Add Info Testable interface, implement for memory.

impl/memory/info.go

Index: impl/memory/info.go
diff --git a/impl/memory/info.go b/impl/memory/info.go
index 6d28d5ab45478255432528ab560d1442b1c8b766..432f70195ee82efab6f464cde55b466392c049af 100644
--- a/impl/memory/info.go
+++ b/impl/memory/info.go
@@ -20,23 +20,46 @@ var giContextKey giContextKeyType
 // validNamespace matches valid namespace names.
 var validNamespace = regexp.MustCompile(`^[0-9A-Za-z._-]{0,100}$`)
 
+var defaultGlobalInfoData = globalInfoData{
+	// versionID returns X.Y where Y is autogenerated by appengine, and X is
+	// whatever's in app.yaml.
+	versionID: "testVersionID.1",
+	requestID: "test-request-id",
+}
+
+type globalInfoData struct {
+	appid     string
+	namespace string
+	versionID string
+	requestID string
+}
+
 func curGID(c context.Context) *globalInfoData {
-	return c.Value(giContextKey).(*globalInfoData)
+	if gid, ok := c.Value(giContextKey).(*globalInfoData); ok {
+		return gid
+	}
+	return &defaultGlobalInfoData
+}
+
+func useGID(c context.Context, f func(mod *globalInfoData)) context.Context {
+	cur := curGID(c)
+	if cur == nil {
+		cur = &defaultGlobalInfoData
+	}
+
+	clone := *cur
+	f(&clone)
+	return context.WithValue(c, giContextKey, &clone)
 }
 
 // useGI adds a gae.GlobalInfo context, accessible
 // by gae.GetGI(c)
-func useGI(c context.Context, appID string) context.Context {
+func useGI(c context.Context) context.Context {
 	return info.SetFactory(c, func(ic context.Context) info.Interface {
 		return &giImpl{dummy.Info(), curGID(ic), ic}
 	})
 }
 
-type globalInfoData struct {
-	appid     string
-	namespace string
-}
-
 type giImpl struct {
 	info.Interface
 	*globalInfoData
@@ -53,7 +76,10 @@ func (gi *giImpl) Namespace(ns string) (ret context.Context, err error) {
 	if !validNamespace.MatchString(ns) {
 		return nil, fmt.Errorf("appengine: namespace %q does not match /%s/", ns, validNamespace)
 	}
-	return context.WithValue(gi.c, giContextKey, &globalInfoData{gi.appid, ns}), nil
+
+	return useGID(gi.c, func(mod *globalInfoData) {
+		mod.namespace = ns
+	}), nil
 }
 
 func (gi *giImpl) MustNamespace(ns string) context.Context {
@@ -77,7 +103,25 @@ func (gi *giImpl) IsDevAppServer() bool {
 }
 
 func (gi *giImpl) VersionID() string {
-	// VersionID returns X.Y where Y is autogenerated by appengine, and X is
-	// whatever's in app.yaml.
-	return "testVersionID.1"
+	return curGID(gi.c).versionID
+}
+
+func (gi *giImpl) RequestID() string {
+	return curGID(gi.c).requestID
+}
+
+func (gi *giImpl) Testable() info.Testable {
+	return gi
+}
+
+func (gi *giImpl) SetVersionID(v string) context.Context {
+	return useGID(gi.c, func(mod *globalInfoData) {
+		mod.versionID = v
+	})
+}
+
+func (gi *giImpl) SetRequestID(v string) context.Context {
+	return useGID(gi.c, func(mod *globalInfoData) {
+		mod.requestID = v
+	})
 }