Custom Matchers
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π¨βπΌ Let's make our assertions better! We'll start with one called
toHaveRedirect which should replace our assertRedirect util. There are
really two checks going on here:- The response status code is between 300 and 400
- The
response.headers.get('location')is what we expect
So we should have three kinds of error messages:
Expected response to redirect but got no redirectExpected response status to be >= 300 && < 400 but got {status}Expected response to redirect to {expected} but got {actual}
And then if you have some extra time, you can try to support
expect(response).not.toHaveRedirect() which adds an interesting element to all
of this (can make the error message code look funny if you don't care about
ternaries π«’).Here's a reminder of what this API is like:
import {
expect,
type Assertion,
type AsymmetricMatchersContaining,
} from 'vitest'
expect.extend({
toBeLoggedIn(userName: string) {
const link = screen.queryByRole('link', { name: userName })
const button = screen.queryByRole('button', { name: /logout/i })
return {
pass: Boolean(link && button),
message: () => {
return `Expected ${
this.isNot ? 'not ' : ''
}to be logged in as ${this.utils.printExpected(userName)}`
},
}
},
})
interface CustomMatchers<R = unknown> {
toBeLoggedIn(userName: string): R
}
declare module 'vitest' {
interface Assertion<T = any> extends CustomMatchers<T> {}
interface AsymmetricMatchersContaining extends CustomMatchers {}
}
npx vitest auth
