ts-prime/src/uniqBy.test.ts

A utility library for JavaScript and Typescript.

// import { uniq } from './uniq';
import { pipe } from './pipe';
import { createCounter } from './_counter';
import { take } from './take';
import { uniqBy } from './uniqBy';
import { identity } from './identity';

describe('uniqBy', () => {
  const people = [
    { name: 'John', age: 42 },
    { name: 'Jörn', age: 30 },
    { name: 'Sarah', age: 33 },
    { name: 'Kim', age: 22 },
    { name: 'Sarah', age: 38 },
    { name: 'John', age: 33 },
    { name: 'Emily', age: 42 },
  ] as const;

  it('handles uniq by identity', () => {
    expect(uniqBy([1, 2, 2, 5, 1, 6, 7], identity)).toEqual([1, 2, 5, 6, 7]);
  });

  it('returns people with uniq names', () => {
    expect(uniqBy(people, p => p.name)).toEqual([
      { name: 'John', age: 42 },
      { name: 'Jörn', age: 30 },
      { name: 'Sarah', age: 33 },
      { name: 'Kim', age: 22 },
      { name: 'Emily', age: 42 },
    ]);
  });

  it('returns people with uniq ages', () => {
    expect(uniqBy(people, p => p.age)).toEqual([
      { name: 'John', age: 42 },
      { name: 'Jörn', age: 30 },
      { name: 'Sarah', age: 33 },
      { name: 'Kim', age: 22 },
      { name: 'Sarah', age: 38 },
    ]);
  });

  it('returns people with uniq first letter of name', () => {
    expect(uniqBy(people, p => p.name.substring(0, 1))).toEqual([
      { name: 'John', age: 42 },
      { name: 'Sarah', age: 33 },
      { name: 'Kim', age: 22 },
      { name: 'Emily', age: 42 },
    ]);
  });

  describe('pipe', () => {
    it('gets executed until target length is reached', () => {
      const counter = createCounter();
      const result = pipe(
        [1, 2, 2, 5, 1, 6, 7],
        counter.fn(),
        uniqBy(identity),
        take(3)
      );

      expect(counter.count).toHaveBeenCalledTimes(4);
      expect(result).toEqual([1, 2, 5]);
    });

    it('get executed 3 times when take before uniqBy', () => {
      const counter = createCounter();
      const result = pipe(
        [1, 2, 2, 5, 1, 6, 7],
        counter.fn(),
        take(3),
        uniqBy(identity)
      );

      expect(counter.count).toHaveBeenCalledTimes(3);
      expect(result).toEqual([1, 2]);
    });
  });
});