I try to do this:

it('should throw an error', async ()=> {
    expect.assertions(1);
    try {
        await processor({}, MODULE_CONFIG)
    }
    catch (e) {
        expect(e).toBe("[TypeError: Cannot read properties of undefined (reading 'match')]")
    }
});

but it gives me this error:

I tried toMatch like in the docs, but it also give an error (one that seems even worse)

I tried using rejects.tobe instead, but i get the same error:

CodePudding user response：

Your problem is with what you are trying to assert

I'm assuming that you are throwing an error from processor

If you are, and you are asserting what that error is, keep in mind that typeof e === object, not string

For example:

function iThrownAnError() {
  throw new Error("ups");
}

describe("test a function that throws an error", () => {
  it("catches an error as expected", () => {
    try {
      iThrownAnError();
    } catch (e) {
      console.log(typeof e); // logs object
      console.log(typeof "ups"); // logs string

      // the test pass
      expect(e).toStrictEqual(new Error("ups"));

      // the test would fail
      // Expected: "ups"
      // Received: [Error: ups]
      expect(e).toStrictEqual("ups");
    }
  });
});

CodePudding user response：

The best answer I found seems to be getting the message property from the error (which is essentially just the error as a string), and comparing that.

expect(e.message).toBe("Cannot read properties of undefined (reading 'match')")