HTTPRegistry

HTTPRegistry is a tiny package designed to simplifying building configurable httptest servers. httptest is an incredibly powerful package that can be used to test the behavior of code that makes http calls. Unfortunately when the chain of calls to be tested is complex, setting up a mock server gets complicated and full of boilerplate test. This library is defined to take care of the boilerplate and let you focus on what matters in your tests.

Basic concepts

In a nutshell this library allows you to create a registry on which responses to requests can be registered. Then this registry can be used to instantiate a httptest server that can respond to http requests. The library then takes care of checking that all the responses are used and that not too many calls happen.

package main

import (
	"net/http"
	"testing"

	"github.com/dfioravanti/httpregistry"
)

func TestHttpRegistryWorks(t *testing.T) {
    // 1. Create the registry and defer the check that all responses
    //    that we will create are used.
    //    t is used to fail the test if the deferred check fails.
	registry := httpregistry.NewRegistry(t)
	defer registry.CheckAllResponsesAreConsumed()

    // 2. Add request to the registry
	registry.AddMethodAndURL(http.MethodGet, "/users")

    // 3. Create the server
	server := registry.GetServer()
	defer server.Close()

    // 4. Make calls, since we registered a single call then if we would call "/users" again it would fail
	response, err := http.Get(server.URL + "/users")
	if err != nil {
		t.Errorf("executing request failed: %v", err)
	}
	if response.StatusCode != 200 {
		t.Errorf("unexpected status code %v", response.StatusCode)
	}
}

Requests/Responses

The library provides various helper functions to make the process of attaching a response to a request easier. In the most general form it uses two types

• Request that defines the expected response to match
• Response that defines the response to be returned if a match happens

a request can be matched via the following

• A (method, exact path) combination, like GET /users
• A (method, regex) combination, like GET /users/*

plus additionally other constrains can be places on the matching

• It can be requested the request contains some headers like Accept: text/html.

Once a request is matched the corresponding Response is used to determine what the server should return. Currently the library allows to set

• Status code
• Body
• Headers

How is a request selected

In case multiple requests match the incoming one then the first one, by order of registration, matching that still has unconsumed responses will be selected. So for example

package main

import (
	"net/http"
	"testing"

	"github.com/dfioravanti/httpregistry"
)

func TestMultipleMatchingWorks(t *testing.T) {
	// 1. Create the registry and defer the check that all responses
	//    that we will create are used.
	//    t is used to fail the test if the deferred check fails.
	registry := httpregistry.NewRegistry(t)
	defer registry.CheckAllResponsesAreConsumed()

	// 2. Add requests to the registry
	registry.AddMethodAndURLWithStatusCode(
        http.MethodGet, "/users", http.StatusOK,
    )
	registry.AddMethodAndURLWithStatusCode(
        http.MethodGet, "/users", http.StatusNotFound,
    )

	// 3. Create the server
	server := registry.GetServer()
	defer server.Close()

	// 4. Make calls
	response, err := http.Get(server.URL + "/users")
	if err != nil {
		t.Errorf("executing request failed: %v", err)
	}
	if response.StatusCode != 200 {
		t.Errorf("unexpected status code %v", response.StatusCode)
	}

	response, err = http.Get(server.URL + "/users")
	if err != nil {
		t.Errorf("executing request failed: %v", err)
	}
	if response.StatusCode != 404 {
		t.Errorf("unexpected status code %v", response.StatusCode)
	}
}