Assertions

Assertions are built around expect(value, message?).

Basic examples:

expect(1 + 2).toBe(3);
expect("hello").toStartWith("he");
expect("world").toEndWith("ld");
expect(true).toBeTruthy();
expect(false).toBeFalsy();
expect(3.14159).toBeCloseTo(3.14, 2);
expect("abc123").toMatch("[a-z]+\\d+");

Negation:

expect(1).not.toBe(2);

Messages:

expect(total, "sum should stay stable").toBe(42);

Snapshot matcher:

expect(payload).toMatchSnapshot("payload");

Assertions inside fuzzers:

• they fail the fuzz iteration
• they do not count as normal test cases
• they are reported in the fuzz summary