Function withEnv

Package: @litert/utils-testSource: packages/partials/test/src/Functions/WithEnv.ts

Temporarily sets environment variables for the duration of a callback, then restores the original values when the callback completes. This function supports both synchronous and asynchronous callbacks.

When the callback returns a Promise, environment variables are restored after the promise settles (either fulfills or rejects). When the callback is synchronous, environment variables are restored immediately after the callback returns or throws.

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Import

import { withEnv } from '@litert/utils-test';

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Signature

function withEnv<T extends () => any>(
    env: IDict,
    cb: T,
): ReturnType<T>;

Where IDict is from @litert/utils-ts-types:

type IDict<T = any, TKey extends string | number | symbol = string | number | symbol> = Record<TKey, T>;

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Parameters

Parameter	Type	Description
env	IDict	An object whose keys are environment variable names and whose values are the values to set for the duration of the callback
cb	T	The callback function to execute with the specified environment variables set

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Return Value

Returns ReturnType<T> — the exact value that cb returns. If cb is async, a Promise is returned that settles with the same value or rejection as the callback.

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Error Handling

Any error thrown by cb is re-thrown to the caller after the environment variables have been restored to their original values.

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Examples

Synchronous callback

import { withEnv } from '@litert/utils-test';

withEnv({ NODE_ENV: 'test', DEBUG: '1' }, () => {
    console.log(process.env.NODE_ENV); // 'test'
    console.log(process.env.DEBUG);    // '1'
});

// process.env.NODE_ENV and process.env.DEBUG are restored to their previous values here

Asynchronous callback

import { withEnv } from '@litert/utils-test';

const result = await withEnv({ NODE_ENV: 'production' }, async () => {
    await someAsyncOperation();
    return process.env.NODE_ENV;
});

// process.env.NODE_ENV is restored to its previous value here
console.log(result); // 'production'