Error Assertions

These assertions test Error objects and their properties.

to be an Error

Success:

expect(new Error(), 'to be an Error');
expect(new TypeError(), 'to be an Error');
expect(new RangeError('Invalid range'), 'to be an Error');
Copy

Failure:

expect('error message', 'to be an Error');
// AssertionError: Expected 'error message' to be an Error
Copy

Negation:

expect('error message', 'not to be an Error');
Copy

to have message <string>

Success:

const error = new Error('Something went wrong');
expect(error, 'to have message', 'Something went wrong');

const typeError = new TypeError('Invalid type');
expect(typeError, 'to have message', 'Invalid type');
Copy

Failure:

const error = new Error('Actual message');
expect(error, 'to have message', 'Expected message');
// AssertionError: Expected Error to have message 'Expected message'
Copy

Negation:

expect(error, 'not to have message', 'Expected message');
Copy

to have message matching <RegExp>

Success:

const error = new Error('File not found: /path/to/file.txt');
expect(error, 'to have message matching', /File not found/);
expect(error, 'to have message matching', /\.txt$/);
Copy

Failure:

const error = new Error('Something went wrong');
expect(error, 'to have message matching', /File not found/);
// AssertionError: Expected Error message to match /File not found/
Copy

Negation:

expect(error, 'not to have message matching', /File not found/);
Copy