fix(scanner): improve M3U playlist import times (#2706)

utils/slice/slice_test.go

@@ -1,15 +1,19 @@
 package slice_test
 
 import (
+	"os"
+	"slices"
 	"strconv"
 	"testing"
 
+	"github.com/navidrome/navidrome/tests"
 	"github.com/navidrome/navidrome/utils/slice"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 )
 
 func TestSlice(t *testing.T) {
+	tests.Init(t, false)
 	RegisterFailHandler(Fail)
 	RunSpecs(t, "Slice Suite")
 }
@@ -90,4 +94,32 @@ var _ = Describe("Slice Utils", func() {
 			Expect(chunks[1]).To(HaveExactElements("d", "e"))
 		})
 	})
+
+	DescribeTable("LinesFrom",
+		func(path string, expected int) {
+			count := 0
+			file, _ := os.Open(path)
+			defer file.Close()
+			for _ = range slice.LinesFrom(file) {
+				count++
+			}
+			Expect(count).To(Equal(expected))
+		},
+		Entry("returns empty slice for an empty input", "tests/fixtures/empty.txt", 0),
+		Entry("returns the lines of a file", "tests/fixtures/playlists/pls1.m3u", 3),
+		Entry("returns empty if file does not exist", "tests/fixtures/NON-EXISTENT", 0),
+	)
+
+	DescribeTable("CollectChunks",
+		func(input []int, n int, expected [][]int) {
+			result := [][]int{}
+			for chunks := range slice.CollectChunks[int](n, slices.Values(input)) {
+				result = append(result, chunks)
+			}
+			Expect(result).To(Equal(expected))
+		},
+		Entry("returns empty slice for an empty input", []int{}, 1, [][]int{}),
+		Entry("returns the slice in one chunk if len < chunkSize", []int{1, 2, 3}, 10, [][]int{{1, 2, 3}}),
+		Entry("breaks up the slice if len > chunkSize", []int{1, 2, 3, 4, 5}, 3, [][]int{{1, 2, 3}, {4, 5}}),
+	)
 })