add utils.ChunkSlice (#23)

* add `utils.ChunkSlice`

* ensure test hits edge case

utils/chunk_slice.go

@@ -0,0 +1,14 @@
+package utils
+
+// ChunkSlice splits a slice into chunks of a given size.
+func ChunkSlice[T any](s []T, chunkSize int) [][]T {
+	var chunks [][]T
+	for i := 0; i < len(s); i += chunkSize {
+		end := i + chunkSize
+		if end > len(s) {
+			end = len(s)
+		}
+		chunks = append(chunks, s[i:end])
+	}
+	return chunks
+}

utils/chunk_slice_test.go

@@ -0,0 +1,24 @@
+package utils_test
+
+import (
+	"testing"
+
+	"github.com/aidenwallis/go-utils/internal/assert"
+	"github.com/aidenwallis/go-utils/utils"
+)
+
+func TestChunkSlice(t *testing.T) {
+	t.Parallel()
+
+	in := []int{1, 2, 3, 4, 5, 6, 7, 8}
+	expected := [][]int{{1, 2, 3}, {4, 5, 6}, {7, 8}}
+
+	out := utils.ChunkSlice(in, 3)
+
+	for i, chunk := range out {
+		assert.Equal(t, len(expected[i]), len(chunk))
+		for j, v := range chunk {
+			assert.Equal(t, expected[i][j], v)
+		}
+	}
+}