func TestDontLoopForever(t *testing.T) {
	s := NewScanner(strings.NewReader("abc"))
	s.Split(loopAtEOFSplit)
	// Expect a panic
	defer func() {
		err := recover()
		if err == nil {
			t.Fatal("should have panicked")
		}
		if msg, ok := err.(string); !ok || !strings.Contains(msg, "empty tokens") {
			panic(err)
		}
	}()
	for count := 0; s.Scan(); count++ {
		if count > 1000 {
			t.Fatal("looping")
		}
	}