Add RoundTripper method to ghttp.Server

docs/index.md

@@ -2424,6 +2424,33 @@ To bring it all together: there are three ways to instruct a `ghttp` server to h
 
 When a `ghttp` server receives a request it first checks against the set of handlers registered via `RouteToHandler` if there is no such handler it proceeds to pop an `AppendHandlers` handler off the stack, if the stack of ordered handlers is empty, it will check whether `GetAllowUnhandledRequests` returns `true` or `false`.  If `false` the test fails.  If `true`, a response is sent with whatever `GetUnhandledRequestStatusCode` returns.
 
+### Using a RoundTripper to route requests to the test Server
+
+So far you have seen examples of using `server.URL()` to get the string URL of the test server. This is ok if you are testing code where you can pass the URL. In some cases you might need to pass a `http.Client` or similar.
+
+You can use `server.RoundTripper(nil)` to create a `http.RoundTripper` which will redirect requests to the test server.
+
+The method takes another `http.RoundTripper` to make the request to the test server, this allows chaining `http.Transports` or otherwise.
+
+If passed `nil`, then `http.DefaultTransport` is used to make the request.
+
+```go
+Describe("The http client", func() {
+    var server *ghttp.Server
+    var httpClient *http.Client
+
+    BeforeEach(func() {
+        server = ghttp.NewServer()
+        httpClient = &http.Client{Transport: server.RoundTripper(nil)}
+    })
+
+    AfterEach(func() {
+        //shut down the server between tests
+        server.Close()
+    })
+})
+```
+
 ## `gbytes`: Testing Streaming Buffers
 
 `gbytes` implements `gbytes.Buffer` - an `io.WriteCloser` that captures all input to an in-memory buffer.

ghttp/test_server.go

@@ -186,26 +186,26 @@ type Server struct {
 	calls   int
 }
 
-//Start() starts an unstarted ghttp server.  It is a catastrophic error to call Start more than once (thanks, httptest).
+// Start() starts an unstarted ghttp server.  It is a catastrophic error to call Start more than once (thanks, httptest).
 func (s *Server) Start() {
 	s.HTTPTestServer.Start()
 }
 
-//URL() returns a url that will hit the server
+// URL() returns a url that will hit the server
 func (s *Server) URL() string {
 	s.rwMutex.RLock()
 	defer s.rwMutex.RUnlock()
 	return s.HTTPTestServer.URL
 }
 
-//Addr() returns the address on which the server is listening.
+// Addr() returns the address on which the server is listening.
 func (s *Server) Addr() string {
 	s.rwMutex.RLock()
 	defer s.rwMutex.RUnlock()
 	return s.HTTPTestServer.Listener.Addr().String()
 }
 
-//Close() should be called at the end of each test.  It spins down and cleans up the test server.
+// Close() should be called at the end of each test.  It spins down and cleans up the test server.
 func (s *Server) Close() {
 	s.rwMutex.Lock()
 	server := s.HTTPTestServer
@@ -217,14 +217,14 @@ func (s *Server) Close() {
 	}
 }
 
-//ServeHTTP() makes Server an http.Handler
-//When the server receives a request it handles the request in the following order:
+// ServeHTTP() makes Server an http.Handler
+// When the server receives a request it handles the request in the following order:
 //
-//1. If the request matches a handler registered with RouteToHandler, that handler is called.
-//2. Otherwise, if there are handlers registered via AppendHandlers, those handlers are called in order.
-//3. If all registered handlers have been called then:
-//   a) If AllowUnhandledRequests is set to true, the request will be handled with response code of UnhandledRequestStatusCode
-//   b) If AllowUnhandledRequests is false, the request will not be handled and the current test will be marked as failed.
+//  1. If the request matches a handler registered with RouteToHandler, that handler is called.
+//  2. Otherwise, if there are handlers registered via AppendHandlers, those handlers are called in order.
+//  3. If all registered handlers have been called then:
+//     a) If AllowUnhandledRequests is set to true, the request will be handled with response code of UnhandledRequestStatusCode
+//     b) If AllowUnhandledRequests is false, the request will not be handled and the current test will be marked as failed.
 func (s *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	s.rwMutex.Lock()
 	defer func() {
@@ -280,18 +280,18 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	}
 }
 
-//ReceivedRequests is an array containing all requests received by the server (both handled and unhandled requests)
+// ReceivedRequests is an array containing all requests received by the server (both handled and unhandled requests)
 func (s *Server) ReceivedRequests() []*http.Request {
 	s.rwMutex.RLock()
 	defer s.rwMutex.RUnlock()
 
 	return s.receivedRequests
 }
 
-//RouteToHandler can be used to register handlers that will always handle requests that match
-//the passed in method and path.
+// RouteToHandler can be used to register handlers that will always handle requests that match
+// the passed in method and path.
 //
-//The path may be either a string object or a *regexp.Regexp.
+// The path may be either a string object or a *regexp.Regexp.
 func (s *Server) RouteToHandler(method string, path interface{}, handler http.HandlerFunc) {
 	s.rwMutex.Lock()
 	defer s.rwMutex.Unlock()
@@ -337,25 +337,25 @@ func (s *Server) handlerForRoute(method string, path string) (http.HandlerFunc,
 	return nil, false
 }
 
-//AppendHandlers will appends http.HandlerFuncs to the server's list of registered handlers.  The first incoming request is handled by the first handler, the second by the second, etc...
+// AppendHandlers will appends http.HandlerFuncs to the server's list of registered handlers.  The first incoming request is handled by the first handler, the second by the second, etc...
 func (s *Server) AppendHandlers(handlers ...http.HandlerFunc) {
 	s.rwMutex.Lock()
 	defer s.rwMutex.Unlock()
 
 	s.requestHandlers = append(s.requestHandlers, handlers...)
 }
 
-//SetHandler overrides the registered handler at the passed in index with the passed in handler
-//This is useful, for example, when a server has been set up in a shared context, but must be tweaked
-//for a particular test.
+// SetHandler overrides the registered handler at the passed in index with the passed in handler
+// This is useful, for example, when a server has been set up in a shared context, but must be tweaked
+// for a particular test.
 func (s *Server) SetHandler(index int, handler http.HandlerFunc) {
 	s.rwMutex.Lock()
 	defer s.rwMutex.Unlock()
 
 	s.requestHandlers[index] = handler
 }
 
-//GetHandler returns the handler registered at the passed in index.
+// GetHandler returns the handler registered at the passed in index.
 func (s *Server) GetHandler(index int) http.HandlerFunc {
 	s.rwMutex.RLock()
 	defer s.rwMutex.RUnlock()
@@ -374,12 +374,12 @@ func (s *Server) Reset() {
 	s.routedHandlers = nil
 }
 
-//WrapHandler combines the passed in handler with the handler registered at the passed in index.
-//This is useful, for example, when a server has been set up in a shared context but must be tweaked
-//for a particular test.
+// WrapHandler combines the passed in handler with the handler registered at the passed in index.
+// This is useful, for example, when a server has been set up in a shared context but must be tweaked
+// for a particular test.
 //
-//If the currently registered handler is A, and the new passed in handler is B then
-//WrapHandler will generate a new handler that first calls A, then calls B, and assign it to index
+// If the currently registered handler is A, and the new passed in handler is B then
+// WrapHandler will generate a new handler that first calls A, then calls B, and assign it to index
 func (s *Server) WrapHandler(index int, handler http.HandlerFunc) {
 	existingHandler := s.GetHandler(index)
 	s.SetHandler(index, CombineHandlers(existingHandler, handler))
@@ -392,34 +392,55 @@ func (s *Server) CloseClientConnections() {
 	s.HTTPTestServer.CloseClientConnections()
 }
 
-//SetAllowUnhandledRequests enables the server to accept unhandled requests.
+// SetAllowUnhandledRequests enables the server to accept unhandled requests.
 func (s *Server) SetAllowUnhandledRequests(allowUnhandledRequests bool) {
 	s.rwMutex.Lock()
 	defer s.rwMutex.Unlock()
 
 	s.AllowUnhandledRequests = allowUnhandledRequests
 }
 
-//GetAllowUnhandledRequests returns true if the server accepts unhandled requests.
+// GetAllowUnhandledRequests returns true if the server accepts unhandled requests.
 func (s *Server) GetAllowUnhandledRequests() bool {
 	s.rwMutex.RLock()
 	defer s.rwMutex.RUnlock()
 
 	return s.AllowUnhandledRequests
 }
 
-//SetUnhandledRequestStatusCode status code to be returned when the server receives unhandled requests
+// SetUnhandledRequestStatusCode status code to be returned when the server receives unhandled requests
 func (s *Server) SetUnhandledRequestStatusCode(statusCode int) {
 	s.rwMutex.Lock()
 	defer s.rwMutex.Unlock()
 
 	s.UnhandledRequestStatusCode = statusCode
 }
 
-//GetUnhandledRequestStatusCode returns the current status code being returned for unhandled requests
+// GetUnhandledRequestStatusCode returns the current status code being returned for unhandled requests
 func (s *Server) GetUnhandledRequestStatusCode() int {
 	s.rwMutex.RLock()
 	defer s.rwMutex.RUnlock()
 
 	return s.UnhandledRequestStatusCode
 }
+
+// RoundTripper returns a RoundTripper which updates requests to point to the server.
+// This is useful when you want to use the server as a RoundTripper in an http.Client.
+// If rt is nil, http.DefaultTransport is used.
+func (s *Server) RoundTripper(rt http.RoundTripper) http.RoundTripper {
+	if rt == nil {
+		rt = http.DefaultTransport
+	}
+	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+		r.URL.Scheme = "http"
+		r.URL.Host = s.Addr()
+		return rt.RoundTrip(r)
+	})
+}
+
+// Helper type for creating a RoundTripper from a function
+type RoundTripperFunc func(*http.Request) (*http.Response, error)
+
+func (fn RoundTripperFunc) RoundTrip(r *http.Request) (*http.Response, error) {
+	return fn(r)
+}

ghttp/test_server_test.go

@@ -1190,4 +1190,63 @@ var _ = Describe("TestServer", func() {
 			})
 		})
 	})
+
+	Describe("RoundTripper", func() {
+		var called []string
+		BeforeEach(func() {
+			called = []string{}
+			s.RouteToHandler("GET", "/routed", func(w http.ResponseWriter, req *http.Request) {
+				called = append(called, "get")
+			})
+			s.RouteToHandler("POST", "/routed", func(w http.ResponseWriter, req *http.Request) {
+				called = append(called, "post")
+			})
+		})
+
+		It("should send http traffic to test server with default transport", func() {
+			client := http.Client{Transport: s.RoundTripper(nil)}
+			client.Get("http://example.com/routed")
+			client.Post("http://example.com/routed", "application/json", nil)
+			client.Get("http://foo.bar/routed")
+			client.Post("http://foo.bar/routed", "application/json", nil)
+			Expect(called).Should(Equal([]string{"get", "post", "get", "post"}))
+		})
+
+		It("should send https traffic to test server with default transport", func() {
+			client := http.Client{Transport: s.RoundTripper(nil)}
+			client.Get("https://example.com/routed")
+			client.Post("https://example.com/routed", "application/json", nil)
+			client.Get("https://foo.bar/routed")
+			client.Post("https://foo.bar/routed", "application/json", nil)
+			Expect(called).Should(Equal([]string{"get", "post", "get", "post"}))
+		})
+
+		It("should send http traffic to test server with default transport", func() {
+			transport := http.Transport{}
+			client := http.Client{Transport: s.RoundTripper(&transport)}
+			client.Get("http://example.com/routed")
+			client.Post("http://example.com/routed", "application/json", nil)
+			client.Get("http://foo.bar/routed")
+			client.Post("http://foo.bar/routed", "application/json", nil)
+			Expect(called).Should(Equal([]string{"get", "post", "get", "post"}))
+		})
+
+		It("should send http traffic to test server with default transport", func() {
+			transport := http.Transport{}
+			client := http.Client{Transport: s.RoundTripper(&transport)}
+			client.Get("https://example.com/routed")
+			client.Post("https://example.com/routed", "application/json", nil)
+			client.Get("https://foo.bar/routed")
+			client.Post("https://foo.bar/routed", "application/json", nil)
+			Expect(called).Should(Equal([]string{"get", "post", "get", "post"}))
+		})
+
+		It("should not change the path of the request", func() {
+			client := http.Client{Transport: s.RoundTripper(nil)}
+			client.Get("https://example.com/routed")
+			Expect(called).Should(Equal([]string{"get"}))
+			Expect(s.ReceivedRequests()).Should(HaveLen(1))
+			Expect(s.ReceivedRequests()[0].URL.Path).Should(Equal("/routed"))
+		})
+	})
 })