// Make a string of all the runes.
	numRunes := int(unicode.MaxRune + 1)
	if testing.Short() {
		numRunes = 1000
	}
	a := make([]rune, numRunes)
	for i := range a {
		a[i] = rune(i)
	}
	s := string(a)
	// convert the cases.
	upper := ToUpper(s)
	lower := ToLower(s)

	// Consistency checks
	if n := utf8.RuneCountInString(upper); n != numRunes {
		t.Error("rune count wrong in upper:", n)

	instSize = 5 * 8 // byte, 2 uint32, slice is 5 64-bit words
)

// maxRunes is the maximum number of runes allowed in a regexp tree
// counting the runes in all the nodes.
// Ignoring character classes p.numRunes is always less than the length of the regexp.
// Character classes can make it much larger: each \pL adds 1292 runes.
// 128 MB is enough for 32M runes, which is over 26k \pL instances.