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amounts: more tests and closer behavior to reference impl

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This commit is contained in:
Florian Dold 2018-07-05 03:14:44 +02:00
parent 075fe28f74
commit 92843e3e92
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GPG Key ID: D2E4F00F29D02A4B
2 changed files with 70 additions and 29 deletions
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57
src/amounts.ts
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@ -38,6 +38,11 @@ export const fractionalBase = 1e8;
*/
export const fractionalLength = 8;
/**
* Maximum allowed value field of an amount.
*/
export const maxAmountValue = 2 ** 52;
/**
* Non-negative financial amount. Fractional values are expressed as multiples
@ -86,18 +91,6 @@ export interface Result {
}
/**
* Get the largest amount that is safely representable.
*/
export function getMaxAmount(currency: string): AmountJson {
return {
currency,
fraction: 2 ** 32,
value: Number.MAX_SAFE_INTEGER,
};
}
/**
* Get an amount that represents zero units of a currency.
*/
@ -120,8 +113,11 @@ export function getZero(currency: string): AmountJson {
export function add(first: AmountJson, ...rest: AmountJson[]): Result {
const currency = first.currency;
let value = first.value + Math.floor(first.fraction / fractionalBase);
if (value > Number.MAX_SAFE_INTEGER) {
return { amount: getMaxAmount(currency), saturated: true };
if (value > maxAmountValue) {
return {
amount: { currency, value: maxAmountValue, fraction: fractionalBase - 1 },
saturated: true
};
}
let fraction = first.fraction % fractionalBase;
for (const x of rest) {
@ -131,8 +127,11 @@ export function add(first: AmountJson, ...rest: AmountJson[]): Result {
value = value + x.value + Math.floor((fraction + x.fraction) / fractionalBase);
fraction = Math.floor((fraction + x.fraction) % fractionalBase);
if (value > Number.MAX_SAFE_INTEGER) {
return { amount: getMaxAmount(currency), saturated: true };
if (value > maxAmountValue) {
return {
amount: { currency, value: maxAmountValue, fraction: fractionalBase - 1 },
saturated: true
};
}
}
return { amount: { currency, value, fraction }, saturated: false };
@ -246,14 +245,22 @@ export function isNonZero(a: AmountJson): boolean {
* Parse an amount like 'EUR:20.5' for 20 Euros and 50 ct.
*/
export function parse(s: string): AmountJson|undefined {
const res = s.match(/([a-zA-Z0-9_*-]+):([0-9]+)([.][0-9]+)?/);
const res = s.match(/^([a-zA-Z0-9_*-]+):([0-9]+)([.][0-9]+)?$/);
if (!res) {
return undefined;
}
const tail = res[3] || ".0";
if (tail.length > fractionalLength + 1) {
return undefined;
}
let value = Number.parseInt(res[2]);
if (value > maxAmountValue) {
return undefined;
}
return {
currency: res[1],
fraction: Math.round(fractionalBase * Number.parseFloat(res[3] || "0")),
value: Number.parseInt(res[2]),
fraction: Math.round(fractionalBase * Number.parseFloat(tail)),
value,
};
}
@ -288,12 +295,14 @@ export function fromFloat(floatVal: number, currency: string) {
* Convert to standard human-readable string representation that's
* also used in JSON formats.
*/
export function toString(a: AmountJson) {
let s = a.value.toString()
export function toString(a: AmountJson): string {
const av = a.value + Math.floor(a.fraction / fractionalBase);
const af = a.fraction % fractionalBase;
let s = av.toString()
if (a.fraction) {
if (af) {
s = s + ".";
let n = a.fraction;
let n = af;
for (let i = 0; i < fractionalLength; i++) {
if (!n) {
break;
@ -310,7 +319,7 @@ export function toString(a: AmountJson) {
/**
* Check if the argument is a valid amount in string form.
*/
export function check(a: any) {
export function check(a: any): boolean {
if (typeof a !== "string") {
return false;
}

42
src/types-test.ts
View File

@ -30,7 +30,7 @@ test("amount addition (simple)", (t) => {
test("amount addition (saturation)", (t) => {
const a1 = amt(1, 0, "EUR");
const res = Amounts.add(Amounts.getMaxAmount("EUR"), a1);
const res = Amounts.add(amt(Amounts.maxAmountValue, 0, "EUR"), a1);
t.true(res.saturated);
t.pass();
});
@ -54,20 +54,52 @@ test("amount subtraction (saturation)", (t) => {
});
test("amount comparison", (t) => {
t.is(Amounts.cmp(amt(1, 0, "EUR"), amt(1, 0, "EUR")), 0);
t.is(Amounts.cmp(amt(1, 1, "EUR"), amt(1, 0, "EUR")), 1);
t.is(Amounts.cmp(amt(1, 1, "EUR"), amt(1, 2, "EUR")), -1);
t.is(Amounts.cmp(amt(1, 0, "EUR"), amt(0, 0, "EUR")), 1);
t.is(Amounts.cmp(amt(0, 0, "EUR"), amt(1, 0, "EUR")), -1);
t.is(Amounts.cmp(amt(1, 0, "EUR"), amt(0, 100000000, "EUR")), 0);
t.throws(() => Amounts.cmp(amt(1, 0, "FOO"), amt(1, 0, "BAR")));
t.pass();
});
test("amount parsing", (t) => {
const a1 = Amounts.parseOrThrow("TESTKUDOS:10");
t.is(a1.currency, "TESTKUDOS");
t.is(a1.value, 10);
t.is(a1.fraction, 0);
t.is(Amounts.cmp(Amounts.parseOrThrow("TESTKUDOS:0"),
amt(0, 0, "TESTKUDOS")), 0);
t.is(Amounts.cmp(Amounts.parseOrThrow("TESTKUDOS:10"),
amt(10, 0, "TESTKUDOS")), 0);
t.is(Amounts.cmp(Amounts.parseOrThrow("TESTKUDOS:0.1"),
amt(0, 10000000, "TESTKUDOS")), 0);
t.is(Amounts.cmp(Amounts.parseOrThrow("TESTKUDOS:0.00000001"),
amt(0, 1, "TESTKUDOS")), 0);
t.is(Amounts.cmp(Amounts.parseOrThrow("TESTKUDOS:4503599627370496.99999999"),
amt(4503599627370496, 99999999, "TESTKUDOS")), 0);
t.throws(() => Amounts.parseOrThrow("foo:"));
t.throws(() => Amounts.parseOrThrow("1.0"));
t.throws(() => Amounts.parseOrThrow("42"));
t.throws(() => Amounts.parseOrThrow(":1.0"));
t.throws(() => Amounts.parseOrThrow(":42"));
t.throws(() => Amounts.parseOrThrow("EUR:.42"));
t.throws(() => Amounts.parseOrThrow("EUR:42."));
t.throws(() => Amounts.parseOrThrow("TESTKUDOS:4503599627370497.99999999"));
t.is(Amounts.cmp(Amounts.parseOrThrow("TESTKUDOS:0.99999999"),
amt(0, 99999999, "TESTKUDOS")), 0);
t.throws(() => Amounts.parseOrThrow("TESTKUDOS:0.999999991"));
t.pass();
});
test("amount stringification", (t) => {
t.is(Amounts.toString(amt(0, 0, "TESTKUDOS")), "TESTKUDOS:0");
t.is(Amounts.toString(amt(4, 94000000, "TESTKUDOS")), "TESTKUDOS:4.94");
t.is(Amounts.toString(amt(0, 10000000, "TESTKUDOS")), "TESTKUDOS:0.1");
t.is(Amounts.toString(amt(0, 1, "TESTKUDOS")), "TESTKUDOS:0.00000001");
t.is(Amounts.toString(amt(5, 0, "TESTKUDOS")), "TESTKUDOS:5");
// denormalized
t.is(Amounts.toString(amt(1, 100000000, "TESTKUDOS")), "TESTKUDOS:2");
t.pass();
});