no-truthy-falsy.md

Disallow using toBeTruthy() & toBeFalsy() (no-truthy-falsy)

Tests against boolean values should assert true or false. Asserting toBeTruthy or toBeFalsy matches non-boolean values as well and encourages weaker tests.

For example, expect(someBoolean).toBeFalsy() passes when someBoolean === null, and when someBoolean === false.

Similarly, expect(someBoolean).toBeTruthy() passes when someBoolean === [], and when someBoolean === 'false' (note that 'false' is a string).

Rule details

This rule triggers a warning if toBeTruthy() or toBeFalsy() are used.

This rule is disabled by default.

Default configuration

The following patterns are considered warnings:

expect(someValue).toBeTruthy();
expect(someValue).toBeFalsy();

The following patterns are not considered warnings:

expect(someValue).toBe(true);
expect(someValue).toBe(false);