github.com/jarcoal/httpmock

httpmock

Easy mocking of http responses from external resources.

Install

Currently supports Go 1.16 to 1.24 and is regularly tested against tip.

v1 branch has to be used instead of master.

In your go files, simply use:

import "github.com/jarcoal/httpmock"

Then next go mod tidy or go test invocation will automatically populate your go.mod with the latest httpmock release, now .

Usage

Simple Example:

func TestFetchArticles(t *testing.T) {
  httpmock.Activate(t)

  // Exact URL match
  httpmock.RegisterResponder("GET", "https://api.mybiz.com/articles",
    httpmock.NewStringResponder(200, `[{"id": 1, "name": "My Great Article"}]`))

  // Regexp match (could use httpmock.RegisterRegexpResponder instead)
  httpmock.RegisterResponder("GET", `=~^https://api\.mybiz\.com/articles/id/\d+\z`,
    httpmock.NewStringResponder(200, `{"id": 1, "name": "My Great Article"}`))

  // do stuff that makes a request to articles
  ...

  // get count info
  httpmock.GetTotalCallCount()

  // get the amount of calls for the registered responder
  info := httpmock.GetCallCountInfo()
  info["GET https://api.mybiz.com/articles"] // number of GET calls made to https://api.mybiz.com/articles
  info["GET https://api.mybiz.com/articles/id/12"] // number of GET calls made to https://api.mybiz.com/articles/id/12
  info[`GET =~^https://api\.mybiz\.com/articles/id/\d+\z`] // number of GET calls made to https://api.mybiz.com/articles/id/<any-number>
}

Advanced Example:

func TestFetchArticles(t *testing.T) {
  httpmock.Activate(t)

  // our database of articles
  articles := make([]map[string]interface{}, 0)

  // mock to list out the articles
  httpmock.RegisterResponder("GET", "https://api.mybiz.com/articles",
    func(req *http.Request) (*http.Response, error) {
      resp, err := httpmock.NewJsonResponse(200, articles)
      if err != nil {
        return httpmock.NewStringResponse(500, ""), nil
      }
      return resp, nil
    })

  // return an article related to the request with the help of regexp submatch (\d+)
  httpmock.RegisterResponder("GET", `=~^https://api\.mybiz\.com/articles/id/(\d+)\z`,
    func(req *http.Request) (*http.Response, error) {
      // Get ID from request
      id := httpmock.MustGetSubmatchAsUint(req, 1) // 1=first regexp submatch
      return httpmock.NewJsonResponse(200, map[string]interface{}{
        "id":   id,
        "name": "My Great Article",
      })
    })

  // mock to add a new article
  httpmock.RegisterResponder("POST", "https://api.mybiz.com/articles",
    func(req *http.Request) (*http.Response, error) {
      article := make(map[string]interface{})
      if err := json.NewDecoder(req.Body).Decode(&article); err != nil {
        return httpmock.NewStringResponse(400, ""), nil
      }

      articles = append(articles, article)

      resp, err := httpmock.NewJsonResponse(200, article)
      if err != nil {
        return httpmock.NewStringResponse(500, ""), nil
      }
      return resp, nil
    })

  // mock to add a specific article, send a Bad Request response
  // when the request body contains `"type":"toy"`
  httpmock.RegisterMatcherResponder("POST", "https://api.mybiz.com/articles",
    httpmock.BodyContainsString(`"type":"toy"`),
    httpmock.NewStringResponder(400, `{"reason":"Invalid article type"}`))

  // do stuff that adds and checks articles
}

Algorithm

When GET http://example.tld/some/path?b=12&a=foo&a=bar request is caught, all standard responders are checked against the following URL or paths, the first match stops the search:

• http://example.tld/some/path?b=12&a=foo&a=bar (original URL)
• http://example.tld/some/path?a=bar&a=foo&b=12 (sorted query params)
• http://example.tld/some/path (without query params)
• /some/path?b=12&a=foo&a=bar (original URL without scheme and host)
• /some/path?a=bar&a=foo&b=12 (same, but sorted query params)
• /some/path (path only)

If no standard responder matched, the regexp responders are checked, in the same order, the first match stops the search.

go-testdeep + tdsuite example:

// article_test.go

import (
  "testing"

  "github.com/jarcoal/httpmock"
  "github.com/maxatome/go-testdeep/helpers/tdsuite"
  "github.com/maxatome/go-testdeep/td"
)

type MySuite struct{}

func (s *MySuite) Setup(t *td.T) error {
  // block all HTTP requests
  httpmock.Activate(t)
  return nil
}

func (s *MySuite) PostTest(t *td.T, testName string) error {
  // remove any mocks after each test
  httpmock.Reset()
  return nil
}

func TestMySuite(t *testing.T) {
  tdsuite.Run(t, &MySuite{})
}

func (s *MySuite) TestArticles(assert, require *td.T) {
  httpmock.RegisterResponder("GET", "https://api.mybiz.com/articles.json",
    httpmock.NewStringResponder(200, `[{"id": 1, "name": "My Great Article"}]`))

  // do stuff that makes a request to articles.json
}

Ginkgo example:

// article_suite_test.go

import (
  // ...
  "github.com/jarcoal/httpmock"
)
// ...
var _ = BeforeSuite(func() {
  // block all HTTP requests
  httpmock.Activate()
})

var _ = BeforeEach(func() {
  // remove any mocks
  httpmock.Reset()
})

var _ = AfterSuite(func() {
  httpmock.DeactivateAndReset()
})


// article_test.go

import (
  // ...
  "github.com/jarcoal/httpmock"
)

var _ = Describe("Articles", func() {
  It("returns a list of articles", func() {
    httpmock.RegisterResponder("GET", "https://api.mybiz.com/articles.json",
      httpmock.NewStringResponder(200, `[{"id": 1, "name": "My Great Article"}]`))

    // do stuff that makes a request to articles.json
  })
})

Ginkgo + Resty Example:

// article_suite_test.go

import (
  // ...
  "github.com/jarcoal/httpmock"
  "github.com/go-resty/resty/v2"
)
// ...

// global client (using resty.New() creates a new transport each time,
// so you need to use the same one here and when making the request)
var client = resty.New()

var _ = BeforeSuite(func() {
  // block all HTTP requests
  httpmock.ActivateNonDefault(client.GetClient())
})

var _ = BeforeEach(func() {
  // remove any mocks
  httpmock.Reset()
})

var _ = AfterSuite(func() {
  httpmock.DeactivateAndReset()
})


// article_test.go

import (
  // ...
  "github.com/jarcoal/httpmock"
)

type Article struct {
	Status struct {
		Message string `json:"message"`
		Code    int    `json:"code"`
	} `json:"status"`
}

var _ = Describe("Articles", func() {
  It("returns a list of articles", func() {
    fixture := `{"status":{"message": "Your message", "code": 200}}`
    // have to use NewJsonResponder to get an application/json content-type
    // alternatively, create a go object instead of using json.RawMessage
    responder, _ := httpmock.NewJsonResponder(200, json.RawMessage(`{"status":{"message": "Your message", "code": 200}}`)
    fakeUrl := "https://api.mybiz.com/articles.json"
    httpmock.RegisterResponder("GET", fakeUrl, responder)

    // fetch the article into struct
    articleObject := &Article{}
    _, err := resty.R().SetResult(articleObject).Get(fakeUrl)

    // do stuff with the article object ...
  })
})