httpstub.go

package httpstub

import (
	"net/http"
	"net/http/httptest"
	"strings"
)

// Server is a configurable stub server.
type Server struct {
	URL string

	srv                *httptest.Server
	endpoints          []*Endpoint
	defaultContentType string
}

// New starts a new stub server.
func New() *Server {
	s := &Server{}
	ts := httptest.NewServer(s)
	s.srv = ts
	s.URL = ts.URL
	return s
}

// Close shuts down the server and releases the port it was listening on.
func (s *Server) Close() {
	s.srv.Close()
}

// Path creates an endpoint to respond to a request URL path. Paths can be static prefixes or may contain * to signify a path component wildcard, so /u/*/n matches /u/2/n.
func (s *Server) Path(p string) *Endpoint {
	e := &Endpoint{
		path:        p,
		contentType: s.defaultContentType,
	}
	s.endpoints = append(s.endpoints, e)
	return e
}

// WithDefaultContentType sets the default content type for the server. Evaluated when creating endpoints, so must be set first.
func (s *Server) WithDefaultContentType(t string) *Server {
	s.defaultContentType = t
	return s
}

// ServeHTTP sets *Server implement http.Handler.
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	for _, e := range s.endpoints {
		// find the first matching endpoint
		if !matches(r.URL.Path, e.path) {
			continue
		}

		e.ServeHTTP(w, r)
		return
	}
}

// matches checks the request path against an endpoint path prefix pattern, comparing each path component one by one, treating * as a wildcard
func matches(req, endp string) bool {
	pc := strings.Split(req, "/")
	ec := strings.Split(endp, "/")
	if len(ec) > len(pc) {
		return false
	}

	for i, c := range ec {
		if c == "*" {
			continue
		}
		if c != pc[i] {
			return false
		}
	}
	return true
}