137 lines
3.3 KiB
Markdown
137 lines
3.3 KiB
Markdown
# Mocking Request
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Undici has its own mocking [utility](../api/MockAgent.md). It allow us to intercept undici HTTP requests and return mocked values instead. It can be useful for testing purposes.
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Example:
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```js
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// bank.mjs
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import { request } from 'undici'
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export async function bankTransfer(recipient, amount) {
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const { body } = await request('http://localhost:3000/bank-transfer',
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{
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method: 'POST',
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headers: {
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'X-TOKEN-SECRET': 'SuperSecretToken',
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},
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body: JSON.stringify({
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recipient,
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amount
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})
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}
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)
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return await body.json()
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}
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```
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And this is what the test file looks like:
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```js
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// index.test.mjs
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import { strict as assert } from 'assert'
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import { MockAgent, setGlobalDispatcher, } from 'undici'
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import { bankTransfer } from './bank.mjs'
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const mockAgent = new MockAgent();
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setGlobalDispatcher(mockAgent);
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// Provide the base url to the request
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const mockPool = mockAgent.get('http://localhost:3000');
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// intercept the request
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mockPool.intercept({
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path: '/bank-transfer',
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method: 'POST',
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headers: {
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'X-TOKEN-SECRET': 'SuperSecretToken',
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},
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body: JSON.stringify({
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recipient: '1234567890',
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amount: '100'
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})
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}).reply(200, {
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message: 'transaction processed'
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})
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const success = await bankTransfer('1234567890', '100')
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assert.deepEqual(success, { message: 'transaction processed' })
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// if you dont want to check whether the body or the headers contain the same value
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// just remove it from interceptor
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mockPool.intercept({
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path: '/bank-transfer',
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method: 'POST',
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}).reply(400, {
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message: 'bank account not found'
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})
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const badRequest = await bankTransfer('1234567890', '100')
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assert.deepEqual(badRequest, { message: 'bank account not found' })
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```
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Explore other MockAgent functionality [here](../api/MockAgent.md)
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## Debug Mock Value
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When the interceptor and the request options are not the same, undici will automatically make a real HTTP request. To prevent real requests from being made, use `mockAgent.disableNetConnect()`:
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```js
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const mockAgent = new MockAgent();
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setGlobalDispatcher(mockAgent);
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mockAgent.disableNetConnect()
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// Provide the base url to the request
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const mockPool = mockAgent.get('http://localhost:3000');
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mockPool.intercept({
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path: '/bank-transfer',
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method: 'POST',
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}).reply(200, {
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message: 'transaction processed'
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})
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const badRequest = await bankTransfer('1234567890', '100')
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// Will throw an error
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// MockNotMatchedError: Mock dispatch not matched for path '/bank-transfer':
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// subsequent request to origin http://localhost:3000 was not allowed (net.connect disabled)
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```
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## Reply with data based on request
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If the mocked response needs to be dynamically derived from the request parameters, you can provide a function instead of an object to `reply`:
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```js
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mockPool.intercept({
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path: '/bank-transfer',
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method: 'POST',
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headers: {
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'X-TOKEN-SECRET': 'SuperSecretToken',
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},
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body: JSON.stringify({
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recipient: '1234567890',
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amount: '100'
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})
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}).reply(200, (opts) => {
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// do something with opts
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return { message: 'transaction processed' }
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})
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```
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in this case opts will be
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```
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{
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method: 'POST',
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headers: { 'X-TOKEN-SECRET': 'SuperSecretToken' },
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body: '{"recipient":"1234567890","amount":"100"}',
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origin: 'http://localhost:3000',
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path: '/bank-transfer'
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}
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```
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