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# Disallow using `expect` outside of `it` or `test` blocks (`no-standalone-expect`)
Prevents `expect` statements outside of a `test` or `it` block. An `expect`
within a helper function (but outside of a `test` or `it` block) will not
trigger this rule.
## Rule Details
This rule aims to eliminate `expect` statements that will not be executed. An
`expect` inside of a `describe` block but outside of a `test` or `it` block or
outside a `describe` will not execute and therefore will trigger this rule. It
is viable, however, to have an `expect` in a helper function that is called from
within a `test` or `it` block so `expect` statements in a function will not
trigger this rule.
Statements like `expect.hasAssertions()` will NOT trigger this rule since these
calls will execute if they are not in a test block.
Examples of **incorrect** code for this rule:
```js
// in describe
describe('a test', () => {
expect(1).toBe(1);
});
// below other tests
describe('a test', () => {
it('an it', () => {
expect(1).toBe(1);
});
expect(1).toBe(1);
});
```
Examples of **correct** code for this rule:
```js
// in it block
describe('a test', () => {
it('an it', () => {
expect(1).toBe(1);
});
});
// in helper function
describe('a test', () => {
const helper = () => {
expect(1).toBe(1);
};
it('an it', () => {
helper();
});
});
describe('a test', () => {
expect.hasAssertions(1);
});
```
\*Note that this rule will not trigger if the helper function is never used even
thought the `expect` will not execute. Rely on a rule like no-unused-vars for
this case.
### Options
#### `additionalTestBlockFunctions`
This array can be used to specify the names of functions that should also be
treated as test blocks:
```json
{
"rules": {
"jest/no-standalone-expect": [
"error",
{ "additionalTestBlockFunctions": ["each.test"] }
]
}
}
```
The following is _correct_ when using the above configuration:
```js
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).test('returns the result of adding %d to %d', (a, b, expected) => {
expect(a + b).toBe(expected);
});
```
## When Not To Use It
Don't use this rule on non-jest test files.