Improve format.Slice by special casing the first element (#183)

Author: FollowTheProcess

internal/format/format.go

@@ -107,18 +107,23 @@ func Slice[T any](s []T) string {
 
 	typ := reflect.TypeFor[T]().Kind()
 
-	for index, element := range s {
+	first := fmt.Sprintf("%v", s[0])
+	if typ == reflect.String {
+		first = strconv.Quote(first)
+	}
+
+	builder.WriteString(first)
+
+	for _, element := range s[1:] {
+		builder.WriteString(", ")
+
 		str := fmt.Sprintf("%v", element)
 		if typ == reflect.String {
 			// If it's a string, quote it
 			str = strconv.Quote(str)
 		}
 
 		builder.WriteString(str)
-
-		if index < length-1 {
-			builder.WriteString(", ")
-		}
 	}
 
 	builder.WriteByte(']')

internal/format/format_test.go

@@ -63,11 +63,15 @@ func TestFloat64(t *testing.T) {
 }
 
 func TestSlice(t *testing.T) {
+	oneString := []string{"one"}
+	twoStrings := []string{"one", "two"}
 	strings := []string{"one", "two", "three"}
 	ints := []int{1, 2, 3}
 	floats := []float64{1.0, 2.0, 3.0}
 	bools := []bool{true, true, false}
 
+	test.Equal(t, Slice(oneString), `["one"]`)
+	test.Equal(t, Slice(twoStrings), `["one", "two"]`)
 	test.Equal(t, Slice(strings), `["one", "two", "three"]`, test.Context("strings"))
 	test.Equal(t, Slice(ints), "[1, 2, 3]", test.Context("ints"))
 	test.Equal(t, Slice(floats), "[1, 2, 3]", test.Context("floats"))