This rule prevents the use of expect
inside catch
blocks.
Expectations inside a catch
block can be silently skipped. While Jest provides
an expect.assertions(number)
helper, it might be cumbersome to add this to
every single test. Using toThrow
concisely guarantees that an exception was
thrown, and that its contents match expectations.
The following patterns are warnings:
it('foo', () => {
try {
foo(); // `foo` may be refactored to not throw exceptions, yet still appears to be tested here.
} catch (err) {
expect(err).toMatch(/foo error/);
}
});
it('bar', async () => {
try {
await foo();
} catch (err) {
expect(err).toMatch(/foo error/);
}
});
it('baz', async () => {
try {
await foo();
} catch (err) {
expect(err).toMatchObject({ code: 'MODULE_NOT_FOUND' });
}
});
The following patterns are not warnings:
it('foo', () => {
expect(() => foo()).toThrow(/foo error/);
});
it('bar', async () => {
await expect(fooPromise).rejects.toThrow(/foo error/);
});
it('baz', async () => {
await expect(() => foo()).rejects.toThrow(
expect.objectContaining({ code: 'MODULE_NOT_FOUND' }),
);
});