Better attempt at an appengine wrapper.

go/src/infra/gae/libs/wrapper/doc.go

Index: go/src/infra/gae/libs/wrapper/doc.go
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+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Package wrapper provides a fakable wrapped interface for the appengine SDK's
+// APIs. This means that it's possible to mock all of the supported appengine
+// APIs for testing (or potentially implement a different backend for them,
+// though you would still need to provide enough of the appengine SDK for a
+// few key types).
+//
+// wrapper currently provides interfaces for:
+//   * Datastore
+//   * Memcache
+//   * TaskQueue
+//   * GlobalInfo (e.g. Namespace, AppID, etc.)
+//
+// A package which implements the wrapper is expected to provide the following:
+//   * A package function `Enable(c context.Context, ...) context.Context`
+//     This function is expected to add any information to c which is necessary
+//     for the rest of its implementations to work. This may be something like
+//     an `appengine.Context` or some connection information for an external
+//     server. The `...` in the function signature may be any additional data
+//     needed.
+//   * Any of the package functions:
+//
+//       UseDS(context.Context) context.Context
+//       UseMC(context.Context) context.Context
+//		   UseTQ(context.Context) context.Context
+//       UseGI(context.Context) context.Context
+//
+//	   each of which would call wrapper.Set<service>Factory with the factory
+//	   function for that interface type.
+//	 * A `Use(context.Context) context.Context` function which calls all of the
+//	   `Use*` package functions implemented by the package.
+//   * Partially-implemented interfaces should embed one of the Dummy* structs
+//     which will panic with an appropriate error for unimplemented
+//     methods.
+//
+// see "infra/gae/libs/wrapper/gae" for an appengine-backed implementation.
+package wrapper