How to assert that function throws with a specific error message

I’m using Node v18 ( with the built-in testrunner) and the package assert/strict to test that a function call throws an error with a custom error message.

I think my code should look like

assert.throws(() => myFunction(), 'content of error.message goes here');

Unfortunately I get the following error

error: ‘The “error/message” argument is ambiguous. The error message “content of error.message goes here” is identical to the message.’

I also tried

assert.throws(
  () => myFunction(), 
  error => {
    assert.ok(error instanceof CustomError);
    assert.strictEqual(error.message, 'content of error.message goes here');

    return true;
  });

and

assert.throws(myFunction, 'content of error.message goes here');

but unfortunately that didn’t help. This might be a duplicate of node assert: Test error message but I don’t want to pass in regular expressions because there is no need for it.

Does someone know how to fix the assertion?

Answer

From the docs, it looks like you can pass an object (and should for the OP case)…

// tests whether the thrown error has a particular message
assert.throws(myFunction, { message: 'content of error.message goes here'});