httpmock

This library builds on Go's built-in httptest library, adding a more mockable interface that can be used easily with other mocking tools like testify/mock. It does this by providing a Handler that receives HTTP components as separate arguments rather than a single *http.Request object.

Where the typical http.Handler interface is:

type Handler interface {
	ServeHTTP(ResponseWriter, *Request)
}

This library provides a server with the following interface, which works naturally with mocking libraries:

// Handler is the interface used by httpmock instead of http.Handler so that it can be mocked very easily.
type Handler interface {
	Handle(method, path string, body []byte) Response
}

Examples

The most primitive example, the OKHandler, just returns 200 OK to everything.

s := httpmock.NewServer(&httpmock.OKHandler{})
defer s.Close()

// Make any requests you want to s.URL(), using it as the mock downstream server

This example uses MockHandler, a Handler that is a testify/mock object.

downstream := httpmock.NewMockHandler(t)

// A simple GET that returns some pre-canned content
downstream.On("Handle", "GET", "/object/12345", mock.Anything).Return(httpmock.Response{
    Body: []byte(`{"status": "ok"}`),
})

s := httpmock.NewServer(downstream)
defer s.Close()

//
// Make any requests you want to s.URL(), using it as the mock downstream server
//

downstream.AssertExpectations(t)

If instead you wish to match against headers as well, a slightly different httpmock object can be used (please note the change in function name to be matched against):

downstream := &httpmock.NewMockHandlerWithHeaders(t)

// A simple GET that returns some pre-canned content and expects a specific header.
// Use MultiHeaderMatcher for multiple headers.
downstream.On("HandleWithHeaders", "GET", "/object/12345", HeaderMatcher("MOCK", "this"), mock.Anything).Return(httpmock.Response{
    Body: []byte(`{"status": "ok"}`),
})

// ... same as above

The httpmock package also provides helpers for checking calls using json objects, like so:

// This tests a hypothetical "echo" endpoint, which returns the body we pass to it.
type Obj struct {
    A string `json:"a"`
}

o := &Obj{A: "aye"}

// JSONMatcher ensures that this mock is triggered only when the HTTP body, when deserialized, matches the given
// object. Here, this mock response will get triggered only if `{"a":"aye"}` is sent.
downstream.On("Handle", "POST", "/echo", httpmock.JSONMatcher(o)).Return(httpmock.Response{
    Body: httpmock.ToJSON(o),
})