test: Ensure return types of functions.

.eslintrc.js

@@ -12,7 +12,7 @@ module.exports = {
   rules: {
     'functional/no-conditional-statement': ['off'],
     'functional/functional-parameters': ['off'],
-    '@typescript-eslint/explicit-function-return-type': ['off'],
+    '@typescript-eslint/explicit-function-return-type': ['warn'],
     'valid-jsdoc': [
       'error',
       {

packages/calculator-bigint/package.json

@@ -29,7 +29,9 @@
   "module": "dist/esm/index.js",
   "source": "src/index.ts",
   "types": "dist/esm/index.d.ts",
-  "files": ["dist/"],
+  "files": [
+    "dist/"
+  ],
   "scripts": {
     "build:clean": "rimraf ./{dist,temp}",
     "build:esm": "babel src --root-mode upward --extensions '.ts' --out-dir dist/esm --ignore '**/*/__tests__/'",

packages/calculator-bigint/src/api/zero.ts

@@ -3,6 +3,6 @@
  *
  * @returns Zero as a bigint.
  */
-export function zero() {
+export function zero(): bigint {
   return 0n;
 }

packages/calculator-number/package.json

@@ -29,7 +29,9 @@
   "module": "dist/esm/index.js",
   "source": "src/index.ts",
   "types": "dist/esm/index.d.ts",
-  "files": ["dist/"],
+  "files": [
+    "dist/"
+  ],
   "scripts": {
     "build:clean": "rimraf ./{dist,temp}",
     "build:esm": "babel src --root-mode upward --extensions '.ts' --out-dir dist/esm --ignore '**/*/__tests__/'",

packages/calculator-number/src/api/zero.ts

@@ -3,6 +3,6 @@
  *
  * @returns Zero as a number.
  */
-export function zero() {
+export function zero(): number {
   return 0;
 }

packages/core/package.json

@@ -2,7 +2,12 @@
   "name": "@dinero.js/core",
   "version": "2.0.0-alpha.14",
   "description": "Common code between Dinero.js packages",
-  "keywords": ["money", "monetary", "amount", "immutable"],
+  "keywords": [
+    "money",
+    "monetary",
+    "amount",
+    "immutable"
+  ],
   "homepage": "https://v2.dinerojs.com",
   "bugs": "https://github.com/dinerojs/dinero.js/issues",
   "repository": {
@@ -22,7 +27,9 @@
   "module": "dist/esm/index.js",
   "source": "src/index.ts",
   "types": "dist/esm/index.d.ts",
-  "files": ["dist/"],
+  "files": [
+    "dist/"
+  ],
   "scripts": {
     "build:clean": "rimraf ./{dist,temp}",
     "build:esm": "babel src --root-mode upward --extensions '.ts' --out-dir dist/esm --ignore '**/*/__tests__/'",

packages/core/src/api/add.ts

@@ -12,7 +12,9 @@ export type AddParams<TAmount> = readonly [
 ];
 
 function unsafeAdd<TAmount>(calculator: Calculator<TAmount>) {
-  return function add(...[augend, addend]: AddParams<TAmount>) {
+  return function add(
+    ...[augend, addend]: AddParams<TAmount>
+  ): Dinero<TAmount> {
     const { amount: augendAmount, currency, scale } = augend.toJSON();
     const { amount: addendAmount } = addend.toJSON();
 
@@ -26,7 +28,9 @@ function unsafeAdd<TAmount>(calculator: Calculator<TAmount>) {
   };
 }
 
-export function safeAdd<TAmount>(calculator: Calculator<TAmount>) {
+export function safeAdd<TAmount>(
+  calculator: Calculator<TAmount>
+): (augend: Dinero<TAmount>, addend: Dinero<TAmount>) => Dinero<TAmount> {
   const normalizeFn = normalizeScale(calculator);
   const addFn = unsafeAdd(calculator);
 

packages/core/src/api/allocate.ts

@@ -21,7 +21,7 @@ type UnsafeAllocateParams<TAmount> = readonly [
 function unsafeAllocate<TAmount>(calculator: Calculator<TAmount>) {
   return function allocate(
     ...[dineroObject, ratios]: UnsafeAllocateParams<TAmount>
-  ) {
+  ): ReadonlyArray<Dinero<TAmount>> {
     const { amount, currency, scale } = dineroObject.toJSON();
     const distributeFn = distribute(calculator);
     const shares = distributeFn(
@@ -44,7 +44,12 @@ export type AllocateParams<TAmount> = readonly [
   ratios: ReadonlyArray<ScaledAmount<TAmount> | TAmount>
 ];
 
-export function safeAllocate<TAmount>(calculator: Calculator<TAmount>) {
+export function safeAllocate<TAmount>(
+  calculator: Calculator<TAmount>
+): (
+  dineroObject: Dinero<TAmount>,
+  ratios: ReadonlyArray<ScaledAmount<TAmount> | TAmount>
+) => ReadonlyArray<Dinero<TAmount>> {
   const allocateFn = unsafeAllocate(calculator);
   const greaterThanOrEqualFn = greaterThanOrEqual(calculator);
   const greaterThanFn = greaterThan(calculator);
@@ -58,12 +63,12 @@ export function safeAllocate<TAmount>(calculator: Calculator<TAmount>) {
     const hasRatios = ratios.length > 0;
     const scaledRatios = ratios.map((ratio) => getAmountAndScale(ratio, zero));
     const highestRatioScale = hasRatios
-      ? maximumFn(scaledRatios.map(({ scale }) => scale))
+      ? maximumFn(scaledRatios.map(({ scale }) => scale ?? zero))
       : zero;
     const normalizedRatios = scaledRatios.map(({ amount, scale }) => {
-      const factor = equalFn(scale, highestRatioScale)
+      const factor = equalFn(scale ?? zero, highestRatioScale)
         ? zero
-        : calculator.subtract(highestRatioScale, scale);
+        : calculator.subtract(highestRatioScale, scale ?? zero);
 
       return {
         amount: calculator.multiply(amount, calculator.power(ten, factor)),

packages/core/src/api/compare.ts

@@ -1,7 +1,7 @@
 /* eslint-disable functional/no-expression-statement */
 import { UNEQUAL_CURRENCIES_MESSAGE } from '../checks';
 import { assert } from '../helpers';
-import type { Calculator, Dinero } from '../types';
+import type { Calculator, ComparisonOperator, Dinero } from '../types';
 import { compare as cmp } from '../utils';
 
 import { haveSameCurrency } from './haveSameCurrency';
@@ -12,12 +12,17 @@ export type CompareParams<TAmount> = readonly [
   comparator: Dinero<TAmount>
 ];
 
-function unsafeCompare<TAmount>(calculator: Calculator<TAmount>) {
+function unsafeCompare<TAmount>(
+  calculator: Calculator<TAmount>
+): (
+  dineroObject: Dinero<TAmount>,
+  comparator: Dinero<TAmount>
+) => ComparisonOperator {
   const compareFn = cmp(calculator);
 
   return function compare(
     ...[dineroObject, comparator]: CompareParams<TAmount>
-  ) {
+  ): ComparisonOperator {
     const dineroObjects = [dineroObject, comparator];
 
     const [subjectAmount, comparatorAmount] = dineroObjects.map((d) => {
@@ -30,13 +35,18 @@ function unsafeCompare<TAmount>(calculator: Calculator<TAmount>) {
   };
 }
 
-export function safeCompare<TAmount>(calculator: Calculator<TAmount>) {
+export function safeCompare<TAmount>(
+  calculator: Calculator<TAmount>
+): (
+  dineroObject: Dinero<TAmount>,
+  comparator: Dinero<TAmount>
+) => ComparisonOperator {
   const normalizeFn = normalizeScale(calculator);
   const compareFn = unsafeCompare(calculator);
 
   return function compare(
     ...[dineroObject, comparator]: CompareParams<TAmount>
-  ) {
+  ): ComparisonOperator {
     const condition = haveSameCurrency([dineroObject, comparator]);
     assert(condition, UNEQUAL_CURRENCIES_MESSAGE);
 

packages/core/src/api/convert.ts

@@ -11,22 +11,28 @@ export type ConvertParams<TAmount> = readonly [
   rates: Rates<TAmount>
 ];
 
-export function convert<TAmount>(calculator: Calculator<TAmount>) {
+export function convert<TAmount>(
+  calculator: Calculator<TAmount>
+): (
+  dineroObject: Dinero<TAmount>,
+  newCurrency: Currency<TAmount>,
+  rates: Rates<TAmount>
+) => Dinero<TAmount> {
   const convertScaleFn = transformScale(calculator);
   const maximumFn = maximum(calculator);
   const zero = calculator.zero();
 
   return function convertFn(
     ...[dineroObject, newCurrency, rates]: ConvertParams<TAmount>
-  ) {
+  ): Dinero<TAmount> {
     const rate = rates[newCurrency.code];
     const { amount, scale } = dineroObject.toJSON();
     const { amount: rateAmount, scale: rateScale } = getAmountAndScale(
       rate,
       zero
     );
 
-    const newScale = calculator.add(scale, rateScale);
+    const newScale = calculator.add(scale, rateScale ?? zero);
 
     return convertScaleFn(
       dineroObject.create({

packages/core/src/api/equal.ts

@@ -9,7 +9,9 @@ export type EqualParams<TAmount> = readonly [
 ];
 
 export function equal<TAmount>(calculator: Calculator<TAmount>) {
-  return function _equal(...[dineroObject, comparator]: EqualParams<TAmount>) {
+  return function _equal(
+    ...[dineroObject, comparator]: EqualParams<TAmount>
+  ): boolean {
     return (
       haveSameAmount(calculator)([dineroObject, comparator]) &&
       haveSameCurrency([dineroObject, comparator])

packages/core/src/api/greaterThan.ts

@@ -12,12 +12,14 @@ export type GreaterThanParams<TAmount> = readonly [
   comparator: Dinero<TAmount>
 ];
 
-function unsafeGreaterThan<TAmount>(calculator: Calculator<TAmount>) {
+function unsafeGreaterThan<TAmount>(
+  calculator: Calculator<TAmount>
+): (dineroObject: Dinero<TAmount>, comparator: Dinero<TAmount>) => boolean {
   const greaterThanFn = gt(calculator);
 
   return function greaterThan(
     ...[dineroObject, comparator]: GreaterThanParams<TAmount>
-  ) {
+  ): boolean {
     const dineroObjects = [dineroObject, comparator];
 
     const [subjectAmount, comparatorAmount] = dineroObjects.map((d) => {
@@ -30,13 +32,15 @@ function unsafeGreaterThan<TAmount>(calculator: Calculator<TAmount>) {
   };
 }
 
-export function safeGreaterThan<TAmount>(calculator: Calculator<TAmount>) {
+export function safeGreaterThan<TAmount>(
+  calculator: Calculator<TAmount>
+): (dineroObject: Dinero<TAmount>, comparator: Dinero<TAmount>) => boolean {
   const normalizeFn = normalizeScale(calculator);
   const greaterThanFn = unsafeGreaterThan(calculator);
 
   return function greaterThan(
     ...[dineroObject, comparator]: GreaterThanParams<TAmount>
-  ) {
+  ): boolean {
     const condition = haveSameCurrency([dineroObject, comparator]);
     assert(condition, UNEQUAL_CURRENCIES_MESSAGE);
 

packages/core/src/api/greaterThanOrEqual.ts

@@ -12,12 +12,14 @@ export type GreaterThanOrEqualParams<TAmount> = readonly [
   comparator: Dinero<TAmount>
 ];
 
-function unsafeGreaterThanOrEqual<TAmount>(calculator: Calculator<TAmount>) {
+function unsafeGreaterThanOrEqual<TAmount>(
+  calculator: Calculator<TAmount>
+): (dineroObject: Dinero<TAmount>, comparator: Dinero<TAmount>) => boolean {
   const greaterThanOrEqualFn = gte(calculator);
 
   return function greaterThanOrEqual(
     ...[dineroObject, comparator]: GreaterThanOrEqualParams<TAmount>
-  ) {
+  ): boolean {
     const dineroObjects = [dineroObject, comparator];
 
     const [subjectAmount, comparatorAmount] = dineroObjects.map((d) => {
@@ -32,13 +34,13 @@ function unsafeGreaterThanOrEqual<TAmount>(calculator: Calculator<TAmount>) {
 
 export function safeGreaterThanOrEqual<TAmount>(
   calculator: Calculator<TAmount>
-) {
+): (dineroObject: Dinero<TAmount>, comparator: Dinero<TAmount>) => boolean {
   const normalizeFn = normalizeScale(calculator);
   const greaterThanOrEqualFn = unsafeGreaterThanOrEqual(calculator);
 
   return function greaterThanOrEqual(
     ...[dineroObject, comparator]: GreaterThanOrEqualParams<TAmount>
-  ) {
+  ): boolean {
     const condition = haveSameCurrency([dineroObject, comparator]);
     assert(condition, UNEQUAL_CURRENCIES_MESSAGE);
 

packages/core/src/api/hasSubUnits.ts

@@ -5,11 +5,15 @@ export type HasSubUnitsParams<TAmount> = readonly [
   dineroObject: Dinero<TAmount>
 ];
 
-export function hasSubUnits<TAmount>(calculator: Calculator<TAmount>) {
+export function hasSubUnits<TAmount>(
+  calculator: Calculator<TAmount>
+): (dineroObject: Dinero<TAmount>) => boolean {
   const equalFn = equal(calculator);
   const computeBaseFn = computeBase(calculator);
 
-  return function _hasSubUnits(...[dineroObject]: HasSubUnitsParams<TAmount>) {
+  return function _hasSubUnits(
+    ...[dineroObject]: HasSubUnitsParams<TAmount>
+  ): boolean {
     const { amount, currency, scale } = dineroObject.toJSON();
     const base = computeBaseFn(currency.base);
 

packages/core/src/api/haveSameAmount.ts

@@ -7,7 +7,9 @@ export type HaveSameAmountParams<TAmount> = readonly [
   dineroObjects: ReadonlyArray<Dinero<TAmount>>
 ];
 
-export function haveSameAmount<TAmount>(calculator: Calculator<TAmount>) {
+export function haveSameAmount<TAmount>(
+  calculator: Calculator<TAmount>
+): (dineroObjects: ReadonlyArray<Dinero<TAmount>>) => boolean {
   const normalizeFn = normalizeScale(calculator);
   const equalFn = equal(calculator);
 

packages/core/src/api/haveSameCurrency.ts

@@ -3,7 +3,7 @@ import { computeBase, equal } from '../utils';
 
 export function haveSameCurrency<TAmount>(
   dineroObjects: ReadonlyArray<Dinero<TAmount>>
-) {
+): boolean {
   const [firstDinero, ...otherDineros] = dineroObjects;
   const computeBaseFn = computeBase(firstDinero.calculator);
 

packages/core/src/api/isNegative.ts

@@ -5,10 +5,14 @@ export type IsNegativeParams<TAmount> = readonly [
   dineroObject: Dinero<TAmount>
 ];
 
-export function isNegative<TAmount>(calculator: Calculator<TAmount>) {
+export function isNegative<TAmount>(
+  calculator: Calculator<TAmount>
+): (dineroObject: Dinero<TAmount>) => boolean {
   const lessThanFn = lessThan(calculator);
 
-  return function _isNegative(...[dineroObject]: IsNegativeParams<TAmount>) {
+  return function _isNegative(
+    ...[dineroObject]: IsNegativeParams<TAmount>
+  ): boolean {
     const { amount } = dineroObject.toJSON();
 
     return lessThanFn(amount, calculator.zero());

packages/core/src/api/isPositive.ts

@@ -5,10 +5,14 @@ export type IsPositiveParams<TAmount> = readonly [
   dineroObject: Dinero<TAmount>
 ];
 
-export function isPositive<TAmount>(calculator: Calculator<TAmount>) {
+export function isPositive<TAmount>(
+  calculator: Calculator<TAmount>
+): (dineroObject: Dinero<TAmount>) => boolean {
   const greaterThanFn = greaterThan(calculator);
 
-  return function _isPositive(...[dineroObject]: IsPositiveParams<TAmount>) {
+  return function _isPositive(
+    ...[dineroObject]: IsPositiveParams<TAmount>
+  ): boolean {
     const { amount } = dineroObject.toJSON();
 
     return greaterThanFn(amount, calculator.zero());

packages/core/src/api/isZero.ts

@@ -3,10 +3,12 @@ import { equal } from '../utils';
 
 export type IsZeroParams<TAmount> = readonly [dineroObject: Dinero<TAmount>];
 
-export function isZero<TAmount>(calculator: Calculator<TAmount>) {
+export function isZero<TAmount>(
+  calculator: Calculator<TAmount>
+): (dineroObject: Dinero<TAmount>) => boolean {
   const equalFn = equal(calculator);
 
-  return function _isZero(...[dineroObject]: IsZeroParams<TAmount>) {
+  return function _isZero(...[dineroObject]: IsZeroParams<TAmount>): boolean {
     const { amount } = dineroObject.toJSON();
 
     return equalFn(amount, calculator.zero());