test-randomizing

Helps you to build randomized objects for your tests.

🏗 Install

Deno (nest.land and deno.land)

import {
  freezeMerge,
  merge,
  RandomFn,
  freezeMergeFactory,
} from "https://x.nest.land/test_randomizing@0.5.0/mod.ts";
// or
import {
  freezeMerge,
  merge,
  RandomFn,
  freezeMergeFactory,
} from "https://deno.land/x/test_randomizing@0.5.0/mod.ts";

Node.js (npm.js)

npm install --save-dev test-randomizing
# or
yarn add --dev test-randomizing

🤷🏽‍♂️ How to use

You can use test randomizing in JavaScript and TypeScript projects.

We recommend using a library (like faker-js/faker or deno faker) to create randomized objects.

merge - merges two objects into one

function merge<T>(
  sourceObject: T,
  overrideObject?: DeepPartial<T>,
  options?: MergeOptions
): T;

// merges
merge({ sky: "blue", grass: "green" }, { sky: "red", sun: "yellow" });
// results in { sky: 'red', grass: 'green', sun: 'yellow'};

// merges deeply
merge(
  { grass: "green", sky: { night: "black", day: "grey" } },
  { sky: { day: "blue" } }
);
// results in { grass: 'green', sky: { night: 'black', day: 'grey' }};

// merges with undefined
merge({ sky: undefined, grass: "green" }, { sky: "blue", sun: undefined });
// results in { sky: 'blue', grass: 'green', sun: undefined };

freezeMerge - merges two objects into one and freezes the result

No diference to merge, only the result and all nested things are freezed with Object.freeze().

function freezeMerge<T>(source: T, override?: DeepPartial<T>): Readonly<T>;

// deep freezes the result
const freezedResult = freezeMerge({ sky: "blue" });
freezedResult.sky = "grey"; // change not possible
// results in { sky: 'blue' };

freezeMergeFactory - creates a function which is used to create overriden things via freeze merge

function freezeMergeFactory<T>(
  source: T
): (overrides?: DeepPartial<T>) => Readonly<T>;

// creates a, we call it 'random', function
const randomSky = freezeMergeFactory({ night: "black", day: "grey" });
randomSky({ day: "blue" });
// results in { night: 'black', day: 'blue };

Deno example - ./examples/deno:

import { freezeMergeFactory } from "https://x.nest.land/test_randomizing@0.5.0/mod.ts";
import { faker } from "https://deno.land/x/deno_faker@v1.0.3/mod.ts";
import { assertEquals } from "https://deno.land/std@0.119.0/testing/asserts.ts";

// Implementation
const generateEmail = (person: Person) => {
  if (!person.companyName || (!person.firstName && !person.lastName)) {
    return undefined;
  }

  return `${person.firstName}.${person.lastName}@${person.companyName}.com`;
};

// Types
type Person = {
  firstName: string;
  lastName: string;
  companyName: string;
};

// Test code
const randomPerson = freezeMergeFactory<Person>({
  firstName: faker.name.firstName(),
  lastName: faker.name.lastName(),
  companyName: faker.company.companyName(),
});

Deno.test("consist of firstname.lastname@companyname.com", () => {
  const person = randomPerson({
    firstName: "steve",
    lastName: "jobs",
    companyName: "apple",
  });

  const email = generateEmail(person);

  assertEquals(email, "steve.jobs@apple.com");
});

Deno.test("returns undefined if firstName and lastName is empty", () => {
  const person = randomPerson({ firstName: "", lastName: "" });

  const email = generateEmail(person);

  assertEquals(email, undefined);
});

Deno.test("returns undefined if companyName is empty", () => {
  const person = randomPerson({ companyName: "" });

  const email = generateEmail(person);

  assertEquals(email, undefined);
});

Typescript Node.js example - ./examples/nodejs-ts:

import { DeepPartial, freezeMerge, RandomFn } from "test-randomizing";
import { company, name } from "faker";

// Implementation
const generateEmail = (person: Person) => {
  if (!person.companyName || (!person.firstName && !person.lastName)) {
    return undefined;
  }

  return `${person.firstName}.${person.lastName}@${person.companyName}.com`;
};

// Types
type Person = {
  firstName: string;
  lastName: string;
  companyName: string;
};

// Test code
const randomPerson: RandomFn<Person> = (override?: DeepPartial<Person>) =>
  freezeMerge(
    {
      firstName: faker.name.firstName(),
      lastName: faker.name.lastName(),
      companyName: faker.company.companyName(),
    },
    override
  );

test("consist of firstname.lastname@companyname.com", () => {
  const person = randomPerson({
    firstName: "steve",
    lastName: "jobs",
    companyName: "apple",
  });

  const email = generateEmail(person);

  expect(email).toEqual("steve.jobs@apple.com");
});

test("returns undefined if firstName and lastName is empty", () => {
  const person = randomPerson({ firstName: "", lastName: "" });

  const email = generateEmail(person);

  expect(email).toBeUndefined();
});

test("returns undefined if companyName is empty", () => {
  const person = randomPerson({ companyName: "" });

  const email = generateEmail(person);

  expect(email).toBeUndefined();
});

More complete examples in the ./examples directory

• NodeJS TypeScript ./examples/nodejs-ts
• Deno ./examples/deno

License

MIT License

Copyright (c) 2021 Ti/o

Development

Use vr (Velociraptor) to run all commands like vr check and vr publish.