Automatically generate and use network request mocks inside Playwright!
Mocking your API requests takes too much precious development time, this library strives to make it effortless by:
npm install playwright-request-mocker -D
yarn add playwright-request-mocker -D
;@playwright/test
also installed.Add to a .spec
file, inside a beforeEach
or test
method, the hook call useNetworkRecordMocks
passing the test context page, identifier of the mock (only necessary if each test scenario has a different mock), and a route to be used by the recording tab if there is no mock file yet;
import { useNetworkRecordMocks } from 'playwright-request-mocker'; // if using .mjs / .ts
// const { useNetworkRecordMocks } = require('playwright-request-mocker'); //if using .js
test.describe('Your test', () => {
// If your network requests/responses are the same for every test scenario, define it here.
test.beforeEach(async ({ page }) => {
await useNetworkRecordMocks(page, {
recordRoute: ${process.env.APP_URL}/page-you-are-testing
,
});
await page.goto(`${process.env.APP_URL}/page-you-are-testing`);
});
// else use it here if each test scenario expects different results.
test('scenario1', async ({ page }) => {
// It'll generate a new file if it does not exist (".spec.scenario1.mocks.json")
// then it'll read it and mock all defined network requests.
await useNetworkRecordMocks(page, {
identifier: 'scenario1',
recordRoute: ${process.env.APP_URL}/page-you-are-testing
});
await page.goto(`${process.env.APP_URL}/page-you-are-testing`);
//... your steps and asserts.
}); });
1. Run in debug mode;
- PWDEBUG=console forces Playwright to run headed, disables the timeouts and shows the console helper.
// Linux/macOS PWDEBUG=console npm run playwright test
// Windows on cmd.exe set PWDEBUG=console npm run playwright test
// Windows on PowerShell $env:PWDEBUG="console" npm run playwright test
- If the mock file does not exist yet, it'll open a new tab and will be recording all the XHR requests as you navigate. When you think you recorded everything you needed, press the resume button in the ``playwright/test`` UI.
- After it, or if the mock file ever exists, it will use the results to run your test scenario.
### How it works :question:
- useNetworkRecordMocks checks if there is a file ``[invoker-file-name].mocks.json`` (or ``[invoker-file-name].[identifier].mocks.json``), if it doesn't exists, it'll open a chromiun tab using chrome's [recordHAR](https://en.wikipedia.org/wiki/HAR_(file_format)) option. When the Playwright debug mode is unpaused, it'll process such file removing every request other than XHR ones;
- useNetworkRecordMocks will parse the existing file, and mock every request declared on it.
### Different use cases :footprints:
- **For a given test scenario, I need to change the mocked value**: there are 3 ways to achieve this, 1 being creating a new specific mock file at each scenario (by calling useNetworkRecordMocks inside each test with a identifier), and others being overriding the route response, like the following:
Overriding approach: for when the ``useNetworkRecordMocks`` call is inside the test scenario:
``` ts
import { useNetworkRecordMocks, mockRouteResponse } from 'playwright-request-mocker';
// [...]
test('my different scenario', async ({
page,
}) => {
const errorMessage = 'error message I expect';
await useNetworkRecordMocks(page, {
recordRoute: `${process.env.APP_URL}/page-you-are-testing`,
overrideResponses: {
"/ENDPOINT_TO_CHANGE": { errors: [{ message: errorMessage }] }
}
});
await page.goto(`${process.env.APP_URL}/page-you-are-testing`);
await Promise.all([
page.waitForRequest('**/ENDPOINT_TO_CHANGE'),
fillForm(page),
]);
await page.waitForSelector(`text=${errorMessage}`);
const visible = await page.isVisible(`text=${errorMessage}`);
expect(visible).toBeTruthy();
});
Unrouting approach: for when the useNetworkRecordMocks
call is inside a beforeEach
:
test.describe('Test', () => {
test.beforeEach(async ({ page }) => {
await useNetworkRecordMocks(page, {
recordRoute: `${process.env.APP_URL}/page-you-are-testing`,
});
await page.goto(`${process.env.APP_URL}/page-you-are-testing`);
});
test('my different scenario', async ({
page
}) => {
const errorMessage = 'error message I expect';
page.unroute('**/ENDPOINT_TO_CHANGE');
mockRouteResponse(
page,
'**/ENDPOINT_TO_CHANGE',
{ errors: [{ message: errorMessage }] },
400,
);
await Promise.all([
page.waitForRequest('**/ENDPOINT_TO_CHANGE'),
fillForm(page),
]);
await page.waitForSelector(`text=${errorMessage}`);
const visible = await page.isVisible(`text=${errorMessage}`);
expect(visible).toBeTruthy();
});
}
useNetworkRecordMocks
returns every mocked request payload, you can use it to assert the values: test('my different scenario', async ({
page,
}) => {
const requests = await useNetworkRecordMocks(
page,
{
recordRoute: `${process.env.APP_URL}/test-route`,
}
);
const [req] = await Promise.all([
page.waitForRequest('**/ENDPOINT_TO_TEST'),
fillForm(page),
]);
const expectedPayload = requests.find(r => r.url.includes('ENDPOINT_TO_TEST'))?.requestData;
expect(expectedPayload).toStrictEqual(req.postDataJSON());
});
/tests
|- my-test.spec.js
|- my-test.spec.har
|- my-test.spec.identifier.har
----
Feel free to contribute, report bugs, or [contact me](https://github.com/kousenlsn).