WIP mocking proof of concept

cluster.go

@@ -621,13 +621,13 @@ func (c *ClusterClient) Close() error {
 func (c *ClusterClient) Process(cmd Cmder) error {
 	state, err := c.state()
 	if err != nil {
-		cmd.setErr(err)
+		cmd.SetErr(err)
 		return err
 	}
 
 	_, node, err := c.cmdSlotAndNode(state, cmd)
 	if err != nil {
-		cmd.setErr(err)
+		cmd.SetErr(err)
 		return err
 	}
 

command.go

@@ -36,18 +36,18 @@ type Cmder interface {
 	Name() string
 
 	readReply(*pool.Conn) error
-	setErr(error)
 
 	readTimeout() *time.Duration
 
 	Err() error
+	SetErr(error)
 	fmt.Stringer
 }
 
 func setCmdsErr(cmds []Cmder, e error) {
 	for _, cmd := range cmds {
 		if cmd.Err() == nil {
-			cmd.setErr(e)
+			cmd.SetErr(e)
 		}
 	}
 }
@@ -154,7 +154,7 @@ func (cmd *baseCmd) setReadTimeout(d time.Duration) {
 	cmd._readTimeout = &d
 }
 
-func (cmd *baseCmd) setErr(e error) {
+func (cmd *baseCmd) SetErr(e error) {
 	cmd.err = e
 }
 
@@ -437,6 +437,10 @@ func NewStringCmd(args ...interface{}) *StringCmd {
 	}
 }
 
+func (cmd *StringCmd) SetVal(val string) {
+	cmd.val = []byte(val)
+}
+
 func (cmd *StringCmd) Val() string {
 	return internal.BytesToString(cmd.val)
 }

example_test.go

@@ -412,3 +412,26 @@ func ExampleNewUniversalClient_cluster() {
 
 	client.Ping()
 }
+
+func ExampleReplay() {
+	replay := redis.NewReplay()
+
+	cmd := redis.NewStringCmd("get", "foo")
+	cmd.SetVal("bar")
+	replay.Add(cmd)
+
+	cmd = redis.NewStringCmd("get", "hello")
+	cmd.SetErr(redis.Nil)
+	replay.Add(cmd)
+
+	client := redis.NewClient(&redis.Options{})
+	replay.WrapClient(client)
+
+	foo := client.Get("foo")
+	fmt.Println(foo)
+
+	hello := client.Get("hello")
+	fmt.Println(hello)
+	// Output: get foo: bar
+	// get hello: redis: nil
+}

redis.go

@@ -130,7 +130,7 @@ func (c *baseClient) defaultProcess(cmd Cmder) error {
 
 		cn, _, err := c.getConn()
 		if err != nil {
-			cmd.setErr(err)
+			cmd.SetErr(err)
 			if internal.IsRetryableError(err) {
 				continue
 			}
@@ -140,7 +140,7 @@ func (c *baseClient) defaultProcess(cmd Cmder) error {
 		cn.SetWriteTimeout(c.opt.WriteTimeout)
 		if err := writeCmd(cn, cmd); err != nil {
 			c.releaseConn(cn, err)
-			cmd.setErr(err)
+			cmd.SetErr(err)
 			if internal.IsRetryableError(err) {
 				continue
 			}

replay.go

@@ -0,0 +1,68 @@
+package redis
+
+import (
+	"fmt"
+	"reflect"
+)
+
+type replayAction struct {
+	cmd Cmder
+}
+
+type Replay struct {
+	actions []*replayAction
+}
+
+func NewReplay() *Replay {
+	return &Replay{}
+}
+
+func (r *Replay) Add(cmd Cmder) *Replay {
+	action := &replayAction{
+		cmd: cmd,
+	}
+	r.actions = append(r.actions, action)
+	return r
+}
+
+func (r *Replay) WrapClient(c *Client) {
+	c.WrapProcess(func(oldProcess func(cmd Cmder) error) func(cmd Cmder) error {
+		return r.process
+	})
+}
+
+func (r *Replay) process(cmd Cmder) error {
+	for _, a := range r.actions {
+		if argsEqual(cmd.args(), a.cmd.args()) {
+			if err := setCmd(cmd, a.cmd); err != nil {
+				return err
+			}
+			return cmd.Err()
+		}
+	}
+
+	cmd.SetErr(fmt.Errorf("unexpected cmd: %s", cmd))
+	return cmd.Err()
+}
+
+func argsEqual(a []interface{}, b []interface{}) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i, v := range a {
+		if v != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func setCmd(dst, src interface{}) error {
+	dstv := reflect.ValueOf(dst).Elem()
+	srcv := reflect.ValueOf(src).Elem()
+	if dstv.Type() != srcv.Type() {
+		return fmt.Errorf("dst and src commands have different types: %T and %T", dst, src)
+	}
+	dstv.Set(srcv)
+	return nil
+}

result.go

@@ -6,7 +6,7 @@ import "time"
 func NewCmdResult(val interface{}, err error) *Cmd {
 	var cmd Cmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -14,7 +14,7 @@ func NewCmdResult(val interface{}, err error) *Cmd {
 func NewSliceResult(val []interface{}, err error) *SliceCmd {
 	var cmd SliceCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -22,7 +22,7 @@ func NewSliceResult(val []interface{}, err error) *SliceCmd {
 func NewStatusResult(val string, err error) *StatusCmd {
 	var cmd StatusCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -30,7 +30,7 @@ func NewStatusResult(val string, err error) *StatusCmd {
 func NewIntResult(val int64, err error) *IntCmd {
 	var cmd IntCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -38,7 +38,7 @@ func NewIntResult(val int64, err error) *IntCmd {
 func NewDurationResult(val time.Duration, err error) *DurationCmd {
 	var cmd DurationCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -46,7 +46,7 @@ func NewDurationResult(val time.Duration, err error) *DurationCmd {
 func NewBoolResult(val bool, err error) *BoolCmd {
 	var cmd BoolCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -54,7 +54,7 @@ func NewBoolResult(val bool, err error) *BoolCmd {
 func NewStringResult(val string, err error) *StringCmd {
 	var cmd StringCmd
 	cmd.val = []byte(val)
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -62,7 +62,7 @@ func NewStringResult(val string, err error) *StringCmd {
 func NewFloatResult(val float64, err error) *FloatCmd {
 	var cmd FloatCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -70,7 +70,7 @@ func NewFloatResult(val float64, err error) *FloatCmd {
 func NewStringSliceResult(val []string, err error) *StringSliceCmd {
 	var cmd StringSliceCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -78,7 +78,7 @@ func NewStringSliceResult(val []string, err error) *StringSliceCmd {
 func NewBoolSliceResult(val []bool, err error) *BoolSliceCmd {
 	var cmd BoolSliceCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -86,7 +86,7 @@ func NewBoolSliceResult(val []bool, err error) *BoolSliceCmd {
 func NewStringStringMapResult(val map[string]string, err error) *StringStringMapCmd {
 	var cmd StringStringMapCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -94,7 +94,7 @@ func NewStringStringMapResult(val map[string]string, err error) *StringStringMap
 func NewStringIntMapCmdResult(val map[string]int64, err error) *StringIntMapCmd {
 	var cmd StringIntMapCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -102,7 +102,7 @@ func NewStringIntMapCmdResult(val map[string]int64, err error) *StringIntMapCmd
 func NewZSliceCmdResult(val []Z, err error) *ZSliceCmd {
 	var cmd ZSliceCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -111,7 +111,7 @@ func NewScanCmdResult(keys []string, cursor uint64, err error) *ScanCmd {
 	var cmd ScanCmd
 	cmd.page = keys
 	cmd.cursor = cursor
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -119,7 +119,7 @@ func NewScanCmdResult(keys []string, cursor uint64, err error) *ScanCmd {
 func NewClusterSlotsCmdResult(val []ClusterSlot, err error) *ClusterSlotsCmd {
 	var cmd ClusterSlotsCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -127,7 +127,7 @@ func NewClusterSlotsCmdResult(val []ClusterSlot, err error) *ClusterSlotsCmd {
 func NewGeoLocationCmdResult(val []GeoLocation, err error) *GeoLocationCmd {
 	var cmd GeoLocationCmd
 	cmd.locations = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }
 
@@ -135,6 +135,6 @@ func NewGeoLocationCmdResult(val []GeoLocation, err error) *GeoLocationCmd {
 func NewCommandsInfoCmdResult(val map[string]*CommandInfo, err error) *CommandsInfoCmd {
 	var cmd CommandsInfoCmd
 	cmd.val = val
-	cmd.setErr(err)
+	cmd.SetErr(err)
 	return &cmd
 }

ring.go

@@ -338,7 +338,7 @@ func (c *Ring) cmdShard(cmd Cmder) (*ringShard, error) {
 func (c *Ring) Process(cmd Cmder) error {
 	shard, err := c.cmdShard(cmd)
 	if err != nil {
-		cmd.setErr(err)
+		cmd.SetErr(err)
 		return err
 	}
 	return shard.Client.Process(cmd)