tidy: use strings.Cut over strings.IndexByte and manual slicing

Author: steverusso

cli_test.go

@@ -379,9 +379,9 @@ func TestParsing(t *testing.T) {
 			cmd: NewCmd("cp").
 				Opt(NewOpt("aa").
 					WithParser(func(s string) (any, error) {
-						comma := strings.IndexByte(s, ',')
-						x, _ := strconv.Atoi(s[:comma])
-						y, _ := strconv.Atoi(s[comma+1:])
+						xStr, yStr, _ := strings.Cut(s, ",")
+						x, _ := strconv.Atoi(xStr)
+						y, _ := strconv.Atoi(yStr)
 						return image.Point{X: x, Y: y}, nil
 					})),
 			variations: []testInputOutput{

examples_test.go

@@ -495,10 +495,12 @@ func ExampleInputInfo_ShortOnly() {
 }
 
 func ExampleInputInfo_WithParser() {
+	// This is a horrible parsing function for coordinates.
+	// It's just for example purposes.
 	pointParser := func(s string) (any, error) {
-		comma := strings.IndexByte(s, ',')
-		x, _ := strconv.Atoi(s[:comma])
-		y, _ := strconv.Atoi(s[comma+1:])
+		xStr, yStr, _ := strings.Cut(s, ",")
+		x, _ := strconv.Atoi(xStr)
+		y, _ := strconv.Atoi(yStr)
 		return image.Point{X: x, Y: y}, nil
 	}