测试HTTP请求时出现Nil解除引用错误

Question

I am trying to test a HTTP request in my Go library. Object which makes the call accepts a HTTP client object via dependency injection so in my test I am mocking the HTTP client like this:

func TestMyObject(t *testing.T) {
    server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        w.WriteHeader(200)
        w.Header().Set("Content-Type", "application/json")
        fmt.Fprintln(w, mockJSONResponse)
    }))
    defer server.Close()

    // Make a transport that reroutes all traffic to the example server
    transport := &http.Transport{
        Proxy: func(req *http.Request) (*url.URL, error) {
            return url.Parse(server.URL)
        },
    }

    // Make a http.Client with the transport
    httpClient := &http.Client{Transport: transport}

    // I am passing the httpClient to my object
}

Here is how the HTTP request is made within my object:

// Make - makes a prepared HTTP request
func (ir *MyObject) Make() *http.Response {
    if ir.Err != nil {
        return nil
    }

    ir.resp, ir.Err = ir.Client.Do(ir.req)

    runtime.SetFinalizer(ir, func(ir *MyObject) {
        ir.resp.Body.Close()
    })

    ir.logReqRes()
    ir.checkErrorResponse()

    return ir.resp
}

I am getting nil pointer dereference error though:

panic: runtime error: invalid memory address or nil pointer dereference [recovered]
panic: runtime error: invalid memory address or nil pointer dereference

In this function (I am trying to log the response):

// Logs request and response
func (ir *MyObject) logReqRes() {
    log.Print("AAAAAAA")
    log.Print(ir.resp)
    log.Print("AAAAAAA")
    if reqInfo, err := httputil.DumpRequest(ir.req, true); err == nil {
        log.Print("Logging request:")
        log.Print(string(reqInfo))
    }
    if respInfo, err := httputil.DumpResponse(ir.resp, true); err == nil {
        log.Print("Logging response:")
        log.Print(string(respInfo))
    }
}

As you can see, ir.resp is nil for some reason. Any ideas?

Answer 1

Ok. I found an issue. Better logging of errors actually showed that my mistake was very simple.

I was passing this as a URL to mocked HTTP client:

host/api/v1/tokens/

Which was resulting in this error:

Post host/api/v1/tokens/: unsupported protocol scheme

Apparently the URL must include a proper HTTP scheme (http://) even when you are using a test server.