Enums

.toBeEnum(enum)

Also available as an asymmetric matcher, expect.ofEnum(enum).

Use .toBeEnum to assert that a value is a member of an enum (or const object).

enum Direction {
  Up,
  Down,
  Left,
  Right,
}

it("is a member of the numeric enum", () => {
  expect(Direction.Up).toBeEnum(Direction);
});

Tests

Aliasing expect.ofEnum to expect.enum

As enum is a reserved word in Javascript, it is not possible to export a matcher with this name. However, you can alias it in your setup file:

Jest

test-setup.ts

import { exactly, ofEnum } from "mix-n-matchers";
import type { MixNMatchersFrom, AsymmetricMixNMatchersFrom } from "mix-n-matchers";

const matchers = {
  exactly,
  enum: ofEnum,
};

expect.extend(matchers);

declare global {
  namespace jest {
    interface Matchers<R, T> extends MixNMatchersFrom<typeof matchers, R, T> {}

    interface Expect extends AsymmetricMixNMatchersFrom<typeof matchers> {
      enum: AsymmetricMatchers["ofEnum"];
    }

    interface InverseAsymmetricMatchers
      extends AsymmetricMixNMatchersFrom<typeof matchers> {
      enum: AsymmetricMatchers["ofEnum"];
    }
  }
}

Jest (no globals)

test-setup.ts

import { expect } from "@jest/globals";
import { exactly, ofEnum } from "mix-n-matchers";
import type { MixNMatchersFrom, AsymmetricMixNMatchersFrom } from "mix-n-matchers";

const matchers = {
  exactly,
  enum: ofEnum,
};

expect.extend(matchers);

declare module "@jest/expect" {
  interface Matchers<R, T> extends MixNMatchersFrom<typeof matchers, R, T> {}
  interface AsymmetricMatchers
    extends AsymmetricMixNMatchersFrom<typeof matchers> {
    enum: AsymmetricMatchers["ofEnum"];
  }
}

Vitest

test-setup.ts

import { expect } from "vitest";
import { exactly, ofEnum } from "mix-n-matchers";
import type { MixNMatchersFrom, AsymmetricMixNMatchersFrom } from "mix-n-matchers";

const matchers = {
  exactly,
  enum: ofEnum,
};

expect.extend(matchers);

declare module "vitest" {
  interface Assertion<T> extends MixNMatchersFrom<typeof matchers, void, T> {}
  interface AsymmetricMatchersContaining
    extends AsymmetricMixNMatchersFrom<typeof matchers> {
    enum: AsymmetricMatchers["ofEnum"];
  }
}

After this setup, you should be able to use expect.enum as a matcher.

expect(mock).toBeCalledWith(expect.enum(MyEnum));

This is automatically done for you with the auto-setup files.