

why is that ? and how do i resolve it?

Answer 1

To call a different constructor, you should call this(null);, instead CalloutMock(null);. The latter would just call an instance method called CalloutMock, which is not exactly what you're doing.