feat: add generic copySlice function for pure package along with reve…

…rseSort helper function;

add tests that ensure the incoming slice is not mutated

pure/pure.go

@@ -0,0 +1,55 @@
+package pure
+
+import (
+	"sort"
+)
+
+type Item interface {
+	int | float64 | string
+}
+
+func reserveSort(x sort.Interface) {
+	sort.Sort(sort.Reverse(x))
+}
+
+func copySlice[I Item](original []I) []I {
+	c := make([]I, len(original))
+	copy(c, original)
+	return c
+}
+
+func NewSortedIntegers(ints []int) []int {
+	n := copySlice(ints)
+	sort.IntSlice(n).Sort()
+	return n
+}
+
+func NewSortedFloats(float64s []float64) []float64 {
+	n := copySlice(float64s)
+	sort.Float64Slice(n).Sort()
+	return n
+}
+
+func NewSortedStrings(strings []string) []string {
+	s := copySlice(strings)
+	sort.StringSlice(s).Sort()
+	return append(s)
+}
+
+func NewReverseSortedIntegers(integers []int) []int {
+	n := copySlice(integers)
+	reserveSort(sort.IntSlice(n))
+	return n
+}
+
+func NewReverseSortedFloats(float64s []float64) []float64 {
+	n := copySlice(float64s)
+	reserveSort(sort.Float64Slice(n))
+	return n
+}
+
+func NewReverseSortedStrings(strings []string) []string {
+	s := copySlice(strings)
+	reserveSort(sort.StringSlice(s))
+	return s
+}

sort/sort_test.go → pure/pure_test.go

@@ -1,49 +1,55 @@
-package sort_test
+package pure_test
 
 import (
-	csgo "github.com/cpustejovsky/customsortgo/sort"
+	"github.com/cpustejovsky/customsortgo/pure"
 	"github.com/stretchr/testify/assert"
 	"testing"
 )
 
 func TestSortForStrings(t *testing.T) {
 	w := []string{"cat", "albatross", "dolphin", "bee", "zebra", "aardvark"}
 	want := []string{"aardvark", "albatross", "bee", "cat", "dolphin", "zebra"}
-	got := csgo.NewSortedStrings(w)
+	got := pure.NewSortedStrings(w)
 	assert.Equal(t, want, got)
+	assert.NotEqual(t, got, w)
 }
 
 func TestReverseSortForStrings(t *testing.T) {
 	w := []string{"cat", "albatross", "dolphin", "bee", "zebra", "aardvark"}
 	want := []string{"zebra", "dolphin", "cat", "bee", "albatross", "aardvark"}
-	got := csgo.NewReverseSortedStrings(w)
+	got := pure.NewReverseSortedStrings(w)
 	assert.Equal(t, want, got)
+	assert.NotEqual(t, got, w)
 }
 
 func TestSortInts(t *testing.T) {
 	n := []int{1, 3, 5, 2, 7, 6, 4}
 	want := []int{1, 2, 3, 4, 5, 6, 7}
-	got := csgo.NewSortedIntegers(n)
+	got := pure.NewSortedIntegers(n)
 	assert.Equal(t, want, got)
+	assert.NotEqual(t, got, n)
 }
 
 func TestReverseSortInts(t *testing.T) {
 	n := []int{1, 3, 5, 2, 7, 6, 4}
 	want := []int{7, 6, 5, 4, 3, 2, 1}
-	got := csgo.NewReverseSortedIntegers(n)
+	got := pure.NewReverseSortedIntegers(n)
 	assert.Equal(t, want, got)
+	assert.NotEqual(t, got, n)
 }
 
 func TestSortFloat64s(t *testing.T) {
 	n := []float64{1.1, 3.3, 5.5, 2.2, 7.7, 6.6, 4.4}
 	want := []float64{1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7}
-	got := csgo.NewSortedFloats(n)
+	got := pure.NewSortedFloats(n)
 	assert.Equal(t, want, got)
+	assert.NotEqual(t, got, n)
 }
 
 func TestReverseSortFloat64s(t *testing.T) {
 	n := []float64{1.1, 3.3, 5.5, 2.2, 7.7, 6.6, 4.4}
 	want := []float64{7.7, 6.6, 5.5, 4.4, 3.3, 2.2, 1.1}
-	got := csgo.NewReverseSortedFloats(n)
+	got := pure.NewReverseSortedFloats(n)
 	assert.Equal(t, want, got)
+	assert.NotEqual(t, got, n)
 }