Install with your favorite package manager.
npm install mockemonyarn add mockemonbun add mockemonThe builder utility allows you to create strongly typed mocks for your tests, or anywhere else.
To use the builder, you must first configure it. This is done by importing and calling configureMockBuilder
import { configureMockBuilder } from "mockemon/builder";
import { faker } from "@faker-js/faker";
const createMockBuilder = configureMockBuilder({
// A value that will be passed as the argument to all mock builders.
// This is often a faker instance, but can be anything.
context: faker,
});Once the builder is configured, you can start creating mock builders.
const buildPetOwner = createMockBuilder((f) => ({
name: f.person.firstName(),
pet: f.animal.cat(),
}));The mock builder will automatically infer the type from the provided mock builder function.
const petOwner = buildPetOwner();
// { name: string, pet: string }Passing a value to the builder will override the default value.
const petOwner = buildPetOwner({
pet: "Daisy" as const,
});
// { name: string, pet: "Daisy" }It's also possible to pass a function to the builder. This function will be called with the provided faker instance, just like when setting up the builder initially.
const petOwner = buildPetOwner((f) => ({
pet: f.helpers.arrayElement(["Daisy", "Bella", "Luna"] as const]),
}));
// { name: string, pet: "Daisy" | "Bella" | "Luna" }The builder can also be used to mock other types of values as well, such as primitives or arrays.
// Mocks a string value
const buildName = createMockBuilder((f) => f.person.fullName);
const name1 = buildName();
const name2 = buildName("John Doe");
const name3 = buildName((f) => f.person.lastName());// Mocks an array
const buildNames = createMockBuilder((f) => {
return f.helpers.multiple(() => f.person.fullName());
});
const names1 = buildNames();
const names2 = buildNames(["John Doe", "Jane Doe"]);
const names3 = buildNames((f) => {
return f.helpers.multiple(() => f.person.lastName());
});If you have a value that that is a superset of another, you can reuse the builder of the subset in the builder of the superset by simply spreading it.
interface Person {
name: string;
age: number;
}
const buildPerson = createMockBuilder(
(f): Person => ({
name: f.person.firstName(),
age: f.random.number(),
}),
);
interface PetOwner extends Person {
pet: string;
}
const buildPetOwner = createMockBuilder(
(f): PetOwner => ({
...buildPerson(),
pet: f.animal.cat(),
}),
);const buildCatNames = createMockBuilder((f) => {
return f.helpers.shuffle(["Daisy", "Bella", "Luna"]);
});
const buildDogNames = createMockBuilder((f) => {
return f.helpers.shuffle(["Max", "Charlie", "Cooper"]);
});
const buildPets = createMockBuilder((f) => {
return f.helpers.shuffle([...buildCatNames(), ...buildDogNames()]);
});