chai test array equality doesn't work as expected

For expect, .equal will compare objects rather than their data, and in your case it is two different arrays.

Use .eql in order to deeply compare values. Check out this link.
Or you could use .deep.equal in order to simulate same as .eql.
Or in your case you might want to check .members.

For asserts you can use .deepEqual, link.

Try to use deep Equal. It will compare nested arrays as well as nested Json.

expect({ foo: 'bar' }).to.deep.equal({ foo: 'bar' });

Please refer to main documentation site.