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no-weak-truthy-assertions

Disallow broad truthy and falsy assertions in executable tests.

Rule detailsโ€‹

toBeTruthy() and toBeFalsy() prove only JavaScript coercion behavior. They do not show whether the returned value is the expected boolean, object, array length, status code, or domain shape. A test can keep passing after the code starts returning the wrong truthy object or the wrong falsy value.

Incorrectโ€‹

it("returns a user", () => {
    expect(loadUser("abc")).toBeTruthy();
});
it("omits deleted users", () => {
    expect(loadUser("deleted")).toBeFalsy();
});

Correctโ€‹

it("returns a user", () => {
    expect(loadUser("abc")).toEqual({
        enabled: true,
        id: "abc",
    });
});
it("omits deleted users", () => {
    expect(loadUser("deleted")).toBeNull();
});

What this rule reportsโ€‹

This rule reports executable it(...) and test(...) callbacks that use:

  • expect(value).toBeTruthy()
  • expect(value).toBeFalsy()
  • negated or promise-modified forms such as not.toBeFalsy() and resolves.toBeTruthy()

Skipped and todo tests are left to no-disabled-tests.

Optionsโ€‹

This rule has no options.

When not to use itโ€‹

Disable this rule for compatibility tests that intentionally document JavaScript truthiness coercion. Product and library tests should usually assert exact booleans, nullish values, collection lengths, or object shapes.

Rule catalog ID: R011