How to test a bad request in cypress

I am testing logging in POST method in cypress with incorrect credentials. this returns 400 bad requests which I need to test.

This is what I have:

    describe('Login API Test - Correct user login', () => {

it('Validate the header', () => {

    cy.request({
        method: 'POST',
        url: 'https://myrAPI',
        auth:
        {
            username: 'user@user',
            password: 'user123',
        },
        headers:
        {
            'Authorization': 'Basic dXNlckB1c2VyOnVzZXI=',
            'Content-Type': 'text/plain'
        }
    }).then((response) => {
        // expect(response.body).to.exist // true
        // expect(response.body).('User.Access: Exception occured:User.Access : CheckUser: Exception occurred:Error with Authentication Header. result =') // true
        // expect(response.headers).should.contain('text/plain; charset=utf-8')
        // expect(response.body).statusCode.should.equal(400)
        response.status.should.equal(400)
        //expect(response).to.have.property('headers')
    })

}})

This is the response I get:

    Error:     CypressError: cy.request() failed on:
    https://uafdiscdemo.azurewebsites.net/auth/Authorisation
    The response we received from your web server was:

400: Bad Request

This was considered a failure because the status code was not '2xx' or '3xx'.

If you do not want status codes to cause failures pass the option: 'failOnStatusCode: false'

---

The request we sent was:

Method: POST URL: https://uafdiscdemo.azurewebsites.net/auth/Authorisation Headers: { "Connection": "keep-alive", "Authorization": "Basic dXNlckB1c2VyOnVzZXIxMjM=", "Content-Type": "text/plain", "user-agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36", "accept": "/", "accept-encoding": "gzip, deflate", "content-length": 0 }

---

The response we got was:

Status: 400 - Bad Request Headers: { "content-length": "239", "content-type": "text/plain; charset=utf-8", "request-context": "appId=cid-v1:d994e38c-9493-4dd6-ac8c-5395bb9ce790", "date": "Tue, 02 Jul 2019 13:35:18 GMT" } Body: User.Access: Exception occured:User.Access : CheckUser: Exception occurred:Exception when checkin...