gock

Versatile HTTP mocking made easy in Go.

Heavily inspired by nock. See also its Python port, pook.

To get started, take a look to the examples.

Features

Simple, expressive, fluent API.
Semantic API DSL for declarative HTTP mock declarations.
Built-in helpers for easy JSON/XML mocking.
Supports persistent and volatile TTL-limited mocks.
Full regular expressions capable HTTP request mock matching.
Designed for both testing and runtime scenarios.
Match request by method, URL params, headers and bodies.
Extensible and pluggable HTTP matching rules.
Ability to switch between mock and real networking modes.
Ability to filter/map HTTP requests for accurate mock matching.
Supports map and filters to handle mocks easily.
Wide compatible HTTP interceptor using http.RoundTripper interface.
Works with any net/http compatible client, such as gentleman.
Network delay simulation (beta).
Extensible and hackable API.
Dependency free.

Installation

go get -u gopkg.in/h2non/gock.v1

API

See godoc reference for detailed API documentation.

How it mocks

Intercepts any HTTP outgoing request via http.DefaultTransport or custom http.Transport used by any http.Client.
Matches outgoing HTTP requests against a pool of defined HTTP mock expectations in FIFO declaration order.
If at least one mock matches, it will be used in order to compose the mock HTTP response.
If no mock can be matched, it will resolve the request with an error, unless real networking mode is enable, in which case a real HTTP request will be performed.

Tips

Testing

Declare your mocks before you start declaring the concrete test logic:

func TestFoo(t *testing.T) {
  defer gock.Off() // Flush pending mocks after test execution

  gock.New("http://server.com").
    Get("/bar").
    Reply(200).
    JSON(map[string]string{"foo": "bar"})

  // Your test code starts here...
}

Race conditions

If you're running concurrent code, be aware that your mocks are declared first to avoid unexpected race conditions while configuring gock or intercepting custom HTTP clients.

gock is not fully thread-safe, but sensible parts are. Any help making gock more reliable in this sense is appreciated.

Define complex mocks first

If you're mocking a bunch of mocks in the same test suite, it's recommended to define the more concrete mocks first, and then the generic ones.

This approach usually avoids matching unexpected generic mocks (e.g: specific header, body payload...) instead of the generic ones that performs less complex matches.

Disable `gock` traffic interception once done

In other to minimize potential side effects within your test code, it's a good practice disabling gock once you are done with your HTTP testing logic.

A Go idiomatic approach for doing this can be using it in a defer statement, such as:

function TestGock (t *testing.T) {
	defer gock.Off()

	// ... my test code goes here
}

Intercept an `http.Client` just once

You don't need to intercept multiple times the same http.Client instance.

Just call gock.InterceptClient(client) once, typically at the beginning of your test scenarios.

Restore an `http.Client` after interception

NOTE: this is not required is you are using http.DefaultClient or http.DefaultTransport.

As a good testing pattern, you should call gock.RestoreClient(client) after running your test scenario, typically as after clean up hook.

You can also use a defer statement for doing it, as you do with gock.Off(), such as:

function TestGock (t *testing.T) {
	defer gock.Off()
	defer gock.RestoreClient(client)

	// ... my test code goes here
}

Examples

See examples directory for more featured use cases.

Simple mocking via tests

package test

import (
  "github.com/nbio/st"
  "gopkg.in/h2non/gock.v1"
  "io/ioutil"
  "net/http"
  "testing"
)

func TestSimple(t *testing.T) {
  defer gock.Off()

  gock.New("http://foo.com").
    Get("/bar").
    Reply(200).
    JSON(map[string]string{"foo": "bar"})

  res, err := http.Get("http://foo.com/bar")
  st.Expect(t, err, nil)
  st.Expect(t, res.StatusCode, 200)

  body, _ := ioutil.ReadAll(res.Body)
  st.Expect(t, string(body)[:13], `{"foo":"bar"}`)

  // Verify that we don't have pending mocks
  st.Expect(t, gock.IsDone(), true)
}

Request headers matching

package test

import (
  "github.com/nbio/st"
  "gopkg.in/h2non/gock.v1"
  "io/ioutil"
  "net/http"
  "testing"
)

func TestMatchHeaders(t *testing.T) {
  defer gock.Off()

  gock.New("http://foo.com").
    MatchHeader("Authorization", "^foo bar$").
    MatchHeader("API", "1.[0-9]+").
    HeaderPresent("Accept").
    Reply(200).
    BodyString("foo foo")

  req, err := http.NewRequest("GET", "http://foo.com", nil)
  req.Header.Set("Authorization", "foo bar")
  req.Header.Set("API", "1.0")
  req.Header.Set("Accept", "text/plain")

  res, err := (&http.Client{}).Do(req)
  st.Expect(t, err, nil)
  st.Expect(t, res.StatusCode, 200)
  body, _ := ioutil.ReadAll(res.Body)
  st.Expect(t, string(body), "foo foo")

  // Verify that we don't have pending mocks
  st.Expect(t, gock.IsDone(), true)
}

JSON body matching and response

package test

import (
  "bytes"
  "github.com/nbio/st"
  "gopkg.in/h2non/gock.v1"
  "io/ioutil"
  "net/http"
  "testing"
)

func TestMockSimple(t *testing.T) {
  defer gock.Off()

  gock.New("http://foo.com").
    Post("/bar").
    MatchType("json").
    JSON(map[string]string{"foo": "bar"}).
    Reply(201).
    JSON(map[string]string{"bar": "foo"})

  body := bytes.NewBuffer([]byte(`{"foo":"bar"}`))
  res, err := http.Post("http://foo.com/bar", "application/json", body)
  st.Expect(t, err, nil)
  st.Expect(t, res.StatusCode, 201)

  resBody, _ := ioutil.ReadAll(res.Body)
  st.Expect(t, string(resBody)[:13], `{"bar":"foo"}`)

  // Verify that we don't have pending mocks
  st.Expect(t, gock.IsDone(), true)
}

Mocking a custom http.Client and http.RoundTripper

package test

import (
  "github.com/nbio/st"
  "gopkg.in/h2non/gock.v1"
  "io/ioutil"
  "net/http"
  "testing"
)

func TestClient(t *testing.T) {
  defer gock.Off()

  gock.New("http://foo.com").
    Reply(200).
    BodyString("foo foo")

  req, err := http.NewRequest("GET", "http://foo.com", nil)
  client := &http.Client{Transport: &http.Transport{}}
  gock.InterceptClient(client)

  res, err := client.Do(req)
  st.Expect(t, err, nil)
  st.Expect(t, res.StatusCode, 200)
  body, _ := ioutil.ReadAll(res.Body)
  st.Expect(t, string(body), "foo foo")

  // Verify that we don't have pending mocks
  st.Expect(t, gock.IsDone(), true)
}

Enable real networking

package main

import (
  "fmt"
  "gopkg.in/h2non/gock.v1"
  "io/ioutil"
  "net/http"
)

func main() {
  defer gock.Off()
  defer gock.DisableNetworking()

  gock.EnableNetworking()
  gock.New("http://httpbin.org").
    Get("/get").
    Reply(201).
    SetHeader("Server", "gock")

  res, err := http.Get("http://httpbin.org/get")
  if err != nil {
    fmt.Errorf("Error: %s", err)
  }

  // The response status comes from the mock
  fmt.Printf("Status: %d\n", res.StatusCode)
  // The server header comes from mock as well
  fmt.Printf("Server header: %s\n", res.Header.Get("Server"))
  // Response body is the original
  body, _ := ioutil.ReadAll(res.Body)
  fmt.Printf("Body: %s", string(body))

  // Verify that we don't have pending mocks
  st.Expect(t, gock.IsDone(), true)
}

Debug intercepted http requests

package main

import (
	"bytes"
	"gopkg.in/h2non/gock.v1"
	"net/http"
)

func main() {
	defer gock.Off()
	gock.Observe(gock.DumpRequest)

	gock.New("http://foo.com").
		Post("/bar").
		MatchType("json").
		JSON(map[string]string{"foo": "bar"}).
		Reply(200)

	body := bytes.NewBuffer([]byte(`{"foo":"bar"}`))
	http.Post("http://foo.com/bar", "application/json", body)
}

Hacking it!

You can easily hack gock defining custom matcher functions with own matching rules.

See add matcher functions and custom matching layer examples for further details.

License

MIT - Tomas Aparicio

elliotwms/gock