Move test util functions to dedicated file to clean up test files

Also use verbose mode on tests so you can see which test is running when things
print to stdout.

hooks/pre-commit

@@ -6,4 +6,4 @@ golint src/...
 go fmt ./src/...
 go tool vet --shadow ./src
 gocyclo -over 12 src/
-gb test -timeout 5s
+gb test -timeout 5s -test.v

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

@@ -2,7 +2,6 @@ package main
 
 import (
 	"bytes"
-	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -10,45 +9,7 @@ import (
 )
 
 var mux = http.NewServeMux()
-
-type MockTripper struct {
-	handlers map[string]func(req *http.Request) (*http.Response, error)
-}
-
-func (rt MockTripper) RoundTrip(req *http.Request) (*http.Response, error) {
-	key := req.Method + " " + req.URL.Path
-	h := rt.handlers[key]
-	if h == nil {
-		panic(
-			fmt.Sprintf("Test RoundTrip: Unhandled request: %s\nHandlers: %d",
-				key, len(rt.handlers)),
-		)
-	}
-	return h(req)
-}
-
-func (rt MockTripper) Handle(method, path string, handler func(req *http.Request) (*http.Response, error)) {
-	key := method + " " + path
-	if _, exists := rt.handlers[key]; exists {
-		panic("Test handler with key " + key + " already exists")
-	}
-	rt.handlers[key] = handler
-}
-
-var tripper = MockTripper{make(map[string]func(req *http.Request) (*http.Response, error))}
-
-type nopCloser struct {
-	*bytes.Buffer
-}
-
-func (nopCloser) Close() error { return nil }
-
-func newResponse(statusCode int, body string) *http.Response {
-	return &http.Response{
-		StatusCode: statusCode,
-		Body:       nopCloser{bytes.NewBufferString(body)},
-	}
-}
+var mxTripper = newMatrixTripper()
 
 func TestMain(m *testing.M) {
 	setup(envVars{
@@ -56,26 +17,18 @@ func TestMain(m *testing.M) {
 		DatabaseType: "sqlite3",
 		DatabaseURL:  ":memory:",
 	}, mux, &http.Client{
-		Transport: tripper,
+		Transport: mxTripper,
 	})
 	exitCode := m.Run()
 	os.Exit(exitCode)
 }
 
 func TestConfigureClient(t *testing.T) {
-	for k := range tripper.handlers {
-		delete(tripper.handlers, k)
-	}
+	mxTripper.ClearHandlers()
 	mockWriter := httptest.NewRecorder()
-	tripper.Handle("POST", "/_matrix/client/r0/user/@link:hyrule/filter",
-		func(req *http.Request) (*http.Response, error) {
-			return newResponse(200, `{
-				"filter_id":"abcdef"
-			}`), nil
-		},
-	)
 	syncChan := make(chan string)
-	tripper.Handle("GET", "/_matrix/client/r0/sync",
+	mxTripper.HandlePOSTFilter("@link:hyrule")
+	mxTripper.Handle("GET", "/_matrix/client/r0/sync",
 		func(req *http.Request) (*http.Response, error) {
 			syncChan <- "sync"
 			return newResponse(200, `{

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

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+)
+
+// newResponse creates a new HTTP response with the given data.
+func newResponse(statusCode int, body string) *http.Response {
+	return &http.Response{
+		StatusCode: statusCode,
+		Body:       ioutil.NopCloser(bytes.NewBufferString(body)),
+	}
+}
+
+// matrixTripper mocks out RoundTrip and calls a registered handler instead.
+type matrixTripper struct {
+	handlers map[string]func(req *http.Request) (*http.Response, error)
+}
+
+func newMatrixTripper() *matrixTripper {
+	return &matrixTripper{
+		handlers: make(map[string]func(req *http.Request) (*http.Response, error)),
+	}
+}
+
+func (rt *matrixTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	key := req.Method + " " + req.URL.Path
+	h := rt.handlers[key]
+	if h == nil {
+		panic(fmt.Sprintf(
+			"RoundTrip: Unhandled request: %s\nHandlers: %d",
+			key, len(rt.handlers),
+		))
+	}
+	return h(req)
+}
+
+func (rt *matrixTripper) Handle(method, path string, handler func(req *http.Request) (*http.Response, error)) {
+	key := method + " " + path
+	if _, exists := rt.handlers[key]; exists {
+		panic(fmt.Sprintf("Test handler with key %s already exists", key))
+	}
+	rt.handlers[key] = handler
+}
+
+func (rt *matrixTripper) HandlePOSTFilter(userID string) {
+	rt.Handle("POST", "/_matrix/client/r0/user/"+userID+"/filter",
+		func(req *http.Request) (*http.Response, error) {
+			return newResponse(200, `{
+				"filter_id":"abcdef"
+			}`), nil
+		},
+	)
+}
+
+func (rt *matrixTripper) ClearHandlers() {
+	for k := range rt.handlers {
+		delete(rt.handlers, k)
+	}
+}