Docs (4.0.0)
class Assertion property

not

Evaluates to a new negated assertion, where all methods mean the opposite of those on the current instance.

readonly

get not(): NegatedAssertion<T>

Example

// these are the same:
expect(1).toBeLessThan(2);
expect(1).not.toBeGreaterThanOrEqualTo(2);

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