151 lines
3.7 KiB
Markdown
151 lines
3.7 KiB
Markdown
# Enforce assertion to be made in a test body (`expect-expect`)
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⚠️ This rule _warns_ in the ✅ `recommended`
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[config](https://github.com/jest-community/eslint-plugin-jest/blob/main/README.md#shareable-configurations).
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<!-- end auto-generated rule header -->
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Ensure that there is at least one `expect` call made in a test.
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## Rule details
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This rule triggers when there is no call made to `expect` in a test, to prevent
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users from forgetting to add assertions.
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Examples of **incorrect** code for this rule:
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```js
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it('should be a test', () => {
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console.log('no assertion');
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});
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test('should assert something', () => {});
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```
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Examples of **correct** code for this rule:
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```js
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it('should be a test', () => {
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expect(true).toBeDefined();
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});
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it('should work with callbacks/async', () => {
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somePromise().then(res => expect(res).toBe('passed'));
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});
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```
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## Options
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```json
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{
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"jest/expect-expect": [
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"error",
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{
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"assertFunctionNames": ["expect"],
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"additionalTestBlockFunctions": []
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}
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]
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}
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```
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### `assertFunctionNames`
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This array option specifies the names of functions that should be considered to
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be asserting functions. Function names can use wildcards i.e `request.*.expect`,
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`request.**.expect`, `request.*.expect*`
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Examples of **incorrect** code for the `{ "assertFunctionNames": ["expect"] }`
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option:
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```js
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/* eslint jest/expect-expect: ["error", { "assertFunctionNames": ["expect"] }] */
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import { expectSaga } from 'redux-saga-test-plan';
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import { addSaga } from '../src/sagas';
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test('returns sum', () => {
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expectSaga(addSaga, 1, 1).returns(2).run();
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});
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```
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Examples of **correct** code for the
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`{ "assertFunctionNames": ["expect", "expectSaga"] }` option:
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```js
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/* eslint jest/expect-expect: ["error", { "assertFunctionNames": ["expect", "expectSaga"] }] */
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import { expectSaga } from 'redux-saga-test-plan';
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import { addSaga } from '../src/sagas';
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test('returns sum', () => {
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expectSaga(addSaga, 1, 1).returns(2).run();
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});
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```
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Since the string is compiled into a regular expression, you'll need to escape
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special characters such as `$` with a double backslash:
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```js
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/* eslint jest/expect-expect: ["error", { "assertFunctionNames": ["expect\\$"] }] */
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it('is money-like', () => {
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expect$(1.0);
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});
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```
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Examples of **correct** code for working with the HTTP assertions library
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[SuperTest](https://www.npmjs.com/package/supertest) with the
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`{ "assertFunctionNames": ["expect", "request.**.expect"] }` option:
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```js
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/* eslint jest/expect-expect: ["error", { "assertFunctionNames": ["expect", "request.**.expect"] }] */
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const request = require('supertest');
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const express = require('express');
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const app = express();
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describe('GET /user', function () {
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it('responds with json', function (done) {
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request(app).get('/user').expect('Content-Type', /json/).expect(200, done);
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});
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});
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```
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### `additionalTestBlockFunctions`
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This array can be used to specify the names of functions that should also be
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treated as test blocks:
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```json
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{
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"rules": {
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"jest/expect-expect": [
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"error",
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{ "additionalTestBlockFunctions": ["theoretically"] }
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]
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}
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}
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```
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The following is _correct_ when using the above configuration:
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```js
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import theoretically from 'jest-theories';
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describe('NumberToLongString', () => {
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const theories = [
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{ input: 100, expected: 'One hundred' },
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{ input: 1000, expected: 'One thousand' },
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{ input: 10000, expected: 'Ten thousand' },
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{ input: 100000, expected: 'One hundred thousand' },
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];
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theoretically(
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'the number {input} is correctly translated to string',
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theories,
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theory => {
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const output = NumberToLongString(theory.input);
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expect(output).toBe(theory.expected);
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},
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);
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});
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```
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