fix: better package import

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

v2/samples/lens/example_test.go

@@ -0,0 +1,155 @@
+// Copyright (c) 2023 - 2025 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 lens
+
+import (
+	"testing"
+
+	F "github.com/IBM/fp-go/v2/function"
+	L "github.com/IBM/fp-go/v2/optics/lens"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPersonLens(t *testing.T) {
+	// Create a person
+	person := Person{
+		Name:  "Alice",
+		Age:   30,
+		Email: "alice@example.com",
+	}
+
+	// Create lenses
+	lenses := MakePersonLenses()
+
+	// Test Get
+	assert.Equal(t, "Alice", lenses.Name.Get(person))
+	assert.Equal(t, 30, lenses.Age.Get(person))
+	assert.Equal(t, "alice@example.com", lenses.Email.Get(person))
+
+	// Test Set
+	updated := lenses.Name.Set("Bob")(person)
+	assert.Equal(t, "Bob", updated.Name)
+	assert.Equal(t, 30, updated.Age)      // Other fields unchanged
+	assert.Equal(t, "Alice", person.Name) // Original unchanged
+
+	// Test Modify
+	incrementAge := F.Pipe1(
+		lenses.Age,
+		L.Modify[Person](func(age int) int { return age + 1 }),
+	)
+	incremented := incrementAge(person)
+	assert.Equal(t, 31, incremented.Age)
+	assert.Equal(t, 30, person.Age) // Original unchanged
+}
+
+func TestCompanyLens(t *testing.T) {
+	// Create a company with nested structures
+	company := Company{
+		Name: "Acme Corp",
+		Address: Address{
+			Street:  "123 Main St",
+			City:    "Springfield",
+			ZipCode: "12345",
+			Country: "USA",
+		},
+		CEO: Person{
+			Name:  "John Doe",
+			Age:   45,
+			Email: "john@acme.com",
+		},
+	}
+
+	// Create lenses
+	companyLenses := MakeCompanyLenses()
+	addressLenses := MakeAddressLenses()
+	personLenses := MakePersonLenses()
+
+	// Test simple field access
+	assert.Equal(t, "Acme Corp", companyLenses.Name.Get(company))
+
+	// Test nested field access using composition
+	cityLens := F.Pipe1(
+		companyLenses.Address,
+		L.Compose[Company](addressLenses.City),
+	)
+	assert.Equal(t, "Springfield", cityLens.Get(company))
+
+	// Test nested field update
+	updatedCompany := cityLens.Set("New York")(company)
+	assert.Equal(t, "New York", updatedCompany.Address.City)
+	assert.Equal(t, "Springfield", company.Address.City) // Original unchanged
+
+	// Test deeply nested field access
+	ceoNameLens := F.Pipe1(
+		companyLenses.CEO,
+		L.Compose[Company](personLenses.Name),
+	)
+	assert.Equal(t, "John Doe", ceoNameLens.Get(company))
+
+	// Test deeply nested field update
+	updatedCompany2 := ceoNameLens.Set("Jane Smith")(company)
+	assert.Equal(t, "Jane Smith", updatedCompany2.CEO.Name)
+	assert.Equal(t, "John Doe", company.CEO.Name) // Original unchanged
+}
+
+func TestLensComposition(t *testing.T) {
+	company := Company{
+		Name: "Tech Inc",
+		Address: Address{
+			Street:  "456 Oak Ave",
+			City:    "Boston",
+			ZipCode: "02101",
+			Country: "USA",
+		},
+		CEO: Person{
+			Name:  "Alice Johnson",
+			Age:   50,
+			Email: "alice@techinc.com",
+		},
+	}
+
+	companyLenses := MakeCompanyLenses()
+	personLenses := MakePersonLenses()
+
+	// Compose lenses to access CEO's email
+	ceoEmailLens := F.Pipe1(
+		companyLenses.CEO,
+		L.Compose[Company](personLenses.Email),
+	)
+
+	// Get the CEO's email
+	email := ceoEmailLens.Get(company)
+	assert.Equal(t, "alice@techinc.com", email)
+
+	// Update the CEO's email
+	updated := ceoEmailLens.Set("alice.johnson@techinc.com")(company)
+	assert.Equal(t, "alice.johnson@techinc.com", updated.CEO.Email)
+	assert.Equal(t, "alice@techinc.com", company.CEO.Email) // Original unchanged
+
+	// Modify the CEO's age
+	ceoAgeLens := F.Pipe1(
+		companyLenses.CEO,
+		L.Compose[Company](personLenses.Age),
+	)
+
+	modifyAge := F.Pipe1(
+		ceoAgeLens,
+		L.Modify[Company](func(age int) int { return age + 5 }),
+	)
+	olderCEO := modifyAge(company)
+	assert.Equal(t, 55, olderCEO.CEO.Age)
+	assert.Equal(t, 50, company.CEO.Age) // Original unchanged
+}