bun:test/no-restricted-matchers

Some matchers are too loose for your tests. toBeTruthy() passes for 1, "no" and [], so it doesn't prove that a value is true. This rule reports the matchers and modifiers you list.

Without options it reports nothing.

Configure#

Off by default. To turn it on:

bunfig.toml

[lint.rules]
"bun:test/no-restricted-matchers" = "error" # or "warn"

Examples#

bunfig.toml

[lint.rules]
"bun:test/no-restricted-matchers" = ["error", {
  toBeTruthy = "Use toBe(true) instead",
}]

example.tswith { "toBeTruthy": "Use toBe(true) instead" }1 problem

import { expect, test } from "bun:test";

test("a new user is active", () => {
  const user = { active: true };
  expect(user.active).toBeTruthy();
});

example.tswith { "toBeTruthy": "Use toBe(true) instead" }No problems

import { expect, test } from "bun:test";

test("a new user is active", () => {
  const user = { active: true };
  expect(user.active).toBe(true);
});

Options#

The rule takes one object. Each key is what you write after expect(..), joined with dots. Each value is a hint shown with the report, or "" for no hint. In bunfig.toml, put quotes around a key with a dot, like "not.toBe" = "".

Key	What it reports
A matcher, such as `"toBe"`	`expect(a).toBe(b)`, but not `expect(a).not.toBe(b)`.
A chain, such as `"not.toBe"`	`expect(a).not.toBe(b)`, but not `expect(a).toBe(b)`.
`"not"`, `"resolves"`, `"rejects"`, or a chain that ends in `.not`, such as `"resolves.not"`	Every chain that starts with it.

A matcher only matches when it's the whole chain, so { toBe = "" } allows this:

example.tswith { "toBe": "" }No problems

import { expect, test } from "bun:test";

test("ids differ", () => {
  expect(createId()).not.toBe(createId());
});

A modifier matches whatever comes after it. With { resolves = "" }, both lines are reported:

example.tswith { "resolves": "" }2 problems

import { expect, test } from "bun:test";

test("loads the user", async () => {
  await expect(loadUser(1)).resolves.toEqual({ id: 1 });
  await expect(loadUser(2)).resolves.not.toBeNull();
});