Expect to throw

To check for exceptions, you'll need to both wrap the excepting function in a anonymous function, and use toThrow.

const iThrowErrors = () => {
    throw new Error("Oh NO!");
}

it("throws errors", () => {
    // This passes
    expect(() => iThrowErrors()).toThrow():

    // This also passes!
    expect(() => iThrowErrors()).toThrow("Oh NO!"):
})

See Jest .toThrow() expect documentation

Async functions that throw

If this is async, you'll need to chain a .rejects beforehand.

This makes the expect() return a Promise, which you'll need to await.

const iThrowErrorsAfterAWhile = async () => {
    throw new Error("OH NO! (after a while)");
}

it("throws errors, after a while", async () => {
    await expect(() => iThrowErrorsAfterAWhile()).rejects.toThrow();
})

See Jest rejects expect documentation