empire/go-httpmock

Proof of concept to mock go http server

httpmock

Versatile HTTP mocking made easy in Go that works with any net/http based stdlib implementation.

Heavily inspired by gock. There is 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.
• Works with any net/http compatible client, such as gentleman.
• Network timeout/cancelation delay simulation.
• Extensible and hackable API.
• Dependency free.

Installation

go get -u github.com/empire/go-httpmock

API

See godoc reference for detailed API documentation.

How it mocks (TODO refine the following items)

1. Intercepts any HTTP outgoing request via http.DefaultTransport or custom http.Transport used by any http.Client.
2. Matches outgoing HTTP requests against a pool of defined HTTP mock expectations in FIFO declaration order.
3. If at least one mock matches, it will be used in order to compose the mock HTTP response.
4. 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) {
  s := httpmock.Server()

  httpmock.New(s.URL).
    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 httpmock or intercepting custom HTTP clients.

httpmock is not fully thread-safe, but sensible parts are. Any help making httpmock 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.

Examples

See examples directory for more featured use cases.

Simple mocking via tests

package test

import (
  "io/ioutil"
  "net/http"
  "testing"

  "github.com/empire/go-httpmock"
  "github.com/stretchr/testify/require"
)

func TestSimple(t *testing.T) {
  s := httpmock.Server(t)
  httpmock.New(s.URL).
    Get("/bar").
    Reply(200).
    JSON(map[string]string{"foo": "bar"})

  res, err := http.Get(s.URL + "/bar")
  require.Equal(t, err, nil)
  require.Equal(t, res.StatusCode, 200)

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

  // Verify that we don't have pending mocks
  require.True(t, httpmock.IsDone(t))
}

Request headers matching

package test

import (
  "io/ioutil"
  "net/http"
  "testing"

  "github.com/empire/go-httpmock"
  "github.com/stretchr/testify/require"
)

func TestMatchHeaders(t *testing.T) {
  s := httpmock.Server(t)

  httpmock.New(s.URL).
    MatchHeader("Authorization", "^foo bar$").
    MatchHeader("API", "1.[0-9]+").
    HeaderPresent("Accept").
    Reply(200).
    BodyString("foo foo")

  req, err := http.NewRequest("GET", s.URL, 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)
  require.Equal(t, err, nil)
  require.Equal(t, res.StatusCode, 200)
  body, _ := ioutil.ReadAll(res.Body)
  require.Equal(t, string(body), "foo foo")

  // Verify that we don't have pending mocks
  require.True(t, httpmock.IsDone(t))
}

Request param matching

package test

import (
  "io/ioutil"
  "net/http"
  "testing"

  "github.com/empire/go-httpmock"
  "github.com/stretchr/testify/require"
)

func TestMatchParams(t *testing.T) {
  s := httpmock.Server(t)
  httpmock.New(s.URL).
    MatchParam("page", "1").
    MatchParam("per_page", "10").
    Reply(200).
    BodyString("foo foo")

  req, err := http.NewRequest("GET", s.URL+"?page=1&per_page=10", nil)

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

  // Verify that we don't have pending mocks
  require.True(t, httpmock.IsDone(t))
}

JSON body matching and response

package test

import (
  "bytes"
  "io/ioutil"
  "net/http"
  "testing"

  "github.com/empire/go-httpmock"
  "github.com/stretchr/testify/require"
)

func TestMockSimple(t *testing.T) {
  s := httpmock.Server(t)
  httpmock.New(s.URL).
    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(s.URL+"/bar", "application/json", body)
  require.Equal(t, err, nil)
  require.Equal(t, res.StatusCode, 201)

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

  // Verify that we don't have pending mocks
  require.True(t, httpmock.IsDone(t))
}

Mocking a custom http.Client and http.RoundTripper

package test

import (
  "io/ioutil"
  "net/http"
  "testing"

  "github.com/empire/go-httpmock"
  "github.com/stretchr/testify/require"
)

func TestClient(t *testing.T) {
  s := httpmock.Server(t)
  httpmock.New(s.URL).
    Reply(200).
    BodyString("foo foo")

  req, err := http.NewRequest("GET", s.URL, nil)
  client := &http.Client{Transport: &http.Transport{}}

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

  // Verify that we don't have pending mocks
  require.True(t, httpmock.IsDone(t))
}

Debug intercepted http requests

// TODO check the following example code
package main

import (
  "bytes"
  "github.com/empire/go-httpmock"
  "net/http"
)

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

  httpmock.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 httpmock defining custom matcher functions with own matching rules.

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

License

MIT - Tomas Aparicio