for _, tc := range toValidUTF8Tests {
		got := ToValidUTF8(tc.in, tc.repl)
		if got != tc.out {
			t.Errorf("ToValidUTF8(%q, %q) = %q; want %q", tc.in, tc.repl, got, tc.out)
		}
	}
}

func BenchmarkToUpper(b *testing.B) {
	for _, tc := range upperTests {
		b.Run(tc.in, func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				actual := ToUpper(tc.in)
				if actual != tc.out {

	}
}

func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTests) }

func TestToLower(t *testing.T) { runStringTests(t, ToLower, "ToLower", lowerTests) }

func BenchmarkToUpper(b *testing.B) {
	for _, tc := range upperTests {
		tin := []byte(tc.in)
		b.Run(tc.in, func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				actual := ToUpper(tin)
				if !Equal(actual, tc.out) {