auth: Make luci-go services trust signatures produced by the token server.

server/auth/internal/testing.go

Index: server/auth/internal/testing.go
diff --git a/server/auth/internal/testing.go b/server/auth/internal/testing.go
new file mode 100644
index 0000000000000000000000000000000000000000..9e9b7aef12f63d59c4a751e23243c9d5f6c59f3f
--- /dev/null
+++ b/server/auth/internal/testing.go
@@ -0,0 +1,44 @@
+// Copyright 2015 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package internal
+
+import (
+	"bytes"
+	"io/ioutil"
+	"net/http"
+	"sync"
+
+	"golang.org/x/net/context"
+)
+
+var testTransportKey = "testTransport"
+
+// TestTransportCallback is used from unit tests.
+type TestTransportCallback func(r *http.Request, body string) (code int, response string)
+
+// WithTestTransport puts a testing transport in the context to use for fetches.
+func WithTestTransport(c context.Context, cb TestTransportCallback) context.Context {
+	return context.WithValue(c, &testTransportKey, &testTransport{cb: cb})
+}
+
+type testTransport struct {
+	lock sync.Mutex
+	cb   TestTransportCallback
+}
+
+func (t *testTransport) RoundTrip(r *http.Request) (*http.Response, error) {
+	t.lock.Lock()
+	defer t.lock.Unlock()
+	body, err := ioutil.ReadAll(r.Body)
+	r.Body.Close()
+	if err != nil {
+		return nil, err
+	}
+	code, resp := t.cb(r, string(body))
+	return &http.Response{
+		StatusCode: code,
+		Body:       ioutil.NopCloser(bytes.NewReader([]byte(resp))),
+	}, nil
+}