47 lines
1.5 KiB
Markdown
47 lines
1.5 KiB
Markdown
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# jest-create-cache-key-function
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This module creates a function which is used for generating cache keys used by code transformers in Jest.
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## Install
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```sh
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$ npm install --save-dev @jest/create-cache-key-function
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```
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## API
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### `createCacheKey(files?: Array<string>, values?: Array<String>, length?: number): GetCacheKeyFunction`
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Returns a function that can be used to generate cache keys based on source code of provided files and provided values.
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#### Parameters
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- `files`: [Optional] Array of absolute paths to files whose code should be accounted for when generating cache key
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- `values`: [Optional] Array of string values that should be accounted for when generating cache key
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- `length`: [Optional] Length of the resulting key. The default is `32`, or `16` on Windows.
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**Note:**
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The source code for your test is already taken into account when generating the cache key. The `files` array should be used to provide files that are not directly related to your code such as external configuration files.
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## Usage
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Here is some sample usage code while creating a new transformer for Jest
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```javascript
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const createCacheKeyFunction =
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require('@jest/create-cache-key-function').default;
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const filesToAccountFor = [
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__filename,
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require.resolve('some-package-name/package.json'),
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];
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const valuesToAccountFor = [process.env.SOME_LOCAL_ENV, 'Some_Other_Value'];
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module.exports = {
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process(src, filename, config, options) {},
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getCacheKey: createCacheKeyFunction(filesToAccountFor, valuesToAccountFor),
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};
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```
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