bun:test/prefer-to-be-truthy

toBe(true) passes only for true itself. If the code returns 1, a string, or an object instead, the test fails, even though if (value) treats them all the same. toBeTruthy() passes for any truthy value.

toEqual(true) and toStrictEqual(true) are reported too, with or without .not.

--fix-suggestions replaces the matcher with toBeTruthy(). --fix doesn't, because the new matcher accepts more values.

Configure#

Off by default. To turn it on:

[lint.rules]
"bun:test/prefer-to-be-truthy" = "error" # or "warn"

Examples#

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

test("an admin can delete posts", () => {
  const user = createUser({ role: "admin" });
  expect(user.canDelete).toBe(true);
  expect(user.isBanned).not.toEqual(true);
});

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

test("an admin can delete posts", () => {
  const user = createUser({ role: "admin" });
  expect(user.canDelete).toBeTruthy();
  expect(user.isBanned).not.toBeTruthy();
});

When not to use it#

toBe(true) is the stricter check. If returning 1 or a string instead of true would be a bug, keep it. bun:test/prefer-strict-boolean-matchers is the opposite rule.