127 lines
4.5 KiB
Go
127 lines
4.5 KiB
Go
package common
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import (
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"math"
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"testing"
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"github.com/shopspring/decimal"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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)
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// 2000 quota per call * n=18446744073686646784 overflows int64; the constant
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// below reproduces that oversized product for the saturation checks.
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const overflowingProduct = 2000 * 1.8446744073686647e19
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// TestQuotaFromFloat guards the billing invariant that oversized quota
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// products (e.g. price multiplied by a huge user-supplied count) saturate
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// instead of wrapping into a negative charge (credit). QuotaFromFloat
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// truncates toward zero.
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func TestQuotaFromFloat(t *testing.T) {
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assert.Equal(t, 42, QuotaFromFloat(42.4))
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assert.Equal(t, 42, QuotaFromFloat(42.9))
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assert.Equal(t, -42, QuotaFromFloat(-42.9))
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assert.Equal(t, MaxQuota, QuotaFromFloat(overflowingProduct))
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assert.Equal(t, MinQuota, QuotaFromFloat(-overflowingProduct))
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assert.Equal(t, MaxQuota, QuotaFromFloat(math.Inf(1)))
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assert.Equal(t, MinQuota, QuotaFromFloat(math.Inf(-1)))
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assert.Equal(t, 0, QuotaFromFloat(math.NaN()))
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}
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// TestQuotaRound checks half-away-from-zero rounding with the same
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// saturation policy.
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func TestQuotaRound(t *testing.T) {
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assert.Equal(t, 42, QuotaRound(41.5))
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assert.Equal(t, 43, QuotaRound(42.5))
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assert.Equal(t, -43, QuotaRound(-42.5))
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assert.Equal(t, MaxQuota, QuotaRound(overflowingProduct))
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assert.Equal(t, MinQuota, QuotaRound(-overflowingProduct))
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assert.Equal(t, 0, QuotaRound(math.NaN()))
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}
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// TestQuotaFromDecimal checks the decimal entry point rounds and saturates
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// consistently with the float variants.
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func TestQuotaFromDecimal(t *testing.T) {
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assert.Equal(t, 43, QuotaFromDecimal(decimal.NewFromFloat(42.5)))
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assert.Equal(t, 42, QuotaFromDecimal(decimal.NewFromFloat(41.7)))
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assert.Equal(t, MaxQuota, QuotaFromDecimal(decimal.NewFromInt(2000).Mul(decimal.NewFromFloat(1.8446744073686647e19))))
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assert.Equal(t, MinQuota, QuotaFromDecimal(decimal.NewFromInt(-2000).Mul(decimal.NewFromFloat(1.8446744073686647e19))))
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}
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// TestQuotaFromFloatChecked verifies the clamp descriptor is nil in range and
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// carries the correct kind/clamped value on saturation, so billing callers can
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// audit the event.
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func TestQuotaFromFloatChecked(t *testing.T) {
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quota, clamp := QuotaFromFloatChecked(42.9)
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assert.Equal(t, 42, quota)
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assert.Nil(t, clamp)
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quota, clamp = QuotaFromFloatChecked(overflowingProduct)
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assert.Equal(t, MaxQuota, quota)
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if assert.NotNil(t, clamp) {
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assert.Equal(t, "QuotaFromFloat", clamp.Op)
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assert.Equal(t, QuotaClampOverflow, clamp.Kind)
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assert.Equal(t, MaxQuota, clamp.Clamped)
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}
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quota, clamp = QuotaFromFloatChecked(-overflowingProduct)
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assert.Equal(t, MinQuota, quota)
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if assert.NotNil(t, clamp) {
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assert.Equal(t, QuotaClampUnderflow, clamp.Kind)
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assert.Equal(t, MinQuota, clamp.Clamped)
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}
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quota, clamp = QuotaFromFloatChecked(math.NaN())
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assert.Equal(t, 0, quota)
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if assert.NotNil(t, clamp) {
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assert.Equal(t, QuotaClampNaN, clamp.Kind)
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assert.Equal(t, 0, clamp.Clamped)
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}
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}
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func TestQuotaFromFloatStrictReturnsTypedClampError(t *testing.T) {
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quota, err := QuotaFromFloatStrict(42.9)
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require.NoError(t, err)
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assert.Equal(t, 42, quota)
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quota, err = QuotaFromFloatStrict(overflowingProduct)
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assert.Zero(t, quota)
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var clamp *QuotaClamp
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require.ErrorAs(t, err, &clamp)
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assert.Equal(t, QuotaClampOverflow, clamp.Kind)
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assert.Equal(t, MaxQuota, clamp.Clamped)
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assert.ErrorContains(t, err, "QuotaFromFloat")
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assert.ErrorContains(t, err, "overflow")
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assert.ErrorContains(t, err, "original=")
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assert.ErrorContains(t, err, "clamped=2147483647")
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}
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// TestQuotaRoundChecked verifies the rounding entry point reports clamps the
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// same way.
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func TestQuotaRoundChecked(t *testing.T) {
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quota, clamp := QuotaRoundChecked(42.5)
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assert.Equal(t, 43, quota)
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assert.Nil(t, clamp)
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quota, clamp = QuotaRoundChecked(overflowingProduct)
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assert.Equal(t, MaxQuota, quota)
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if assert.NotNil(t, clamp) {
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assert.Equal(t, "QuotaRound", clamp.Op)
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assert.Equal(t, QuotaClampOverflow, clamp.Kind)
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}
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}
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// TestQuotaFromDecimalChecked verifies the decimal entry point reports clamps.
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func TestQuotaFromDecimalChecked(t *testing.T) {
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quota, clamp := QuotaFromDecimalChecked(decimal.NewFromFloat(41.7))
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assert.Equal(t, 42, quota)
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assert.Nil(t, clamp)
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quota, clamp = QuotaFromDecimalChecked(decimal.NewFromInt(2000).Mul(decimal.NewFromFloat(1.8446744073686647e19)))
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assert.Equal(t, MaxQuota, quota)
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if assert.NotNil(t, clamp) {
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assert.Equal(t, "QuotaFromDecimal", clamp.Op)
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assert.Equal(t, QuotaClampOverflow, clamp.Kind)
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}
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}
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