Move dummy service implementations into their own package.

go/src/infra/gae/libs/gae/dummy/dummy.go

Index: go/src/infra/gae/libs/gae/dummy/dummy.go
diff --git a/go/src/infra/gae/libs/gae/dummy/dummy.go b/go/src/infra/gae/libs/gae/dummy/dummy.go
new file mode 100644
index 0000000000000000000000000000000000000000..203c52e5739d5f4a27eea626385657e835a55950
--- /dev/null
+++ b/go/src/infra/gae/libs/gae/dummy/dummy.go
@@ -0,0 +1,177 @@
+// 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 dummy
+
+import (
+	"fmt"
+	"golang.org/x/net/context"
+	"runtime"
+	"strings"
+	"time"
+
+	"infra/gae/libs/gae"
+)
+
+const niFmtStr = "dummy: method %s.%s is not implemented"
+
+func ni() error {

[estaab, 2015/07/13 18:26:35]

Add a comment saying what this does since the acronym isn't obvious and the
implementation uses (admittedly cool) reflection magic.

[iannucci, 2015/07/14 01:35:53]

Done.

+	iface := "UNKNOWN"
+	funcName := "UNKNOWN"
+
+	if ptr, _, _, ok := runtime.Caller(1); ok {
+		f := runtime.FuncForPC(ptr)
+		n := f.Name()
+		if n != "" {
+			parts := strings.Split(n, ".")
+			if len(parts) == 3 {
+				switch parts[1] {
+				case "rds":
+					iface = "RawDatastore"
+				case "mc":
+					iface = "Memcache"
+				case "tq":
+					iface = "TaskQueue"
+				case "gi":
+					iface = "GlobalInformation"
+				case "qy":
+					iface = "DSQuery"
+				}
+				funcName = parts[2]
+			}
+		}
+	}
+
+	return fmt.Errorf(niFmtStr, iface, funcName)
+}
+
+/////////////////////////////////// rds ////////////////////////////////////
+
+type rds struct{}
+
+func (rds) NewKey(string, string, int64, gae.DSKey) gae.DSKey              { panic(ni()) }
+func (rds) DecodeKey(string) (gae.DSKey, error)                            { panic(ni()) }
+func (rds) KeyFromTokens(a, n string, t []gae.DSKeyTok) (gae.DSKey, error) { panic(ni()) }
+func (rds) Put(gae.DSKey, interface{}) (gae.DSKey, error)                  { panic(ni()) }
+func (rds) Get(gae.DSKey, interface{}) error                               { panic(ni()) }
+func (rds) Delete(gae.DSKey) error                                         { panic(ni()) }
+func (rds) PutMulti([]gae.DSKey, interface{}) ([]gae.DSKey, error)         { panic(ni()) }
+func (rds) GetMulti([]gae.DSKey, interface{}) error                        { panic(ni()) }
+func (rds) DeleteMulti([]gae.DSKey) error                                  { panic(ni()) }
+func (rds) NewQuery(string) gae.DSQuery                                    { panic(ni()) }
+func (rds) Run(gae.DSQuery) gae.DSIterator                                 { panic(ni()) }
+func (rds) GetAll(gae.DSQuery, interface{}) ([]gae.DSKey, error)           { panic(ni()) }
+func (rds) Count(gae.DSQuery) (int, error)                                 { panic(ni()) }
+func (rds) RunInTransaction(func(context.Context) error, *gae.DSTransactionOptions) error {
+	panic(ni())
+}
+
+var dummyRDSInst = rds{}
+
+// RDS returns a dummy RawDatastore implementation suitable for embedding.

[estaab, 2015/07/13 18:26:35]

Do we typically include file-level comments describing at a high level what's
included? Having this comment near the top explaining that this file just
contains panicking implementations for the 4 gae interfaces could save readers a
couple minutes.

[iannucci, 2015/07/14 01:35:52]

Added a doc.go :)

+// Every method panics with a message containing the name of the method which
+// was unimplemented.
+func RDS() gae.RawDatastore { return dummyRDSInst }

[estaab, 2015/07/13 18:26:35]

Could we spell these public functions out, at least? It's a little hard to read
as-is.

[iannucci, 2015/07/14 01:35:52]

This is mimicing the format of the gae package itself (e.g. gae.GetRDS), as well
as the 2/3 letter prefixes there. It gets very (very) verbose when spelling them
all out. Note that this function will only ever show up elsewhere as
`dummy.RDS()`, which is pretty clear (imho :)). If you feel strongly about it, I
can expand them (but I would be loathe to expand the ones in the gae package
since they get used everywhere in client code).

+
+/////////////////////////////////// mc ////////////////////////////////////
+
+type mc struct{}
+
+func (mc) Add(gae.MCItem) error                             { panic(ni()) }
+func (mc) NewItem(key string) gae.MCItem                    { panic(ni()) }
+func (mc) Set(gae.MCItem) error                             { panic(ni()) }
+func (mc) Get(string) (gae.MCItem, error)                   { panic(ni()) }
+func (mc) Delete(string) error                              { panic(ni()) }
+func (mc) CompareAndSwap(gae.MCItem) error                  { panic(ni()) }
+func (mc) AddMulti([]gae.MCItem) error                      { panic(ni()) }
+func (mc) SetMulti([]gae.MCItem) error                      { panic(ni()) }
+func (mc) GetMulti([]string) (map[string]gae.MCItem, error) { panic(ni()) }
+func (mc) DeleteMulti([]string) error                       { panic(ni()) }
+func (mc) CompareAndSwapMulti([]gae.MCItem) error           { panic(ni()) }
+func (mc) Increment(string, int64, uint64) (uint64, error)  { panic(ni()) }
+func (mc) IncrementExisting(string, int64) (uint64, error)  { panic(ni()) }
+func (mc) Flush() error                                     { panic(ni()) }
+func (mc) Stats() (*gae.MCStatistics, error)                { panic(ni()) }
+func (mc) InflateCodec(gae.MCCodecDef) gae.MCCodec          { panic(ni()) }
+
+var dummyMCInst = mc{}
+
+// MC returns a dummy Memcache implementation suitable for embedding.
+// Every method panics with a message containing the name of the method which
+// was unimplemented.
+func MC() gae.Memcache { return dummyMCInst }
+
+/////////////////////////////////// tq ////////////////////////////////////
+
+type tq struct{}
+
+func (tq) Add(*gae.TQTask, string) (*gae.TQTask, error)               { panic(ni()) }
+func (tq) Delete(*gae.TQTask, string) error                           { panic(ni()) }
+func (tq) AddMulti([]*gae.TQTask, string) ([]*gae.TQTask, error)      { panic(ni()) }
+func (tq) DeleteMulti([]*gae.TQTask, string) error                    { panic(ni()) }
+func (tq) Lease(int, string, int) ([]*gae.TQTask, error)              { panic(ni()) }
+func (tq) LeaseByTag(int, string, int, string) ([]*gae.TQTask, error) { panic(ni()) }
+func (tq) ModifyLease(*gae.TQTask, string, int) error                 { panic(ni()) }
+func (tq) Purge(string) error                                         { panic(ni()) }
+func (tq) QueueStats([]string) ([]gae.TQStatistics, error)            { panic(ni()) }
+
+var dummyTQInst = tq{}
+
+// TQ returns a dummy TaskQueue implementation suitable for embedding.
+// Every method panics with a message containing the name of the method which
+// was unimplemented.
+func TQ() gae.TaskQueue { return dummyTQInst }
+
+/////////////////////////////////// qy ////////////////////////////////////
+
+type qy struct{}
+
+func (qy) Ancestor(ancestor gae.DSKey) gae.DSQuery                { panic(ni()) }
+func (qy) Distinct() gae.DSQuery                                  { panic(ni()) }
+func (qy) End(c gae.DSCursor) gae.DSQuery                         { panic(ni()) }
+func (qy) EventualConsistency() gae.DSQuery                       { panic(ni()) }
+func (qy) Filter(filterStr string, value interface{}) gae.DSQuery { panic(ni()) }
+func (qy) KeysOnly() gae.DSQuery                                  { panic(ni()) }
+func (qy) Limit(limit int) gae.DSQuery                            { panic(ni()) }
+func (qy) Offset(offset int) gae.DSQuery                          { panic(ni()) }
+func (qy) Order(fieldName string) gae.DSQuery                     { panic(ni()) }
+func (qy) Project(fieldNames ...string) gae.DSQuery               { panic(ni()) }
+func (qy) Start(c gae.DSCursor) gae.DSQuery                       { panic(ni()) }
+
+var dummyQYInst = qy{}
+
+// QY returns a dummy gae.DSQuery implementation suitable for embedding.
+// Every method panics with a message containing the name of the method which
+// was unimplemented.
+func QY() gae.DSQuery { return dummyQYInst }
+
+/////////////////////////////////// gi ////////////////////////////////////
+
+type gi struct{}
+
+func (gi) AccessToken(scopes ...string) (token string, expiry time.Time, err error) { panic(ni()) }
+func (gi) AppID() string                                                            { panic(ni()) }
+func (gi) ModuleHostname(module, version, instance string) (string, error)          { panic(ni()) }
+func (gi) ModuleName() string                                                       { panic(ni()) }
+func (gi) DefaultVersionHostname() string                                           { panic(ni()) }
+func (gi) PublicCertificates() ([]gae.GICertificate, error)                         { panic(ni()) }
+func (gi) RequestID() string                                                        { panic(ni()) }
+func (gi) ServiceAccount() (string, error)                                          { panic(ni()) }
+func (gi) SignBytes(bytes []byte) (keyName string, signature []byte, err error)     { panic(ni()) }
+func (gi) VersionID() string                                                        { panic(ni()) }
+func (gi) Namespace(namespace string) (context.Context, error)                      { panic(ni()) }
+func (gi) Datacenter() string                                                       { panic(ni()) }
+func (gi) InstanceID() string                                                       { panic(ni()) }
+func (gi) IsDevAppServer() bool                                                     { panic(ni()) }
+func (gi) ServerSoftware() string                                                   { panic(ni()) }
+func (gi) IsCapabilityDisabled(err error) bool                                      { panic(ni()) }
+func (gi) IsOverQuota(err error) bool                                               { panic(ni()) }
+func (gi) IsTimeoutError(err error) bool                                            { panic(ni()) }
+
+var dummyGIInst = gi{}
+
+// GI returns a dummy GlobalInfo implementation suitable for embedding.
+// Every method panics with a message containing the name of the method which
+// was unimplemented.
+func GI() gae.GlobalInfo { return dummyGIInst }