Add jsdoc and unit tests for util functions

utils/array.test.ts

@@ -0,0 +1,130 @@
+import { describe, expect, it } from 'bun:test';
+import { multArray, multBy, sumArray, sumBy } from './array.ts';
+
+describe('array utils', () => {
+  it('sumArray number array', () => {
+    const array = [1, 2, 3];
+    const sum = sumArray(array);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(1 + 2 + 3);
+
+    expect(sumArray([])).toBeNumber();
+    expect(sumArray([])).toBeFinite();
+    expect(sumArray([])).toBe(0);
+  });
+  it('sumArray read-only number array', () => {
+    const array = [1, 2, 3] as const;
+    const sum = sumArray(array);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(1 + 2 + 3);
+
+    expect(sumArray([])).toBeNumber();
+    expect(sumArray([])).toBeFinite();
+    expect(sumArray([])).toBe(0);
+  });
+  it('sumBy number array', () => {
+    const array = [1, 2, 3];
+    const sum = sumBy(array, (e) => e);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(1 + 2 + 3);
+  });
+  it('sumBy read-only number array', () => {
+    const array = [1, 2, 3] as const;
+    const sum = sumBy(array, (e) => e);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(1 + 2 + 3);
+  });
+  it('sumBy mixed array', () => {
+    const array = [1, '2', 3.1, ''];
+
+    const sum = sumBy(array, (e) => e);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(1 + 2 + 3.1);
+  });
+  it('sumBy object array', () => {
+    const array: (
+      | { value: number | string }
+      | { differentValue: number | string }
+    )[] = [{ value: 3 }, { value: '2' }, { differentValue: '-2.44' }];
+
+    const sum = sumBy(array, (e) =>
+      'differentValue' in e ? e.differentValue : e.value
+    );
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(3 + 2 - 2.44);
+  });
+  it('sumBy empty array', () => {
+    expect(sumBy([], (e) => e)).toBeNumber();
+    expect(sumBy([], (e) => e)).toBeFinite();
+    expect(sumBy([], (e) => e)).toBe(0);
+  });
+
+  it('multArray number array', () => {
+    const array = [1, 2, 3];
+    const sum = multArray(array);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(2 * 3);
+
+    expect(multArray([])).toBeNumber();
+    expect(multArray([])).toBeFinite();
+    expect(multArray([])).toBe(0);
+  });
+  it('multArray read-only number array', () => {
+    const array = [1, 2, 3] as const;
+    const sum = multArray(array);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(2 * 3);
+
+    expect(multArray([])).toBeNumber();
+    expect(multArray([])).toBeFinite();
+    expect(multArray([])).toBe(0);
+  });
+  it('multBy number array', () => {
+    const array = [1, 2, 3];
+    const sum = sumBy(array, (e) => e);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(1 + 2 + 3);
+  });
+  it('multBy read-only number array', () => {
+    const array = [1, 2, 3] as const;
+    const sum = multBy(array, (e) => e);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(1 + 2 + 3);
+  });
+  it('multBy mixed array', () => {
+    const array = [1, '2', 3.1, ''];
+
+    const sum = multBy(array, (e) => e);
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(0);
+  });
+  it('multBy object array', () => {
+    const array: (
+      | { value: number | string }
+      | { differentValue: number | string }
+    )[] = [{ value: 3 }, { value: '2' }, { differentValue: '-2.44' }];
+
+    const sum = multBy(array, (e) =>
+      'differentValue' in e ? e.differentValue : e.value
+    );
+    expect(sum).toBeNumber();
+    expect(sum).toBeFinite();
+    expect(sum).toBe(3 * 2 * -2.44);
+  });
+  it('multBy empty array', () => {
+    expect(multBy([], (e) => e)).toBeNumber();
+    expect(multBy([], (e) => e)).toBeFinite();
+    expect(multBy([], (e) => e)).toBe(0);
+  });
+});

utils/array.ts

@@ -1,21 +1,41 @@
-export function sumArray(arr: Array<number>): number {
+/**
+ * Returns the sum of all the elements of a numeric array.
+ * @param arr Numeric array.
+ */
+export function sumArray(arr: ReadonlyArray<number>): number {
   return sumBy(arr, (a) => a);
 }
 
-export function sumBy<T>(
-  arr: Array<T>,
-  by: (array: T) => number | string
+/**
+ * Returns the sum of all the elements of any array,
+ * given a lamda function to receive the numeric representation of each element.
+ * @param arr Any array.
+ * @param by Map element to number or string, which will be interpreted as a number.
+ */
+export function sumBy<E>(
+  arr: ReadonlyArray<E>,
+  by: (element: E) => number | string
 ): number {
   return arr.reduce((sum, element) => sum + Number(by(element)), 0);
 }
 
-export function multArray(arr: Array<number>): number {
+/**
+ * Returns the product of a numeric array.
+ * @param arr Numeric array.
+ */
+export function multArray(arr: ReadonlyArray<number>): number {
   return multBy(arr, (a) => a);
 }
 
-export function multBy<T>(
-  arr: Array<T>,
-  by: (array: T) => number | string
+/**
+ * Returns the product of any array,
+ * given a lamda function to receive the numeric representation of each element.
+ * @param arr Any array.
+ * @param by Map element to number or string, which will be interpreted as a number.
+ */
+export function multBy<E>(
+  arr: ReadonlyArray<E>,
+  by: (element: E) => number | string
 ): number {
   if (arr.length <= 0) {
     return 0;
@@ -23,19 +43,28 @@ export function multBy<T>(
   return arr.reduce((sum, element) => sum * Number(by(element)), 1);
 }
 
+/**
+ * Group an array by a given key.
+ * @param arr Any array.
+ * @param by Map element to key.
+ * @param equals Check if two keys are identical. Defaults to strict equality.
+ */
 export function groupBy<E, K>(
-  arr: Array<E>,
-  by: (element: E) => K
+  arr: ReadonlyArray<E>,
+  by: (element: E) => K,
+  equals: (a: K, b: K) => boolean = (a, b) => a === b
 ): { key: K; elements: Array<E> }[] {
   return arr.reduce(
     (groups, element) => {
       const key = by(element);
-      const index = groups.findIndex((e) => e.key === key);
+      const index = groups.findIndex((e) => equals(e.key, key));
 
       if (index < 0) {
+        // New key found, add to group array.
         groups.push({ key, elements: [element] });
         return groups;
       }
+
       const existing = groups[index];
       existing.elements.push(element);
 

utils/random.test.ts

@@ -0,0 +1,17 @@
+import { describe, expect, it } from 'bun:test';
+import { randomInt } from './random.ts';
+
+describe('random utils', () => {
+  it('randomInt', () => {
+    const from = -2;
+    const to = 6;
+    for (let i = 0; i < 20; i++) {
+      const number = randomInt(from, to);
+      expect(number).toBeNumber();
+      expect(number).toBeFinite();
+      expect(number).toBeInteger();
+      expect(number).toBeGreaterThanOrEqual(from);
+      expect(number).toBeLessThan(to);
+    }
+  });
+});

utils/random.ts

@@ -1,3 +1,8 @@
+/**
+ * Returns a random integer between from and to, including from, excluding to.
+ * @param fromInclusive Lower bound, inclusive.
+ * @param toExclusive Upper Bound, exclusive.
+ */
 export function randomInt(fromInclusive: number, toExclusive: number): number {
   return (
     Math.floor(Math.random() * (toExclusive - fromInclusive)) + fromInclusive