Function TestNumDigitsLargeNegative

table_test.go:179–200

TestNumDigitsLargeNegative is a regression test for a bug where NumDigits would panic with a nil pointer dereference when processing large negative numbers (more than 128 bits). Seen in https://github.com/cockroachdb/cockroach/issues/165525.

(t *testing.T)

// numbers (more than 128 bits). Seen in
// https://github.com/cockroachdb/cockroach/issues/165525.
func TestNumDigitsLargeNegative(t *testing.T) {
	// Create a BigInt directly with more than 128 bits.
	var b BigInt
	b.SetInt64(2)
	exp := NewBigInt(200)
	b.Exp(&b, exp, nil)
	b.Neg(&b)

	numDigits := NumDigits(&b)
	// 2^200 has 61 decimal digits.
	expectedDigits := int64(61)
	if numDigits != expectedDigits {
		t.Errorf("expected %d digits, got %d", expectedDigits, numDigits)
	}

	// Also test via Decimal.
	d := NewWithBigInt(&b, 0)
	numDigits2 := d.NumDigits()
	if numDigits2 != expectedDigits {
		t.Errorf("expected %d digits via Decimal, got %d", expectedDigits, numDigits2)
	}
}