diff --git a/utils/slices_test.go b/utils/slices_test.go
new file mode 100644
index 00000000..afe1469f
--- /dev/null
+++ b/utils/slices_test.go
@@ -0,0 +1,110 @@
+package utils
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+)
+
+func TestFlatten(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		input    [][]int
+		expected []int
+	}{
+		{
+			name:     "nil slice",
+			input:    nil,
+			expected: nil,
+		},
+		{
+			name:     "empty slices",
+			input:    [][]int{{}},
+			expected: nil,
+		},
+		{
+			name:     "single slice",
+			input:    [][]int{{1, 2, 3}},
+			expected: []int{1, 2, 3},
+		},
+		{
+			name:     "multiple slices",
+			input:    [][]int{{1, 2}, {3, 4}, {5}},
+			expected: []int{1, 2, 3, 4, 5},
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			result := Flatten(tc.input...)
+			if !reflect.DeepEqual(result, tc.expected) {
+				t.Errorf("Flatten(%v) = %v, want %v", tc.input, result, tc.expected)
+			}
+		})
+	}
+}
+
+func TestMap(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		input    []int
+		expected []string
+	}{
+		{
+			name:     "empty slice",
+			input:    []int{},
+			expected: []string{},
+		},
+		{
+			name:     "non-empty slice",
+			input:    []int{1, 2, 3},
+			expected: []string{"1", "2", "3"},
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			result := Map(tc.input, func(i int) string { return fmt.Sprintf("%d", i) })
+			if !reflect.DeepEqual(result, tc.expected) {
+				t.Errorf("Map(%v) = %v, want %v", tc.input, result, tc.expected)
+			}
+		})
+	}
+}
+
+func TestFilter(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		input    []int
+		expected []int
+	}{
+		{
+			name:     "empty slice",
+			input:    []int{},
+			expected: []int{},
+		},
+		{
+			name:     "filter even numbers",
+			input:    []int{1, 2, 3, 4, 5},
+			expected: []int{2, 4},
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			result := Filter(tc.input, func(i int) bool { return i%2 == 0 })
+			if !reflect.DeepEqual(result, tc.expected) {
+				t.Errorf("Filter(%v) = %v, want %v", tc.input, result, tc.expected)
+			}
+		})
+	}
+}