190 lines
4.6 KiB
Markdown
190 lines
4.6 KiB
Markdown
# Require setup and teardown code to be within a hook (`require-hook`)
|
|
|
|
<!-- end auto-generated rule header -->
|
|
|
|
Often while writing tests you have some setup work that needs to happen before
|
|
tests run, and you have some finishing work that needs to happen after tests
|
|
run. Jest provides helper functions to handle this.
|
|
|
|
It's common when writing tests to need to perform setup work that needs to
|
|
happen before tests run, and finishing work after tests run.
|
|
|
|
Because Jest executes all `describe` handlers in a test file _before_ it
|
|
executes any of the actual tests, it's important to ensure setup and teardown
|
|
work is done inside `before*` and `after*` handlers respectively, rather than
|
|
inside the `describe` blocks.
|
|
|
|
## Rule details
|
|
|
|
This rule flags any expression that is either at the toplevel of a test file or
|
|
directly within the body of a `describe`, _except_ for the following:
|
|
|
|
- `import` statements
|
|
- `const` variables
|
|
- `let` _declarations_, and initializations to `null` or `undefined`
|
|
- Classes
|
|
- Types
|
|
- Calls to the standard Jest globals
|
|
|
|
This rule flags any function calls within test files that are directly within
|
|
the body of a `describe`, and suggests wrapping them in one of the four
|
|
lifecycle hooks.
|
|
|
|
Here is a slightly contrived test file showcasing some common cases that would
|
|
be flagged:
|
|
|
|
```js
|
|
import { database, isCity } from '../database';
|
|
import { Logger } from '../../../src/Logger';
|
|
import { loadCities } from '../api';
|
|
|
|
jest.mock('../api');
|
|
|
|
const initializeCityDatabase = () => {
|
|
database.addCity('Vienna');
|
|
database.addCity('San Juan');
|
|
database.addCity('Wellington');
|
|
};
|
|
|
|
const clearCityDatabase = () => {
|
|
database.clear();
|
|
};
|
|
|
|
initializeCityDatabase();
|
|
|
|
test('that persists cities', () => {
|
|
expect(database.cities.length).toHaveLength(3);
|
|
});
|
|
|
|
test('city database has Vienna', () => {
|
|
expect(isCity('Vienna')).toBeTruthy();
|
|
});
|
|
|
|
test('city database has San Juan', () => {
|
|
expect(isCity('San Juan')).toBeTruthy();
|
|
});
|
|
|
|
describe('when loading cities from the api', () => {
|
|
let consoleWarnSpy = jest.spyOn(console, 'warn');
|
|
|
|
loadCities.mockResolvedValue(['Wellington', 'London']);
|
|
|
|
it('does not duplicate cities', async () => {
|
|
await database.loadCities();
|
|
|
|
expect(database.cities).toHaveLength(4);
|
|
});
|
|
|
|
it('logs any duplicates', async () => {
|
|
await database.loadCities();
|
|
|
|
expect(consoleWarnSpy).toHaveBeenCalledWith(
|
|
'Ignored duplicate cities: Wellington',
|
|
);
|
|
});
|
|
});
|
|
|
|
clearCityDatabase();
|
|
```
|
|
|
|
Here is the same slightly contrived test file showcasing the same common cases
|
|
but in ways that would be **not** flagged:
|
|
|
|
```js
|
|
import { database, isCity } from '../database';
|
|
import { Logger } from '../../../src/Logger';
|
|
import { loadCities } from '../api';
|
|
|
|
jest.mock('../api');
|
|
|
|
const initializeCityDatabase = () => {
|
|
database.addCity('Vienna');
|
|
database.addCity('San Juan');
|
|
database.addCity('Wellington');
|
|
};
|
|
|
|
const clearCityDatabase = () => {
|
|
database.clear();
|
|
};
|
|
|
|
beforeEach(() => {
|
|
initializeCityDatabase();
|
|
});
|
|
|
|
test('that persists cities', () => {
|
|
expect(database.cities.length).toHaveLength(3);
|
|
});
|
|
|
|
test('city database has Vienna', () => {
|
|
expect(isCity('Vienna')).toBeTruthy();
|
|
});
|
|
|
|
test('city database has San Juan', () => {
|
|
expect(isCity('San Juan')).toBeTruthy();
|
|
});
|
|
|
|
describe('when loading cities from the api', () => {
|
|
let consoleWarnSpy;
|
|
|
|
beforeEach(() => {
|
|
consoleWarnSpy = jest.spyOn(console, 'warn');
|
|
loadCities.mockResolvedValue(['Wellington', 'London']);
|
|
});
|
|
|
|
it('does not duplicate cities', async () => {
|
|
await database.loadCities();
|
|
|
|
expect(database.cities).toHaveLength(4);
|
|
});
|
|
|
|
it('logs any duplicates', async () => {
|
|
await database.loadCities();
|
|
|
|
expect(consoleWarnSpy).toHaveBeenCalledWith(
|
|
'Ignored duplicate cities: Wellington',
|
|
);
|
|
});
|
|
});
|
|
|
|
afterEach(() => {
|
|
clearCityDatabase();
|
|
});
|
|
```
|
|
|
|
## Options
|
|
|
|
If there are methods that you want to call outside of hooks and tests, you can
|
|
mark them as allowed using the `allowedFunctionCalls` option.
|
|
|
|
```json
|
|
{
|
|
"jest/require-hook": [
|
|
"error",
|
|
{
|
|
"allowedFunctionCalls": ["enableAutoDestroy"]
|
|
}
|
|
]
|
|
}
|
|
```
|
|
|
|
Examples of **correct** code when using
|
|
`{ "allowedFunctionCalls": ["enableAutoDestroy"] }` option:
|
|
|
|
```js
|
|
/* eslint jest/require-hook: ["error", { "allowedFunctionCalls": ["enableAutoDestroy"] }] */
|
|
|
|
import { enableAutoDestroy, mount } from '@vue/test-utils';
|
|
import { initDatabase, tearDownDatabase } from './databaseUtils';
|
|
|
|
enableAutoDestroy(afterEach);
|
|
|
|
beforeEach(initDatabase);
|
|
afterEach(tearDownDatabase);
|
|
|
|
describe('Foo', () => {
|
|
test('always returns 42', () => {
|
|
expect(global.getAnswer()).toBe(42);
|
|
});
|
|
});
|
|
```
|