How to test the type of a thrown exception in Jest

Question

I\'m working with some code where I need to test the type of an exception thrown by a function (is it TypeError, ReferenceError, etc.?).

My current testing framework

Answer 1

In Jest you have to pass a function into expect(function).toThrow(blank or type of error).

Example:

test("Test description", () => {
  const t = () => {
    throw new TypeError();
  };
  expect(t).toThrow(TypeError);
});

If you need to test an existing function whether it throws with a set of arguments, you have to wrap it inside an anonymous function in expect().

Example:

test("Test description", () => {
  expect(() => {http.get(yourUrl, yourCallbackFn)}).toThrow(TypeError);
});