Testing HTTP Servers with Live Requests in Go

Unit testing handlers in isolation is essential, but can overlook the effects of routing and other middleware. For a comprehensive test, consider using a "live server" approach.

Live Server Testing with httptest.Server

The net/http/httptest.Server type facilitates live server testing. It creates a server using the provided handler (in this case, a Gorilla mux router). Here's an example:

func TestIndex(t *testing.T) {
  // Create server using the router initialized elsewhere.
  ts := httptest.NewServer(router)
  defer ts.Close()

  newreq := func(method, url string, body io.Reader) *http.Request {
    r, err := http.NewRequest(method, url, body)
    if err != nil {
        t.Fatal(err)
    }
    return r
  }

  tests := []struct {
    name string
    r    *http.Request
  }{
    // Test GET and POST requests.
    {name: "1: testing get", r: newreq("GET", ts.URL "/", nil)},
    {name: "2: testing post", r: newreq("POST", ts.URL "/", nil)}, // reader argument required for POST
  }
  for _, tt := range tests {
    t.Run(tt.name, func(t *testing.T) {
        resp, err := http.DefaultClient.Do(tt.r)
        defer resp.Body.Close()
        if err != nil {
            t.Fatal(err)
        }
        // check for expected response here.
    })
  }
}

Note that httptest.Server can be used to test any handler that satisfies the http.Handler interface, not just Gorilla mux.

Considerations

While live server testing provides a more realistic test, it can also be slower and more resource-intensive than unit testing. Consider a combination of unit and integration testing for a comprehensive testing strategy.