func NewTrackingEventStore(appender eventstore.Appender) *TrackingEventStore {
	return &TrackingEventStore{Appender: appender}
}
NewTrackingEventStore wraps an Event Store to capture events that get
appended to it.
package inmemory
import (
	"context"
	"sync"
	"github.com/get-eventually/go-eventually"
	"github.com/get-eventually/go-eventually/eventstore"
	"github.com/get-eventually/go-eventually/eventstore/stream"
)
type TrackingEventStore struct {
	eventstore.Appender
	mx       sync.RWMutex
	recorded []eventstore.Event
}