Add a dedicated testutils package

In the spirit of "if you have to do something 3 times then factor it
out", make a testutils package to put all the `RoundTrip` boilerplate.

I don't overly like having test packages, especially mixed in with
code, but I don't see a nicer way of doing this without ending up
with a sprawling mess of copypasta'd test boilerplate which will
be an absolute nightmare to maintain.

I think this is the lesser of two evils.

src/github.com/matrix-org/go-neb/services/guggy/guggy_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"github.com/matrix-org/go-neb/database"
 	"github.com/matrix-org/go-neb/matrix"
+	"github.com/matrix-org/go-neb/testutils"
 	"github.com/matrix-org/go-neb/types"
 	"io/ioutil"
 	"net/http"
@@ -14,14 +15,6 @@ import (
 	"testing"
 )
 
-type MockTransport struct {
-	roundTrip func(*http.Request) (*http.Response, error)
-}
-
-func (t MockTransport) RoundTrip(req *http.Request) (*http.Response, error) {
-	return t.roundTrip(req)
-}
-
 // TODO: It would be nice to tabularise this test so we can try failing different combinations of responses to make
 //       sure all cases are handled, rather than just the general case as is here.
 func TestCommand(t *testing.T) {
@@ -30,8 +23,8 @@ func TestCommand(t *testing.T) {
 	guggyImageURL := "https://guggy.com/gifs/23ryf872fg"
 
 	// Mock the response from Guggy
-	guggyTrans := struct{ MockTransport }{}
-	guggyTrans.roundTrip = func(req *http.Request) (*http.Response, error) {
+	guggyTrans := struct{ testutils.MockTransport }{}
+	guggyTrans.RT = func(req *http.Request) (*http.Response, error) {
 		guggyURL := "https://text2gif.guggy.com/guggify"
 		if req.URL.String() != guggyURL {
 			t.Fatalf("Bad URL: got %s want %s", req.URL.String(), guggyURL)
@@ -79,8 +72,8 @@ func TestCommand(t *testing.T) {
 	guggy := srv.(*Service)
 
 	// Mock the response from Matrix
-	matrixTrans := struct{ MockTransport }{}
-	matrixTrans.roundTrip = func(req *http.Request) (*http.Response, error) {
+	matrixTrans := struct{ testutils.MockTransport }{}
+	matrixTrans.RT = func(req *http.Request) (*http.Response, error) {
 		if req.URL.String() == guggyImageURL { // getting the guggy image
 			return &http.Response{
 				StatusCode: 200,

src/github.com/matrix-org/go-neb/services/rssbot/rssbot_test.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/matrix-org/go-neb/database"
 	"github.com/matrix-org/go-neb/matrix"
+	"github.com/matrix-org/go-neb/testutils"
 	"github.com/matrix-org/go-neb/types"
 )
 
@@ -36,20 +37,12 @@ const rssFeedXML = `
 </channel>
 </rss>`
 
-type MockTransport struct {
-	roundTrip func(*http.Request) (*http.Response, error)
-}
-
-func (t MockTransport) RoundTrip(req *http.Request) (*http.Response, error) {
-	return t.roundTrip(req)
-}
-
 func TestHTMLEntities(t *testing.T) {
 	database.SetServiceDB(&database.NopStorage{})
 	feedURL := "https://thehappymaskshop.hyrule"
 	// Replace the cachingClient with a mock so we can intercept RSS requests
-	rssTrans := struct{ MockTransport }{}
-	rssTrans.roundTrip = func(req *http.Request) (*http.Response, error) {
+	rssTrans := struct{ testutils.MockTransport }{}
+	rssTrans.RT = func(req *http.Request) (*http.Response, error) {
 		if req.URL.String() != feedURL {
 			return nil, errors.New("Unknown test URL")
 		}
@@ -79,8 +72,8 @@ func TestHTMLEntities(t *testing.T) {
 	// Create the Matrix client which will send the notification
 	wg := sync.WaitGroup{}
 	wg.Add(1)
-	matrixTrans := struct{ MockTransport }{}
-	matrixTrans.roundTrip = func(req *http.Request) (*http.Response, error) {
+	matrixTrans := struct{ testutils.MockTransport }{}
+	matrixTrans.RT = func(req *http.Request) (*http.Response, error) {
 		if strings.HasPrefix(req.URL.Path, "/_matrix/client/r0/rooms/!linksroom:hyrule/send/m.room.message") {
 			// Check content body to make sure it is decoded
 			var msg matrix.HTMLMessage

src/github.com/matrix-org/go-neb/services/travisci/travisci_test.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/matrix-org/go-neb/database"
 	"github.com/matrix-org/go-neb/matrix"
+	"github.com/matrix-org/go-neb/testutils"
 	"github.com/matrix-org/go-neb/types"
 )
 
@@ -91,14 +92,6 @@ var travisTests = []struct {
 	},
 }
 
-type MockTransport struct {
-	roundTrip func(*http.Request) (*http.Response, error)
-}
-
-func (t MockTransport) RoundTrip(req *http.Request) (*http.Response, error) {
-	return t.roundTrip(req)
-}
-
 func TestTravisCI(t *testing.T) {
 	database.SetServiceDB(&database.NopStorage{})
 
@@ -106,8 +99,8 @@ func TestTravisCI(t *testing.T) {
 	urlToKey := make(map[string]string)
 	urlToKey["https://api.travis-ci.org/config"] = travisOrgPEMPublicKey
 	urlToKey["https://api.travis-ci.com/config"] = travisComPEMPublicKey
-	travisTransport := struct{ MockTransport }{}
-	travisTransport.roundTrip = func(req *http.Request) (*http.Response, error) {
+	travisTransport := struct{ testutils.MockTransport }{}
+	travisTransport.RT = func(req *http.Request) (*http.Response, error) {
 		if key := urlToKey[req.URL.String()]; key != "" {
 			escKey, _ := json.Marshal(key)
 			return &http.Response{
@@ -124,8 +117,8 @@ func TestTravisCI(t *testing.T) {
 
 	// Intercept message sending to Matrix and mock responses
 	msgs := []matrix.TextMessage{}
-	matrixTrans := struct{ MockTransport }{}
-	matrixTrans.roundTrip = func(req *http.Request) (*http.Response, error) {
+	matrixTrans := struct{ testutils.MockTransport }{}
+	matrixTrans.RT = func(req *http.Request) (*http.Response, error) {
 		if !strings.Contains(req.URL.String(), "/send/m.room.message") {
 			return nil, fmt.Errorf("Unhandled URL: %s", req.URL.String())
 		}

src/github.com/matrix-org/go-neb/testutils/testutils.go

@@ -0,0 +1,15 @@
+package testutils
+
+import (
+	"net/http"
+)
+
+// MockTransport implements RoundTripper
+type MockTransport struct {
+	RT func(*http.Request) (*http.Response, error)
+}
+
+// RoundTrip is a RoundTripper
+func (t MockTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	return t.RT(req)
+}