fix: add optics and consistent copyright

Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>

optics/optional/optional_test.go

@@ -0,0 +1,64 @@
+// Copyright (c) 2023 IBM Corp.
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package optional
+
+import (
+	"testing"
+
+	F "github.com/IBM/fp-go/function"
+	O "github.com/IBM/fp-go/option"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type (
+	Phone struct {
+		number string
+	}
+
+	Employment struct {
+		phone *Phone
+	}
+
+	Info struct {
+		employment *Employment
+	}
+
+	Response struct {
+		info *Info
+	}
+)
+
+func (response *Response) GetInfo() *Info {
+	return response.info
+}
+
+func (response *Response) SetInfo(info *Info) *Response {
+	response.info = info
+	return response
+}
+
+var (
+	responseOptional = FromPredicateRef[Response](F.IsNonNil[Info])((*Response).GetInfo, (*Response).SetInfo)
+
+	sampleResponse      = Response{info: &Info{}}
+	sampleEmptyResponse = Response{}
+)
+
+func TestOptional(t *testing.T) {
+	assert.Equal(t, O.Of(sampleResponse.info), responseOptional.GetOption(&sampleResponse))
+	assert.Equal(t, O.None[*Info](), responseOptional.GetOption(&sampleEmptyResponse))
+}