fix: doc and tests

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

v2/readeroption/array_test.go

@@ -0,0 +1,107 @@
+// 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 readeroption
+
+import (
+	"context"
+	"testing"
+
+	A "github.com/IBM/fp-go/v2/array"
+	F "github.com/IBM/fp-go/v2/function"
+	O "github.com/IBM/fp-go/v2/option"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSequenceArray(t *testing.T) {
+
+	n := 10
+
+	readers := A.MakeBy(n, Of[context.Context, int])
+	exp := O.Of(A.MakeBy(n, F.Identity[int]))
+
+	g := F.Pipe1(
+		readers,
+		SequenceArray[context.Context, int],
+	)
+
+	assert.Equal(t, exp, g(context.Background()))
+}
+
+func TestTraverseArray(t *testing.T) {
+	// Function that doubles a number if it's positive
+	doubleIfPositive := func(x int) ReaderOption[context.Context, int] {
+		if x > 0 {
+			return Of[context.Context](x * 2)
+		}
+		return None[context.Context, int]()
+	}
+
+	// Test with all positive numbers
+	input1 := []int{1, 2, 3}
+	g1 := F.Pipe1(
+		Of[context.Context](input1),
+		Chain(TraverseArray[context.Context](doubleIfPositive)),
+	)
+	assert.Equal(t, O.Of([]int{2, 4, 6}), g1(context.Background()))
+
+	// Test with a negative number (should return None)
+	input2 := []int{1, -2, 3}
+	g2 := F.Pipe1(
+		Of[context.Context](input2),
+		Chain(TraverseArray[context.Context](doubleIfPositive)),
+	)
+	assert.Equal(t, O.None[[]int](), g2(context.Background()))
+
+	// Test with empty array
+	input3 := []int{}
+	g3 := F.Pipe1(
+		Of[context.Context](input3),
+		Chain(TraverseArray[context.Context](doubleIfPositive)),
+	)
+	assert.Equal(t, O.Of([]int{}), g3(context.Background()))
+}
+
+func TestTraverseArrayWithIndex(t *testing.T) {
+	// Function that multiplies value by its index if index is even
+	multiplyByIndexIfEven := func(idx int, x int) ReaderOption[context.Context, int] {
+		if idx%2 == 0 {
+			return Of[context.Context](x * idx)
+		}
+		return Of[context.Context](x)
+	}
+
+	input := []int{10, 20, 30, 40}
+	g := TraverseArrayWithIndex[context.Context](multiplyByIndexIfEven)(input)
+
+	// Expected: [10*0, 20, 30*2, 40] = [0, 20, 60, 40]
+	assert.Equal(t, O.Of([]int{0, 20, 60, 40}), g(context.Background()))
+}
+
+func TestTraverseArrayWithIndexNone(t *testing.T) {
+	// Function that returns None for odd indices
+	noneForOdd := func(idx int, x int) ReaderOption[context.Context, int] {
+		if idx%2 == 0 {
+			return Of[context.Context](x)
+		}
+		return None[context.Context, int]()
+	}
+
+	input := []int{10, 20, 30}
+	g := TraverseArrayWithIndex[context.Context](noneForOdd)(input)
+
+	// Should return None because index 1 returns None
+	assert.Equal(t, O.None[[]int](), g(context.Background()))
+}