starlark/int_test.go

// Copyright 2017 The Bazel Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package starlark

import (
	"fmt"
	"math"
	"math/big"
	"testing"
)

// TestIntOpts exercises integer arithmetic, especially at the boundaries.
func TestIntOpts(t *testing.T) {
	f := MakeInt64
	left, right := big.NewInt(math.MinInt32), big.NewInt(math.MaxInt32)

	for i, test := range []struct {
		val  Int
		want string
	}{
		// Add
		{f(math.MaxInt32).Add(f(1)), "80000000"},
		{f(math.MinInt32).Add(f(-1)), "-80000001"},
		// Mul
		{f(math.MaxInt32).Mul(f(math.MaxInt32)), "3fffffff00000001"},
		{f(math.MinInt32).Mul(f(math.MinInt32)), "4000000000000000"},
		{f(math.MaxUint32).Mul(f(math.MaxUint32)), "fffffffe00000001"},
		{f(math.MinInt32).Mul(f(-1)), "80000000"},
		// Div
		{f(math.MinInt32).Div(f(-1)), "80000000"},
		{f(1 << 31).Div(f(2)), "40000000"},
		// And
		{f(math.MaxInt32).And(f(math.MaxInt32)), "7fffffff"},
		{f(math.MinInt32).And(f(math.MinInt32)), "-80000000"},
		{f(1 << 33).And(f(1 << 32)), "0"},
		// Mod
		{f(1 << 32).Mod(f(2)), "0"},
		// Or
		{f(1 << 32).Or(f(0)), "100000000"},
		{f(math.MaxInt32).Or(f(0)), "7fffffff"},
		{f(math.MaxUint32).Or(f(0)), "ffffffff"},
		{f(math.MinInt32).Or(f(math.MinInt32)), "-80000000"},
		// Xor
		{f(math.MinInt32).Xor(f(-1)), "7fffffff"},
		// Not
		{f(math.MinInt32).Not(), "7fffffff"},
		{f(math.MaxInt32).Not(), "-80000000"},
		// Shift
		{f(1).Lsh(31), "80000000"},
		{f(1).Lsh(32), "100000000"},
		{f(math.MaxInt32 + 1).Rsh(1), "40000000"},
		{f(math.MinInt32 * 2).Rsh(1), "-80000000"},
	} {
		if got := fmt.Sprintf("%x", test.val); got != test.want {
			t.Errorf("%d equals %s, want %s", i, got, test.want)
		}
		small, big := test.val.get()
		if small < math.MinInt32 || math.MaxInt32 < small {
			t.Errorf("expected big, %d %s", i, test.val)
		}
		if big == nil {
			continue
		}
		if small != 0 {
			t.Errorf("expected 0 small, %d %s with %d", i, test.val, small)
		}
		if big.Cmp(left) >= 0 && big.Cmp(right) <= 0 {
			t.Errorf("expected small, %d %s", i, test.val)
		}
	}
}

func TestImmutabilityMakeBigInt(t *testing.T) {
	// use max int64 for the test
	expect := int64(^uint64(0) >> 1)

	mutint := big.NewInt(expect)
	value := MakeBigInt(mutint)
	mutint.Set(big.NewInt(1))

	got, _ := value.Int64()
	if got != expect {
		t.Errorf("expected %d, got %d", expect, got)
	}
}

func TestImmutabilityBigInt(t *testing.T) {
	// use 1 and max int64 for the test
	for _, expect := range []int64{1, int64(^uint64(0) >> 1)} {
		value := MakeBigInt(big.NewInt(expect))

		bigint := value.BigInt()
		bigint.Set(big.NewInt(2))

		got, _ := value.Int64()
		if got != expect {
			t.Errorf("expected %d, got %d", expect, got)
		}
	}
}