datastore: variadic Get, Put, Exists, Delete.

service/datastore/datastore_test.go

 // 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.
 
 // adapted from github.com/golang/appengine/datastore
 
 package datastore
 
 import (
         "bytes"
@@ skipping 52 matching lines @@
                 if err := cb(k, pm, cursCB); err != nil {
                         if err == Stop {
                                 err = nil
                         }
                         return err
                 }
         }
         return nil
 }
 
+var (
+        errFail    = errors.New("Individual element fail")
+        errFailAll = errors.New("Operation fail")
+)
+
 func (f *fakeDatastore) PutMulti(keys []*Key, vals []PropertyMap, cb PutMultiCB) error {
         if keys[0].Kind() == "FailAll" {
-                return errors.New("PutMulti fail all")
+                return errFailAll
         }
         _, assertExtra := vals[0].GetMeta("assertExtra")
         for i, k := range keys {
                 err := error(nil)
                 if k.Kind() == "Fail" {
-                        err = errors.New("PutMulti fail")
+                        err = errFail
                 } else {
                         So(vals[i]["Value"], ShouldResemble, []Property{MkProperty(i)})
                         if assertExtra {
                                 So(vals[i]["Extra"], ShouldResemble, []Property{MkProperty("whoa")})
                         }
                         if k.Incomplete() {
                                 k = NewKey(k.AppID(), k.Namespace(), k.Kind(), "", int64(i+1), k.Parent())
                         }
                 }
                 cb(k, err)
         }
         return nil
 }
 
+const noSuchEntityID = 0xdead
+
 func (f *fakeDatastore) GetMulti(keys []*Key, _meta MultiMetaGetter, cb GetMultiCB) error {
         if keys[0].Kind() == "FailAll" {
-                return errors.New("GetMulti fail all")
+                return errFailAll
         }
         for i, k := range keys {
                 if k.Kind() == "Fail" {
-                        cb(nil, errors.New("GetMulti fail"))
-                } else if k.Kind() == "DNE" {
+                        cb(nil, errFail)
+                } else if k.Kind() == "DNE" || k.IntID() == noSuchEntityID {
                         cb(nil, ErrNoSuchEntity)
                 } else {
                         cb(PropertyMap{"Value": {MkProperty(i + 1)}}, nil)
                 }
         }
         return nil
 }
 
 func (f *fakeDatastore) DeleteMulti(keys []*Key, cb DeleteMultiCB) error {
         if keys[0].Kind() == "FailAll" {
-                return errors.New("DeleteMulti fail all")
+                return errFailAll
         }
         for _, k := range keys {
                 if k.Kind() == "Fail" {
-                        cb(errors.New("DeleteMulti fail"))
+                        cb(errFail)
+                } else if k.Kind() == "DNE" || k.IntID() == noSuchEntityID {
+                        cb(ErrNoSuchEntity)
                 } else {
                         cb(nil)
                 }
         }
         return nil
 }
 
 type badStruct struct {
         ID    int64     `gae:"$id"`
         Compy complex64 // bad type
@@ skipping 124 matching lines @@
 
 type MGSWithNoKind struct {
         S string
 }
 
 func (s *MGSWithNoKind) GetMeta(key string) (interface{}, bool) {
         return nil, false
 }
 
 func (s *MGSWithNoKind) GetAllMeta() PropertyMap {
-        return PropertyMap{}
+        return PropertyMap{"$kind": []Property{MkProperty("wang")}}
 }
 
 func (s *MGSWithNoKind) SetMeta(key string, val interface{}) bool {
         return false
 }
 
 var _ MetaGetterSetter = (*MGSWithNoKind)(nil)
 
 func TestKeyForObj(t *testing.T) {
         t.Parallel()
@@ skipping 46 matching lines @@
                                 So(ds.KeyForObj(pm).String(), ShouldEqual, `s~aid:ns:/Hello,"world"/Sup,100`)
                         })
 
                         Convey("a pls with $id, $parent", func() {
                                 pls := GetPLS(&CommonStruct{ID: 1})
                                 So(ds.KeyForObj(pls).String(), ShouldEqual, `s~aid:ns:/CommonStruct,1`)
 
                                 So(pls.SetMeta("parent", k), ShouldBeTrue)
                                 So(ds.KeyForObj(pls).String(), ShouldEqual, `s~aid:ns:/Hello,"world"/CommonStruct,1`)
                         })
-
-                        Convey("can see if things exist", func() {
-                                e, err := ds.Exists(k)
-                                So(err, ShouldBeNil)
-                                So(e, ShouldBeTrue)
-
-                                bl, err := ds.ExistsMulti([]*Key{k, ds.MakeKey("hello", "other")})
-                                So(err, ShouldBeNil)
-                                So(bl, ShouldResemble, BoolList{true, true})
-                                So(bl.All(), ShouldBeTrue)
-                                So(bl.Any(), ShouldBeTrue)
-
-                                bl, err = ds.ExistsMulti([]*Key{k, ds.MakeKey("DNE", "other")})
-                                So(err, ShouldBeNil)
-                                So(bl, ShouldResemble, BoolList{true, false})
-                                So(bl.All(), ShouldBeFalse)
-                                So(bl.Any(), ShouldBeTrue)
-
-                                e, err = ds.Exists(ds.MakeKey("DNE", "nope"))
-                                So(err, ShouldBeNil)
-                                So(e, ShouldBeFalse)
-
-                                bl, err = ds.ExistsMulti([]*Key{ds.MakeKey("DNE", "nope"), ds.MakeKey("DNE", "other")})
-                                So(err, ShouldBeNil)
-                                So(bl, ShouldResemble, BoolList{false, false})
-                                So(bl.All(), ShouldBeFalse)
-                                So(bl.Any(), ShouldBeFalse)
-
-                                _, err = ds.Exists(ds.MakeKey("Fail", "boom"))
-                                So(err, ShouldErrLike, "GetMulti fail")
-                        })
-
                 })
 
                 Convey("bad", func() {
                         Convey("a propmap without $kind", func() {
                                 pm := PropertyMap{}
                                 So(pm.SetMeta("id", 100), ShouldBeTrue)
                                 So(func() { ds.KeyForObj(pm) }, ShouldPanic)
                         })
 
                         Convey("a bad object", func() {
@@ skipping 40 matching lines @@
                         var broken permaBad
 
                         So(func() { PopulateKey(&broken, k) }, ShouldPanic)
                 })
         })
 }
 
 func TestPut(t *testing.T) {
         t.Parallel()
 
-        Convey("Test Put/PutMulti", t, func() {
+        Convey("A testing environment", t, func() {
                 c := info.Set(context.Background(), fakeInfo{})
                 c = SetRawFactory(c, fakeDatastoreFactory)
                 ds := Get(c)
 
-                Convey("bad", func() {
-                        Convey("static can't serialize", func() {
-                                bss := []badStruct{{}, {}}
-                                So(func() { ds.PutMulti(bss) }, ShouldPanicLike,
-                                        `field "Compy" has invalid type`)
-                        })
-
-                        Convey("static ptr can't serialize", func() {
-                                bss := []*badStruct{{}, {}}
-                                So(func() { ds.PutMulti(bss) }, ShouldPanicLike,
-                                        `field "Compy" has invalid type: complex64`)
-                        })
-
-                        Convey("static bad type (non-slice)", func() {
-                                So(func() { ds.PutMulti(100) }, ShouldPanicLike,
-                                        "invalid argument type: expected slice, got int")
-                        })
-
-                        Convey("static bad type (slice of bad type)", func() {
-                                So(func() { ds.PutMulti([]int{}) }, ShouldPanicLike,
-                                        "invalid argument type: []int")
-                        })
-
-                        Convey("dynamic can't serialize", func() {
-                                fplss := []FakePLS{{failSave: true}, {}}
-                                So(ds.PutMulti(fplss), ShouldErrLike, "FakePLS.Save")
-                        })
-
-                        Convey("can't get keys", func() {
-                                fplss := []FakePLS{{failGetMeta: true}, {}}
-                                So(ds.PutMulti(fplss), ShouldErrLike, "unable to extract $kind")
-                        })
-
-                        Convey("get single error for RPC failure", func() {
-                                fplss := []FakePLS{{Kind: "FailAll"}, {}}
-                                So(ds.PutMulti(fplss), ShouldErrLike, "PutMulti fail all")
-                        })
-
-                        Convey("get multi error for individual failures", func() {
-                                fplss := []FakePLS{{}, {Kind: "Fail"}}
-                                So(ds.PutMulti(fplss), ShouldResemble, errors.MultiError{nil, errors.New("PutMulti fail")})
-                        })
-
-                        Convey("put with non-modifyable type is an error", func() {
+                Convey("Testing Put", func() {
+                        Convey("bad", func() {
+                                Convey("static can't serialize", func() {
+                                        bss := []badStruct{{}, {}}
+                                        So(func() { ds.Put(bss) }, ShouldPanicLike,
+                                                `field "Compy" has invalid type`)
+                                })
+
+                                Convey("static ptr can't serialize", func() {
+                                        bss := []*badStruct{{}, {}}
+                                        So(func() { ds.Put(bss) }, ShouldPanicLike,
+                                                `field "Compy" has invalid type: complex64`)
+                                })
+
+                                Convey("static bad type", func() {
+                                        So(func() { ds.Put(100) }, ShouldPanicLike,
+                                                "invalid input type (int): not a PLS or pointer-to-struct")
+                                })
+
+                                Convey("static bad type (slice of bad type)", func() {
+                                        So(func() { ds.Put([]int{}) }, ShouldPanicLike,
+                                                "invalid input type ([]int): not a PLS or pointer-to-struct")
+                                })
+
+                                Convey("dynamic can't serialize", func() {
+                                        fplss := []FakePLS{{failSave: true}, {}}
+                                        So(ds.Put(fplss), ShouldErrLike, "FakePLS.Save")
+                                })
+
+                                Convey("can't get keys", func() {
+                                        fplss := []FakePLS{{failGetMeta: true}, {}}
+                                        So(ds.Put(fplss), ShouldErrLike, "unable to extract $kind")
+                                })
+
+                                Convey("get single error for RPC failure", func() {
+                                        fplss := []FakePLS{{Kind: "FailAll"}, {}}
+                                        So(ds.Put(fplss), ShouldEqual, errFailAll)
+                                })
+
+                                Convey("get multi error for individual failures", func() {
+                                        fplss := []FakePLS{{}, {Kind: "Fail"}}
+                                        So(ds.Put(fplss), ShouldResemble, errors.MultiError{nil, errFail})
+                                })
+
+                                Convey("put with non-modifyable type is an error", func() {
+                                        cs := CommonStruct{}
+                                        So(func() { ds.Put(cs) }, ShouldPanicLike,
+                                                "invalid input type (datastore.CommonStruct): not a pointer")
+                                })
+
+                                Convey("get with *Key is an error", func() {
+                                        So(func() { ds.Get(&Key{}) }, ShouldPanicLike,
+                                                "invalid input type (*datastore.Key): not user datatype")
+                                })
+
+                                Convey("struct with no $kind is an error", func() {
+                                        s := MGSWithNoKind{}
+                                        So(ds.Put(&s), ShouldErrLike, "unable to extract $kind")
+                                })
+
+                                Convey("struct with invalid but non-nil key is an error", func() {
+                                        type BadParent struct {
+                                                ID     int64 `gae:"$id"`
+                                                Parent *Key  `gae:"$parent"`
+                                        }
+                                        // having an Incomplete parent makes an invalid key
+                                        bp := &BadParent{ID: 1, Parent: ds.MakeKey("Something", 0)}
+                                        So(ds.Put(bp), ShouldErrLike, ErrInvalidKey)
+                                })
+
+                                Convey("vararg with errors", func() {
+                                        successSlice := []CommonStruct{{Value: 0}, {Value: 1}}
+                                        failSlice := []FakePLS{{Kind: "Fail"}, {Value: 3}}
+                                        emptySlice := []CommonStruct(nil)
+                                        cs0 := CommonStruct{Value: 4}
+                                        cs1 := FakePLS{Kind: "Fail", Value: 5}
+                                        fpls := FakePLS{StringID: "ohai", Value: 6}
+
+                                        err := ds.Put(successSlice, failSlice, emptySlice, &cs0, &cs1, &fpls)
+                                        So(err, ShouldResemble, errors.MultiError{
+                                                nil, errors.MultiError{errFail, nil}, nil, nil, errFail, nil})
+                                        So(successSlice[0].ID, ShouldEqual, 1)
+                                        So(successSlice[1].ID, ShouldEqual, 2)
+                                        So(cs0.ID, ShouldEqual, 5)
+                                })
+                        })
+
+                        Convey("ok", func() {
+                                Convey("[]S", func() {
+                                        css := make([]CommonStruct, 7)
+                                        for i := range css {
+                                                if i == 4 {
+                                                        css[i].ID = 200
+                                                }
+                                                css[i].Value = int64(i)
+                                        }
+                                        So(ds.Put(css), ShouldBeNil)
+                                        for i, cs := range css {
+                                                expect := int64(i + 1)
+                                                if i == 4 {
+                                                        expect = 200
+                                                }
+                                                So(cs.ID, ShouldEqual, expect)
+                                        }
+                                })
+
+                                Convey("[]*S", func() {
+                                        css := make([]*CommonStruct, 7)
+                                        for i := range css {
+                                                css[i] = &CommonStruct{Value: int64(i)}
+                                                if i == 4 {
+                                                        css[i].ID = 200
+                                                }
+                                        }
+                                        So(ds.Put(css), ShouldBeNil)
+                                        for i, cs := range css {
+                                                expect := int64(i + 1)
+                                                if i == 4 {
+                                                        expect = 200
+                                                }
+                                                So(cs.ID, ShouldEqual, expect)
+                                        }
+
+                                        s := &CommonStruct{}
+                                        So(ds.Put(s), ShouldBeNil)
+                                        So(s.ID, ShouldEqual, 1)
+                                })
+
+                                Convey("[]P", func() {
+                                        fplss := make([]FakePLS, 7)
+                                        for i := range fplss {
+                                                fplss[i].Value = int64(i)
+                                                if i == 4 {
+                                                        fplss[i].IntID = int64(200)
+                                                }
+                                        }
+                                        So(ds.Put(fplss), ShouldBeNil)
+                                        for i, fpls := range fplss {
+                                                expect := int64(i + 1)
+                                                if i == 4 {
+                                                        expect = 200
+                                                }
+                                                So(fpls.IntID, ShouldEqual, expect)
+                                        }
+
+                                        pm := PropertyMap{"Value": {MkProperty(0)}, "$kind": {MkPropertyNI("Pmap")}}
+                                        So(ds.Put(pm), ShouldBeNil)
+                                        So(ds.KeyForObj(pm).IntID(), ShouldEqual, 1)
+                                })
+
+                                Convey("[]P (map)", func() {
+                                        pms := make([]PropertyMap, 7)
+                                        for i := range pms {
+                                                pms[i] = PropertyMap{
+                                                        "$kind": {MkProperty("Pmap")},
+                                                        "Value": {MkProperty(i)},
+                                                }
+                                                if i == 4 {
+                                                        So(pms[i].SetMeta("id", int64(200)), ShouldBeTrue)
+                                                }
+                                        }
+                                        So(ds.Put(pms), ShouldBeNil)
+                                        for i, pm := range pms {
+                                                expect := int64(i + 1)
+                                                if i == 4 {
+                                                        expect = 200
+                                                }
+                                                So(ds.KeyForObj(pm).String(), ShouldEqual, fmt.Sprintf("s~aid:ns:/Pmap,%d", expect))
+                                        }
+                                })
+
+                                Convey("[]*P", func() {
+                                        fplss := make([]*FakePLS, 7)
+                                        for i := range fplss {
+                                                fplss[i] = &FakePLS{Value: int64(i)}
+                                                if i == 4 {
+                                                        fplss[i].IntID = int64(200)
+                                                }
+                                        }
+                                        So(ds.Put(fplss), ShouldBeNil)
+                                        for i, fpls := range fplss {
+                                                expect := int64(i + 1)
+                                                if i == 4 {
+                                                        expect = 200
+                                                }
+                                                So(fpls.IntID, ShouldEqual, expect)
+                                        }
+                                })
+
+                                Convey("[]*P (map)", func() {
+                                        pms := make([]*PropertyMap, 7)
+                                        for i := range pms {
+                                                pms[i] = &PropertyMap{
+                                                        "$kind": {MkProperty("Pmap")},
+                                                        "Value": {MkProperty(i)},
+                                                }
+                                                if i == 4 {
+                                                        So(pms[i].SetMeta("id", int64(200)), ShouldBeTrue)
+                                                }
+                                        }
+                                        So(ds.Put(pms), ShouldBeNil)
+                                        for i, pm := range pms {
+                                                expect := int64(i + 1)
+                                                if i == 4 {
+                                                        expect = 200
+                                                }
+                                                So(ds.KeyForObj(*pm).String(), ShouldEqual, fmt.Sprintf("s~aid:ns:/Pmap,%d", expect))
+                                        }
+                                })
+
+                                Convey("[]I", func() {
+                                        ifs := []interface{}{
+                                                &CommonStruct{Value: 0},
+                                                &FakePLS{Value: 1},
+                                                PropertyMap{"Value": {MkProperty(2)}, "$kind": {MkPropertyNI("Pmap")}},
+                                                &PropertyMap{"Value": {MkProperty(3)}, "$kind": {MkPropertyNI("Pmap")}},
+                                        }
+                                        So(ds.Put(ifs), ShouldBeNil)
+                                        for i := range ifs {
+                                                switch i {
+                                                case 0:
+                                                        So(ifs[i].(*CommonStruct).ID, ShouldEqual, 1)
+                                                case 1:
+                                                        fpls := ifs[i].(*FakePLS)
+                                                        So(fpls.IntID, ShouldEqual, 2)
+                                                case 2:
+                                                        So(ds.KeyForObj(ifs[i].(PropertyMap)).String(), ShouldEqual, "s~aid:ns:/Pmap,3")
+                                                case 3:
+                                                        So(ds.KeyForObj(*ifs[i].(*PropertyMap)).String(), ShouldEqual, "s~aid:ns:/Pmap,4")
+                                                }
+                                        }
+                                })
+                        })
+                })
+
+                Convey("Testing PutMulti", func() {
+                        Convey("Fails for something other than a slice.", func() {
                                 cs := CommonStruct{}
-                                So(func() { ds.Put(cs) }, ShouldPanicLike,
-                                        "invalid Put input type (datastore.CommonStruct): not a pointer")
-                        })
-
-                        Convey("get with *Key is an error", func() {
-                                So(func() { ds.Get(&Key{}) }, ShouldPanicLike,
-                                        "invalid Get input type (*datastore.Key): not user datatype")
-                        })
-
-                        Convey("struct with no $kind is an error", func() {
-                                s := MGSWithNoKind{}
-                                So(ds.Put(&s), ShouldErrLike, "unable to extract $kind")
-                        })
-
-                        Convey("struct with invalid but non-nil key is an error", func() {
-                                type BadParent struct {
-                                        ID     int64 `gae:"$id"`
-                                        Parent *Key  `gae:"$parent"`
-                                }
-                                // having an Incomplete parent makes an invalid key
-                                bp := &BadParent{ID: 1, Parent: ds.MakeKey("Something", 0)}
-                                So(ds.Put(bp), ShouldErrLike, ErrInvalidKey)
-                        })
-                })
-
-                Convey("ok", func() {
-                        Convey("[]S", func() {
-                                css := make([]CommonStruct, 7)
-                                for i := range css {
-                                        if i == 4 {
-                                                css[i].ID = 200
-                                        }
-                                        css[i].Value = int64(i)
-                                }
-                                So(ds.PutMulti(css), ShouldBeNil)
-                                for i, cs := range css {
-                                        expect := int64(i + 1)
-                                        if i == 4 {
-                                                expect = 200
-                                        }
-                                        So(cs.ID, ShouldEqual, expect)
-                                }
-                        })
-
-                        Convey("[]*S", func() {
-                                css := make([]*CommonStruct, 7)
-                                for i := range css {
-                                        css[i] = &CommonStruct{Value: int64(i)}
-                                        if i == 4 {
-                                                css[i].ID = 200
-                                        }
-                                }
-                                So(ds.PutMulti(css), ShouldBeNil)
-                                for i, cs := range css {
-                                        expect := int64(i + 1)
-                                        if i == 4 {
-                                                expect = 200
-                                        }
-                                        So(cs.ID, ShouldEqual, expect)
-                                }
-
-                                s := &CommonStruct{}
-                                So(ds.Put(s), ShouldBeNil)
-                                So(s.ID, ShouldEqual, 1)
-                        })
-
-                        Convey("[]P", func() {
-                                fplss := make([]FakePLS, 7)
-                                for i := range fplss {
-                                        fplss[i].Value = int64(i)
-                                        if i == 4 {
-                                                fplss[i].IntID = int64(200)
-                                        }
-                                }
-                                So(ds.PutMulti(fplss), ShouldBeNil)
-                                for i, fpls := range fplss {
-                                        expect := int64(i + 1)
-                                        if i == 4 {
-                                                expect = 200
-                                        }
-                                        So(fpls.IntID, ShouldEqual, expect)
-                                }
-
-                                pm := PropertyMap{"Value": {MkProperty(0)}, "$kind": {MkPropertyNI("Pmap")}}
-                                So(ds.Put(pm), ShouldBeNil)
-                                So(ds.KeyForObj(pm).IntID(), ShouldEqual, 1)
-                        })
-
-                        Convey("[]P (map)", func() {
-                                pms := make([]PropertyMap, 7)
-                                for i := range pms {
-                                        pms[i] = PropertyMap{
-                                                "$kind": {MkProperty("Pmap")},
-                                                "Value": {MkProperty(i)},
-                                        }
-                                        if i == 4 {
-                                                So(pms[i].SetMeta("id", int64(200)), ShouldBeTrue)
-                                        }
-                                }
-                                So(ds.PutMulti(pms), ShouldBeNil)
-                                for i, pm := range pms {
-                                        expect := int64(i + 1)
-                                        if i == 4 {
-                                                expect = 200
-                                        }
-                                        So(ds.KeyForObj(pm).String(), ShouldEqual, fmt.Sprintf("s~aid:ns:/Pmap,%d", expect))
-                                }
-                        })
-
-                        Convey("[]*P", func() {
-                                fplss := make([]*FakePLS, 7)
-                                for i := range fplss {
-                                        fplss[i] = &FakePLS{Value: int64(i)}
-                                        if i == 4 {
-                                                fplss[i].IntID = int64(200)
-                                        }
-                                }
-                                So(ds.PutMulti(fplss), ShouldBeNil)
-                                for i, fpls := range fplss {
-                                        expect := int64(i + 1)
-                                        if i == 4 {
-                                                expect = 200
-                                        }
-                                        So(fpls.IntID, ShouldEqual, expect)
-                                }
-                        })
-
-                        Convey("[]*P (map)", func() {
-                                pms := make([]*PropertyMap, 7)
-                                for i := range pms {
-                                        pms[i] = &PropertyMap{
-                                                "$kind": {MkProperty("Pmap")},
-                                                "Value": {MkProperty(i)},
-                                        }
-                                        if i == 4 {
-                                                So(pms[i].SetMeta("id", int64(200)), ShouldBeTrue)
-                                        }
-                                }
-                                So(ds.PutMulti(pms), ShouldBeNil)
-                                for i, pm := range pms {
-                                        expect := int64(i + 1)
-                                        if i == 4 {
-                                                expect = 200
-                                        }
-                                        So(ds.KeyForObj(*pm).String(), ShouldEqual, fmt.Sprintf("s~aid:ns:/Pmap,%d", expect))
-                                }
-                        })
-
-                        Convey("[]I", func() {
-                                ifs := []interface{}{
-                                        &CommonStruct{Value: 0},
-                                        &FakePLS{Value: 1},
-                                        PropertyMap{"Value": {MkProperty(2)}, "$kind": {MkPropertyNI("Pmap")}},
-                                        &PropertyMap{"Value": {MkProperty(3)}, "$kind": {MkPropertyNI("Pmap")}},
-                                }
-                                So(ds.PutMulti(ifs), ShouldBeNil)
-                                for i := range ifs {
-                                        switch i {
-                                        case 0:
-                                                So(ifs[i].(*CommonStruct).ID, ShouldEqual, 1)
-                                        case 1:
-                                                fpls := ifs[i].(*FakePLS)
-                                                So(fpls.IntID, ShouldEqual, 2)
-                                        case 2:
-                                                So(ds.KeyForObj(ifs[i].(PropertyMap)).String(), ShouldEqual, "s~aid:ns:/Pmap,3")
-                                        case 3:
-                                                So(ds.KeyForObj(*ifs[i].(*PropertyMap)).String(), ShouldEqual, "s~aid:ns:/Pmap,4")
-                                        }
-                                }
-                        })
-
-                })
-
+                                So(func() { ds.PutMulti(&cs) }, ShouldPanicLike,
+                                        "argument must be a slice, not *datastore.CommonStruct")
+                        })
+
+                        Convey("Succeeds for a slice.", func() {
+                                cs := []CommonStruct{{Value: 0}, {Value: 1}}
+                                So(ds.PutMulti(cs), ShouldBeNil)
+                                So(cs[0].ID, ShouldEqual, 1)
+                                So(cs[1].ID, ShouldEqual, 2)
+                        })
+
+                        Convey("Returns an item error in a MultiError.", func() {
+                                cs := []FakePLS{{Value: 0}, {Kind: "Fail"}}
+                                err := ds.PutMulti(cs)
+                                So(err, ShouldResemble, errors.MultiError{nil, errFail})
+                                So(cs[0].IntID, ShouldEqual, 1)
+                        })
+                })
         })
 }
 
+func TestExists(t *testing.T) {
+        t.Parallel()
+
+        Convey("A testing environment", t, func() {
+                c := info.Set(context.Background(), fakeInfo{})
+                c = SetRawFactory(c, fakeDatastoreFactory)
+                ds := Get(c)
+
+                k := ds.MakeKey("Hello", "world")
+
+                Convey("Exists", func() {
+                        // Single key.
+                        er, err := ds.Exists(k)
+                        So(err, ShouldBeNil)
+                        So(er.All(), ShouldBeTrue)
+
+                        // Single key failure.
+                        _, err = ds.Exists(ds.MakeKey("Fail", "boom"))
+                        So(err, ShouldEqual, errFail)
+
+                        // Single slice of keys.
+                        er, err = ds.Exists([]*Key{k, ds.MakeKey("hello", "other")})
+                        So(err, ShouldBeNil)
+                        So(er.All(), ShouldBeTrue)
+
+                        // Single slice of keys failure.
+                        er, err = ds.Exists([]*Key{k, ds.MakeKey("Fail", "boom")})
+                        So(err, ShouldResemble, errors.MultiError{nil, errFail})
+                        So(er.Get(0, 0), ShouldBeTrue)
+
+                        // Single key missing.
+                        er, err = ds.Exists(ds.MakeKey("DNE", "nope"))
+                        So(err, ShouldBeNil)
+                        So(er.Any(), ShouldBeFalse)
+
+                        // Multi-arg keys with one missing.
+                        er, err = ds.Exists(k, ds.MakeKey("DNE", "other"))
+                        So(err, ShouldBeNil)
+                        So(er.Get(0), ShouldBeTrue)
+                        So(er.Get(1), ShouldBeFalse)
+
+                        // Multi-arg keys with two missing.
+                        er, err = ds.Exists(ds.MakeKey("DNE", "nope"), ds.MakeKey("DNE", "other"))
+                        So(err, ShouldBeNil)
+                        So(er.Any(), ShouldBeFalse)
+
+                        // Multi-arg mixed key/struct/slices.
+                        er, err = ds.Exists(&CommonStruct{ID: 1}, []*CommonStruct(nil), []*Key{ds.MakeKey("DNE", "nope"), ds.MakeKey("hello", "ohai")})
+                        So(err, ShouldBeNil)
+                        So(er.Get(0), ShouldBeTrue)
+                        So(er.Get(1), ShouldBeTrue)
+                        So(er.Get(2), ShouldBeFalse)
+                        So(er.Get(2, 0), ShouldBeFalse)
+                        So(er.Get(2, 1), ShouldBeTrue)
+                })
+
+                Convey("ExistsMulti", func() {
+                        Convey("Returns no error if there are no failures.", func() {
+                                bl, err := ds.ExistsMulti([]*Key{k, ds.MakeKey("DNE", "nope"), ds.MakeKey("hello", "ohai")})
+                                So(err, ShouldBeNil)
+                                So(bl, ShouldResemble, BoolList{true, false, true})
+                        })
+
+                        Convey("Returns an item error in a MultiError.", func() {
+                                _, err := ds.ExistsMulti([]*Key{k, ds.MakeKey("Fail", "boom")})
+                                So(err, ShouldResemble, errors.MultiError{nil, errFail})
+                        })
+                })
+        })
+}
+
 func TestDelete(t *testing.T) {
         t.Parallel()
 
-        Convey("Test Delete/DeleteMulti", t, func() {
+        Convey("A testing environment", t, func() {
                 c := info.Set(context.Background(), fakeInfo{})
                 c = SetRawFactory(c, fakeDatastoreFactory)
                 ds := Get(c)
                 So(ds, ShouldNotBeNil)
 
-                Convey("bad", func() {
-                        Convey("get single error for RPC failure", func() {
-                                keys := []*Key{
-                                        MakeKey("s~aid", "ns", "FailAll", 1),
-                                        MakeKey("s~aid", "ns", "Ok", 1),
-                                }
-                                So(ds.DeleteMulti(keys).Error(), ShouldEqual, "DeleteMulti fail all")
-                        })
-
-                        Convey("get multi error for individual failure", func() {
-                                keys := []*Key{
-                                        ds.MakeKey("Ok", 1),
-                                        ds.MakeKey("Fail", 2),
-                                }
-                                So(ds.DeleteMulti(keys).Error(), ShouldEqual, "DeleteMulti fail")
-                        })
-
-                        Convey("get single error when deleting a single", func() {
-                                k := ds.MakeKey("Fail", 1)
-                                So(ds.Delete(k).Error(), ShouldEqual, "DeleteMulti fail")
-                        })
-                })
-
+                Convey("Testing Delete", func() {
+                        Convey("bad", func() {
+                                Convey("get single error for RPC failure", func() {
+                                        keys := []*Key{
+                                                MakeKey("s~aid", "ns", "FailAll", 1),
+                                                MakeKey("s~aid", "ns", "Ok", 1),
+                                        }
+                                        So(ds.Delete(keys), ShouldEqual, errFailAll)
+                                })
+
+                                Convey("get multi error for individual failure", func() {
+                                        keys := []*Key{
+                                                ds.MakeKey("Ok", 1),
+                                                ds.MakeKey("Fail", 2),
+                                        }
+                                        So(ds.Delete(keys), ShouldResemble, errors.MultiError{nil, errFail})
+                                })
+
+                                Convey("get single error when deleting a single", func() {
+                                        k := ds.MakeKey("Fail", 1)
+                                        So(ds.Delete(k), ShouldEqual, errFail)
+                                })
+                        })
+
+                        Convey("good", func() {
+                                // Single struct.
+                                So(ds.Delete(&CommonStruct{ID: 1}), ShouldBeNil)
+
+                                // Single key.
+                                So(ds.Delete(ds.MakeKey("hello", "ohai")), ShouldBeNil)
+
+                                // Single struct DNE.
+                                So(ds.Delete(&CommonStruct{ID: noSuchEntityID}), ShouldEqual, ErrNoSuchEntity)
+
+                                // Single key DNE.
+                                So(ds.Delete(ds.MakeKey("DNE", "nope")), ShouldEqual, ErrNoSuchEntity)
+
+                                // Mixed key/struct/slices.
+                                err := ds.Delete(&CommonStruct{ID: 1}, []*Key{ds.MakeKey("hello", "ohai"), ds.MakeKey("DNE", "nope")})
+                                So(err, ShouldResemble, errors.MultiError{nil, errors.MultiError{nil, ErrNoSuchEntity}})
+                        })
+                })
+
+                Convey("Testing DeleteMulti", func() {
+                        Convey("Succeeds for valid keys.", func() {
+                                So(ds.DeleteMulti([]*Key{ds.MakeKey("hello", "ohai")}), ShouldBeNil)
+                                So(ds.DeleteMulti([]*Key{ds.MakeKey("hello", "ohai"), ds.MakeKey("hello", "sup")}), ShouldBeNil)
+                        })
+
+                        Convey("Returns an item error in a MultiError.", func() {
+                                So(ds.DeleteMulti([]*Key{ds.MakeKey("DNE", "oops")}), ShouldResemble, errors.MultiError{ErrNoSuchEntity})
+                        })
+                })
         })
 }
 
 func TestGet(t *testing.T) {
         t.Parallel()
 
-        Convey("Test Get/GetMulti", t, func() {
+        Convey("A testing environment", t, func() {
                 c := info.Set(context.Background(), fakeInfo{})
                 c = SetRawFactory(c, fakeDatastoreFactory)
                 ds := Get(c)
                 So(ds, ShouldNotBeNil)
 
-                Convey("bad", func() {
-                        Convey("static can't serialize", func() {
-                                toGet := []badStruct{{}, {}}
-                                So(func() { ds.GetMulti(toGet) }, ShouldPanicLike,
-                                        `field "Compy" has invalid type: complex64`)
-                        })
-
-                        Convey("can't get keys", func() {
-                                fplss := []FakePLS{{failGetMeta: true}, {}}
-                                So(ds.GetMulti(fplss), ShouldErrLike, "unable to extract $kind")
-                        })
-
-                        Convey("get single error for RPC failure", func() {
-                                fplss := []FakePLS{
-                                        {IntID: 1, Kind: "FailAll"},
-                                        {IntID: 2},
-                                }
-                                So(ds.GetMulti(fplss).Error(), ShouldEqual, "GetMulti fail all")
-                        })
-
-                        Convey("get multi error for individual failures", func() {
-                                fplss := []FakePLS{{IntID: 1}, {IntID: 2, Kind: "Fail"}}
-                                So(ds.GetMulti(fplss), ShouldResemble, errors.MultiError{nil, errors.New("GetMulti fail")})
-                        })
-
-                        Convey("get with non-modifiable type is an error", func() {
+                Convey("Testing Get", func() {
+                        Convey("bad", func() {
+                                Convey("static can't serialize", func() {
+                                        toGet := []badStruct{{}, {}}
+                                        So(func() { ds.Get(toGet) }, ShouldPanicLike,
+                                                `field "Compy" has invalid type: complex64`)
+                                })
+
+                                Convey("can't get keys", func() {
+                                        fplss := []FakePLS{{failGetMeta: true}, {}}
+                                        So(ds.Get(fplss), ShouldErrLike, "unable to extract $kind")
+                                })
+
+                                Convey("get single error for RPC failure", func() {
+                                        fplss := []FakePLS{
+                                                {IntID: 1, Kind: "FailAll"},
+                                                {IntID: 2},
+                                        }
+                                        So(ds.Get(fplss), ShouldEqual, errFailAll)
+                                })
+
+                                Convey("get multi error for individual failures", func() {
+                                        fplss := []FakePLS{{IntID: 1}, {IntID: 2, Kind: "Fail"}}
+                                        So(ds.Get(fplss), ShouldResemble, errors.MultiError{nil, errFail})
+                                })
+
+                                Convey("get with non-modifiable type is an error", func() {
+                                        cs := CommonStruct{}
+                                        So(func() { ds.Get(cs) }, ShouldPanicLike,
+                                                "invalid input type (datastore.CommonStruct): not a pointer")
+                                })
+
+                                Convey("get with nil is an error", func() {
+                                        So(func() { ds.Get(nil) }, ShouldPanicLike,
+                                                "cannot use nil as single argument")
+                                })
+
+                                Convey("get with ptr-to-nonstruct is an error", func() {
+                                        val := 100
+                                        So(func() { ds.Get(&val) }, ShouldPanicLike,
+                                                "invalid input type (*int): not a PLS or pointer-to-struct")
+                                })
+
+                                Convey("failure to save metadata is no problem though", func() {
+                                        // It just won't save the key
+                                        cs := &FakePLS{IntID: 10, failSetMeta: true}
+                                        So(ds.Get(cs), ShouldBeNil)
+                                })
+
+                                Convey("vararg with errors", func() {
+                                        successSlice := []CommonStruct{{ID: 1}, {ID: 2}}
+                                        failSlice := []CommonStruct{{ID: noSuchEntityID}, {ID: 3}}
+                                        emptySlice := []CommonStruct(nil)
+                                        cs0 := CommonStruct{ID: 4}
+                                        cs1 := CommonStruct{ID: noSuchEntityID}
+                                        fpls := FakePLS{StringID: "ohai"}
+
+                                        err := ds.Get(successSlice, failSlice, emptySlice, &cs0, &cs1, &fpls)
+                                        So(err, ShouldResemble, errors.MultiError{
+                                                nil, errors.MultiError{ErrNoSuchEntity, nil}, nil, nil, ErrNoSuchEntity, nil})
+                                        So(successSlice[0].Value, ShouldEqual, 1)
+                                        So(successSlice[1].Value, ShouldEqual, 2)
+                                        So(cs0.Value, ShouldEqual, 5)
+                                        So(fpls.Value, ShouldEqual, 7)
+                                })
+                        })
+
+                        Convey("ok", func() {
+                                Convey("Get", func() {
+                                        cs := &CommonStruct{ID: 1}
+                                        So(ds.Get(cs), ShouldBeNil)
+                                        So(cs.Value, ShouldEqual, 1)
+                                })
+
+                                Convey("Raw access too", func() {
+                                        rds := ds.Raw()
+                                        keys := []*Key{ds.MakeKey("Kind", 1)}
+                                        So(rds.GetMulti(keys, nil, func(pm PropertyMap, err error) error {
+                                                So(err, ShouldBeNil)
+                                                So(pm["Value"][0].Value(), ShouldEqual, 1)
+                                                return nil
+                                        }), ShouldBeNil)
+                                })
+
+                                Convey("but general failure to save is fine on a Get", func() {
+                                        cs := &FakePLS{failSave: true, IntID: 7}
+                                        So(ds.Get(cs), ShouldBeNil)
+                                })
+
+                                Convey("vararg", func() {
+                                        successSlice := []CommonStruct{{ID: 1}, {ID: 2}}
+                                        cs := CommonStruct{ID: 3}
+
+                                        err := ds.Get(successSlice, &cs)
+                                        So(err, ShouldBeNil)
+                                        So(successSlice[0].Value, ShouldEqual, 1)
+                                        So(successSlice[1].Value, ShouldEqual, 2)
+                                        So(cs.Value, ShouldEqual, 3)
+                                })
+                        })
+                })
+
+                Convey("Testing GetMulti", func() {
+                        Convey("Fails for something other than a slice.", func() {
                                 cs := CommonStruct{}
-                                So(func() { ds.Get(cs) }, ShouldPanicLike,
-                                        "invalid Get input type (datastore.CommonStruct): not a pointer")
-                        })
-
-                        Convey("get with nil is an error", func() {
-                                So(func() { ds.Get(nil) }, ShouldPanicLike,
-                                        "invalid Get input type (<nil>): no type information")
-                        })
-
-                        Convey("get with ptr-to-nonstruct is an error", func() {
-                                val := 100
-                                So(func() { ds.Get(&val) }, ShouldPanicLike,
-                                        "invalid Get input type (*int): does not point to a struct")
-                        })
-
-                        Convey("failure to save metadata is no problem though", func() {
-                                // It just won't save the key
-                                cs := &FakePLS{IntID: 10, failSetMeta: true}
-                                So(ds.Get(cs), ShouldBeNil)
-                        })
-                })
-
-                Convey("ok", func() {
-                        Convey("Get", func() {
-                                cs := &CommonStruct{ID: 1}
-                                So(ds.Get(cs), ShouldBeNil)
-                                So(cs.Value, ShouldEqual, 1)
-                        })
-
-                        Convey("Raw access too", func() {
-                                rds := ds.Raw()
-                                keys := []*Key{ds.MakeKey("Kind", 1)}
-                                So(rds.GetMulti(keys, nil, func(pm PropertyMap, err error) error {
-                                        So(err, ShouldBeNil)
-                                        So(pm["Value"][0].Value(), ShouldEqual, 1)
-                                        return nil
-                                }), ShouldBeNil)
-                        })
-
-                        Convey("but general failure to save is fine on a Get", func() {
-                                cs := &FakePLS{failSave: true, IntID: 7}
-                                So(ds.Get(cs), ShouldBeNil)
-                        })
-                })
-
+                                So(func() { ds.GetMulti(&cs) }, ShouldPanicLike,
+                                        "argument must be a slice, not *datastore.CommonStruct")
+                        })
+
+                        Convey("Succeeds for a slice.", func() {
+                                cs := []CommonStruct{{ID: 1}}
+                                So(ds.GetMulti(cs), ShouldBeNil)
+                                So(cs[0].Value, ShouldEqual, 1)
+                        })
+
+                        Convey("Returns an item error in a MultiError.", func() {
+                                cs := []CommonStruct{{ID: 1}, {ID: noSuchEntityID}}
+                                err := ds.GetMulti(cs)
+                                So(err, ShouldResemble, errors.MultiError{nil, ErrNoSuchEntity})
+                                So(cs[0].Value, ShouldEqual, 1)
+                        })
+                })
         })
 }
 
 func TestGetAll(t *testing.T) {
         t.Parallel()
 
         Convey("Test GetAll", t, func() {
                 c := info.Set(context.Background(), fakeInfo{})
                 c = SetRawFactory(c, fakeDatastoreFactory)
                 ds := Get(c)
@@ skipping 133 matching lines @@
 
                         Convey("interface", func() {
                                 assertBadTypePanics(func(pls PropertyLoadSaver) {})
                         })
 
                         Convey("bad proto type", func() {
                                 cb := func(v int) {
                                         panic("never here!")
                                 }
                                 So(func() { ds.Run(q, cb) }, ShouldPanicLike,
-                                        "invalid argument type: int")
+                                        "invalid argument type: int is not a PLS or pointer-to-struct")
                         })
 
                         Convey("wrong # args", func() {
                                 assertBadTypePanics(func(v CommonStruct, _ CursorCB, _ int) {
                                         panic("never here!")
                                 })
                         })
 
                         Convey("wrong ret type", func() {
                                 assertBadTypePanics(func(v CommonStruct) bool {
@@ skipping 650 matching lines @@
                         if err != nil {
                                 panic(fmt.Errorf("failed to find absolute path for `%s`", sameLevelDir))
                         }
 
                         ids, err := FindAndParseIndexYAML(abs)
                         So(err, ShouldBeNil)
                         So(ids[1].Kind, ShouldEqual, "Test Foo")
                 })
         })
 }