github-pages-deploy-action/node_modules/eslint-plugin-jest/docs/rules/prefer-to-be-undefined.md
2020-03-06 22:45:40 -05:00

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# Suggest using `toBeUndefined()` (prefer-to-be-undefined)
In order to have a better failure message, `toBeUndefined()` should be used upon
asserting expections on undefined value.
## Rule details
This rule triggers a warning if `toBe()`, `toEqual()` or `toStrictEqual()` is
used to assert an undefined value.
```js
expect(undefined).toBe(undefined);
```
This rule is enabled by default.
### Default configuration
The following patterns are considered warnings:
```js
expect(undefined).toBe(undefined);
expect(undefined).toEqual(undefined);
expect(undefined).toStrictEqual(undefined);
```
The following pattern is not warning:
```js
expect(undefined).toBeUndefined();
```