jest typescript test fetch
March 24th, 2023
example-service.ts
import { OktaAuth } from '@okta/okta-auth-js'
export interface FooData {
hello: string
}
export interface FooResult {
success: boolean
extraInfoForFrontend: string
}
export async function foo(oktaAuth: OktaAuth, data: FooData): Promise<FooResult> {
const accessToken = oktaAuth.getAccessToken()
try {
const response = await fetch("/foo", {
headers: {
Authorization: `Bearer ${accessToken}`,
},
})
const json = await response.json()
return {
success: true,
extraInfoForFrontend: json.message,
}
} catch (err) {
return {
success: false,
extraInfoForFrontend: 'Could not get data',
}
}
}
example-service.test.ts
import { foo } from './example-service'
import { OktaAuth } from '@okta/okta-auth-js'
const mockedFetchJson = jest.fn()
const mockedFetch = jest.fn(() =>
Promise.resolve({
json: mockedFetchJson,
})
) as any
type Fetch = (input: RequestInfo | URL, init?: RequestInit) => Promise<Response>
global.fetch = mockedFetch as Fetch
const ACCESS_TOKEN = "foo-access-token"
const oktaAuth = {
getAccessToken: () => ACCESS_TOKEN
} as any as OktaAuth // force typescript to accept it, event though the types don't match
const CONFIG_WITH_AUTH = {
headers: {
Authorization: `Bearer ${ACCESS_TOKEN}`,
},
}
beforeEach(() => {
mockedFetch.mockClear();
mockedFetchJson.mockClear();
});
describe('example-service', () => {
it('should return expected data', async () => {
mockedFetchJson.mockResolvedValue({message: "Message sent."})
const data = {hello: "foo"}
const response = await foo(oktaAuth, data)
expect(response).toEqual({
success: true,
extraInfoForFrontend: "Message sent."
})
expect(mockedFetch).toHaveBeenCalledTimes(1)
expect(mockedFetch).toHaveBeenCalledWith("/foo", CONFIG_WITH_AUTH)
expect(mockedFetchJson).toHaveBeenCalledTimes(1)
})
it('should handle failures', async ()=>{
mockedFetch.mockRejectedValue("Some network error occurred")
const data = {hello: "foo"}
const response = await foo(oktaAuth, data)
expect(response).toEqual({
success: false,
extraInfoForFrontend: "Could not get data"
})
expect(mockedFetch).toHaveBeenCalledTimes(1)
expect(mockedFetch).toHaveBeenCalledWith("/foo", CONFIG_WITH_AUTH)
expect(mockedFetchJson).not.toHaveBeenCalled()
})
})
inspiration