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# jest-validate
Generic configuration validation tool that helps you with warnings, errors and deprecation messages as well as showing users examples of correct configuration.
```bash
npm install --save jest-validate
```
## Usage
```js
import {validate} from 'jest-validate';
validate(config, validationOptions); // => {hasDeprecationWarnings: boolean, isValid: boolean}
```
Where `ValidationOptions` are:
```ts
type ValidationOptions = {
comment?: string;
condition?: (option: unknown, validOption: unknown) => boolean;
deprecate?: (
config: Record<string, unknown>,
option: string,
deprecatedOptions: DeprecatedOptions,
options: ValidationOptions,
) => boolean;
deprecatedConfig?: DeprecatedOptions;
error?: (
option: string,
received: unknown,
defaultValue: unknown,
options: ValidationOptions,
path?: Array<string>,
) => void;
exampleConfig: Record<string, unknown>;
recursive?: boolean;
recursiveBlacklist?: Array<string>;
recursiveDenylist?: Array<string>;
title?: Title;
unknown?: (
config: Record<string, unknown>,
exampleConfig: Record<string, unknown>,
option: string,
options: ValidationOptions,
path?: Array<string>,
) => void;
};
type Title = {
deprecation?: string;
error?: string;
warning?: string;
};
```
`exampleConfig` is the only option required.
## API
By default `jest-validate` will print generic warning and error messages. You can however customize this behavior by providing `options: ValidationOptions` object as a second argument:
Almost anything can be overwritten to suite your needs.
### Options
- `recursiveDenylist` optional array of string keyPaths that should be excluded from deep (recursive) validation.
- `comment` optional string to be rendered below error/warning message.
- `condition` an optional function with validation condition.
- `deprecate`, `error`, `unknown` optional functions responsible for displaying warning and error messages.
- `deprecatedConfig` optional object with deprecated config keys.
- `exampleConfig` the only **required** option with configuration against which you'd like to test.
- `recursive` - optional boolean determining whether recursively compare `exampleConfig` to `config` (default: `true`).
- `title` optional object of titles for errors and messages.
You will find examples of `condition`, `deprecate`, `error`, `unknown`, and `deprecatedConfig` inside source of this repository, named respectively.
## exampleConfig syntax
`exampleConfig` should be an object with key/value pairs that contain an example of a valid value for each key. A configuration value is considered valid when:
- it matches the JavaScript type of the example value, e.g. `string`, `number`, `array`, `boolean`, `function`, or `object`
- it is `null` or `undefined`
- it matches the Javascript type of any of arguments passed to `MultipleValidOptions(...)`
The last condition is a special syntax that allows validating where more than one type is permissible; see example below. It's acceptable to have multiple values of the same type in the example, so you can also use this syntax to provide more than one example. When a validation failure occurs, the error message will show all other values in the array as examples.
## Examples
Minimal example:
```js
validate(config, {exampleConfig});
```
Example with slight modifications:
```js
validate(config, {
comment: ' Documentation: http://custom-docs.com',
deprecatedConfig,
exampleConfig,
title: {
deprecation: 'Custom Deprecation',
// leaving 'error' and 'warning' as default
},
});
```
This will output:
#### Warning:
```bash
● Validation Warning:
Unknown option transformx with value "<rootDir>/node_modules/babel-jest" was found.
This is either a typing error or a user mistake. Fixing it will remove this message.
Documentation: http://custom-docs.com
```
#### Error:
```bash
● Validation Error:
Option transform must be of type:
object
but instead received:
string
Example:
{
"transform": {
"\\.js$": "<rootDir>/preprocessor.js"
}
}
Documentation: http://custom-docs.com
```
## Example validating multiple types
```js
import {multipleValidOptions} from 'jest-validate';
validate(config, {
// `bar` will accept either a string or a number
bar: multipleValidOptions('string is ok', 2),
});
```
#### Error:
```bash
● Validation Error:
Option foo must be of type:
string or number
but instead received:
array
Example:
{
"bar": "string is ok"
}
or
{
"bar": 2
}
Documentation: http://custom-docs.com
```
#### Deprecation
Based on `deprecatedConfig` object with proper deprecation messages. Note custom title:
```bash
Custom Deprecation:
Option scriptPreprocessor was replaced by transform, which support multiple preprocessors.
Jest now treats your current configuration as:
{
"transform": {".*": "xxx"}
}
Please update your configuration.
Documentation: http://custom-docs.com
```