types(collection): reduce* method signatures (#10405)

* types(collection): reduce* method signatures

* test: explicit expect() types

* test: add tests for arbitrary accumulator type

---------

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
This commit is contained in:
René
2024-07-28 14:37:45 +01:00
committed by GitHub
parent bf6761a44a
commit 6b383350a6
2 changed files with 62 additions and 31 deletions

View File

@@ -713,14 +713,57 @@ describe('reduce() tests', () => {
expect<number>(sum).toStrictEqual(6);
});
test('reduce collection into a single value with different accumulator type', () => {
const str = coll.reduce((a, x) => a.concat(x.toString()), '');
expect<string>(str).toStrictEqual('123');
});
test('reduce empty collection with initial value', () => {
const coll = createCollection();
expect(coll.reduce((a, x) => a + x, 0)).toStrictEqual(0);
expect<number>(coll.reduce((a, x) => a + x, 0)).toStrictEqual(0);
});
test('reduce empty collection without initial value', () => {
const coll = createCollection();
expect(() => coll.reduce((a: number, x) => a + x)).toThrowError(
expect(() => coll.reduce((a, x) => a + x)).toThrowError(
new TypeError('Reduce of empty collection with no initial value'),
);
});
});
describe('reduceRight() tests', () => {
const coll = createTestCollection();
test('throws if fn is not a function', () => {
// @ts-expect-error: Invalid function
expectInvalidFunctionError(() => coll.reduceRight());
// @ts-expect-error: Invalid function
expectInvalidFunctionError(() => coll.reduceRight(123), 123);
});
test('reduce collection into a single value with initial value', () => {
const sum = coll.reduceRight((a, x) => a + x, 0);
expect<number>(sum).toStrictEqual(6);
});
test('reduce collection into a single value without initial value', () => {
const sum = coll.reduceRight((a, x) => a + x);
expect<number>(sum).toStrictEqual(6);
});
test('reduce collection into a single value with different accumulator type', () => {
const str = coll.reduceRight((a, x) => a.concat(x.toString()), '');
expect<string>(str).toStrictEqual('321');
});
test('reduce empty collection with initial value', () => {
const coll = createCollection();
expect<number>(coll.reduceRight((a, x) => a + x, 0)).toStrictEqual(0);
});
test('reduce empty collection without initial value', () => {
const coll = createCollection();
expect(() => coll.reduceRight((a, x) => a + x)).toThrowError(
new TypeError('Reduce of empty collection with no initial value'),
);
});
@@ -1013,31 +1056,3 @@ describe('findLastKey() tests', () => {
}, null);
});
});
describe('reduceRight() tests', () => {
const coll = createTestCollection();
test('throws if fn is not a function', () => {
// @ts-expect-error: Invalid function
expectInvalidFunctionError(() => coll.reduceRight());
// @ts-expect-error: Invalid function
expectInvalidFunctionError(() => coll.reduceRight(123), 123);
});
test('reduce collection into a single value with initial value', () => {
const sum = coll.reduceRight((a, x) => a + x, 0);
expect(sum).toStrictEqual(6);
});
test('reduce collection into a single value without initial value', () => {
const sum = coll.reduceRight<number>((a, x) => a + x);
expect(sum).toStrictEqual(6);
});
test('reduce empty collection without initial value', () => {
const coll = createCollection();
expect(() => coll.reduceRight((a: number, x) => a + x)).toThrowError(
new TypeError('Reduce of empty collection with no initial value'),
);
});
});

View File

@@ -616,7 +616,15 @@ export class Collection<Key, Value> extends Map<Key, Value> {
* collection.reduce((acc, guild) => acc + guild.memberCount, 0);
* ```
*/
public reduce<InitialValue = Value>(
public reduce(
fn: (accumulator: Value, value: Value, key: Key, collection: this) => Value,
initialValue?: Value,
): Value;
public reduce<InitialValue>(
fn: (accumulator: InitialValue, value: Value, key: Key, collection: this) => InitialValue,
initialValue: InitialValue,
): InitialValue;
public reduce<InitialValue>(
fn: (accumulator: InitialValue, value: Value, key: Key, collection: this) => InitialValue,
initialValue?: InitialValue,
): InitialValue {
@@ -645,6 +653,14 @@ export class Collection<Key, Value> extends Map<Key, Value> {
* @param fn - Function used to reduce, taking four arguments; `accumulator`, `value`, `key`, and `collection`
* @param initialValue - Starting value for the accumulator
*/
public reduceRight(
fn: (accumulator: Value, value: Value, key: Key, collection: this) => Value,
initialValue?: Value,
): Value;
public reduceRight<InitialValue>(
fn: (accumulator: InitialValue, value: Value, key: Key, collection: this) => InitialValue,
initialValue: InitialValue,
): InitialValue;
public reduceRight<InitialValue>(
fn: (accumulator: InitialValue, value: Value, key: Key, collection: this) => InitialValue,
initialValue?: InitialValue,