add nop store

README.md

@@ -93,6 +93,8 @@ For the Godoc of specific implementations, see <https://pkg.go.dev/github.com/ph
     - [X] [Apache Ignite](https://github.com/apache/ignite)
     - [ ] [ArangoDB](https://github.com/arangodb/arangodb)
     - [ ] [OrientDB](https://github.com/orientechnologies/orientdb)
+- Misc
+    - [X] Go `nop` does nothing except validate the inputs, if applicable.
 
 Again:  
 For differences between the implementations, see [Choosing an implementation](docs/choosing-implementation.md).  

build/implementations

@@ -15,6 +15,7 @@ leveldb
 memcached
 mongodb
 mysql
+nop
 postgresql
 redis
 s3

docs/choosing-implementation.md

@@ -126,3 +126,5 @@ Implementations
     - [ArangoDB](https://github.com/arangodb/arangodb) (⚠️Not implemented yet!)
     - [OrientDB](https://github.com/orientechnologies/orientdb) (⚠️Not implemented yet!)
         - Claims to be the fastest graph database
+- Misc
+    - Go `nop` does nothing except validate the inputs, if applicable.

nop/docs.go

@@ -0,0 +1,4 @@
+/*
+Package nop contains an implementation of the `gokv.Store` interface that does nothing.
+*/
+package nop

nop/go.mod

@@ -0,0 +1,11 @@
+module github.com/philippgille/gokv/nop
+
+go 1.18
+
+require (
+	github.com/philippgille/gokv/util v0.6.0
+)
+
+require (
+	github.com/philippgille/gokv v0.6.0 // indirect
+)

nop/go.sum

@@ -0,0 +1,4 @@
+github.com/philippgille/gokv v0.6.0 h1:fNEx/tSwV73nzlYd3iRYB8F+SEVJNNFzH1gsaT8SK2c=
+github.com/philippgille/gokv v0.6.0/go.mod h1:tjXRFw9xDHgxLS8WJdfYotKGWp8TWqu4RdXjMDG/XBo=
+github.com/philippgille/gokv/util v0.6.0 h1:GrTxVENzKBxs8lB3tnaA88mKOuVPT7atZPplxX+PNmo=
+github.com/philippgille/gokv/util v0.6.0/go.mod h1:ovoDHZ2Svr7YX972SPPJQRXbhHEy3Gb20HRH/Tr9BiQ=

nop/nop.go

@@ -0,0 +1,43 @@
+package nop
+
+import "github.com/philippgille/gokv/util"
+
+// Store is a gokv.Store implementation that does nothing except validate the arguments if applicable.
+type Store struct{}
+
+// Set pretends if stores the key. Always return nil error unless the key or value are invalid.
+func (s Store) Set(k string, v interface{}) error {
+	if err := util.CheckKeyAndValue(k, v); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Get pretends it fetches the key. Always return not found and nil error unless the key or value are invalid.
+func (s Store) Get(k string, v interface{}) (found bool, err error) {
+	if err := util.CheckKeyAndValue(k, v); err != nil {
+		return false, err
+	}
+
+	return false, nil
+}
+
+// Delete pretends it deletes the key. Always return nil error unless the key is invalid.
+func (s Store) Delete(k string) error {
+	if err := util.CheckKey(k); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Close pretends it closes the store. Always return nil error.
+func (s Store) Close() error {
+	return nil
+}
+
+// NewStore creates a new nop Store that implements gokv.Store interface.
+func NewStore() Store {
+	return Store{}
+}

nop/nop_test.go

@@ -0,0 +1,89 @@
+package nop_test
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/philippgille/gokv"
+	"github.com/philippgille/gokv/nop"
+)
+
+func TestNop(t *testing.T) {
+	t.Parallel()
+
+	var s gokv.Store = nop.NewStore()
+
+	if err := s.Set("foo", 1); err != nil {
+		t.Error(err)
+	}
+
+	var v int
+	found, err := s.Get("foo", &v)
+	if err != nil {
+		t.Error(err)
+	}
+	if found {
+		t.Error("A value was found, but no value was expected")
+	}
+
+	if err := s.Delete("foo"); err != nil {
+		t.Error(err)
+	}
+
+	if err := s.Close(); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestInputValidation(t *testing.T) {
+	t.Parallel()
+
+	var s gokv.Store = nop.NewStore()
+
+	{
+		err := s.Set("", 1)
+		assertEqualError(t, err, errInvalidKey.Error())
+	}
+
+	{
+		err := s.Set("foo", nil)
+		assertEqualError(t, err, errInvalidValue.Error())
+	}
+
+	{
+		var v int
+		found, err := s.Get("", &v)
+		assertEqualError(t, err, errInvalidKey.Error())
+		if found {
+			t.Error("A value was found, but no value was expected")
+		}
+	}
+
+	{
+		found, err := s.Get("foo", nil)
+		assertEqualError(t, err, errInvalidValue.Error())
+		if found {
+			t.Error("A value was found, but no value was expected")
+		}
+	}
+
+	{
+		err := s.Delete("")
+		assertEqualError(t, err, errInvalidKey.Error())
+	}
+}
+
+func assertEqualError(t *testing.T, err error, expectedErrMsg string) {
+	t.Helper()
+
+	if err == nil {
+		t.Error("expect error, got nil")
+	} else if err.Error() != expectedErrMsg {
+		t.Error(err)
+	}
+}
+
+var (
+	errInvalidKey   = errors.New("The passed key is an empty string, which is invalid")
+	errInvalidValue = errors.New("The passed value is nil, which is not allowed")
+)