define env type (#1141)

Co-authored-by: ehmicky <ehmicky@users.noreply.github.com>

test-d/arguments/env.test-d.ts

@@ -0,0 +1,31 @@
+import process, {type env} from 'node:process';
+import {expectType, expectAssignable} from 'tsd';
+import {execa, type Options, type Result} from '../../index.js';
+
+type NodeEnv = 'production' | 'development' | 'test';
+
+// Libraries like Next.js or Remix do the following type augmentation.
+// The following type tests ensure this works with Execa.
+// See https://github.com/sindresorhus/execa/pull/1141 and https://github.com/sindresorhus/execa/issues/1132
+declare global {
+	// eslint-disable-next-line @typescript-eslint/no-namespace
+	namespace NodeJS {
+		// eslint-disable-next-line @typescript-eslint/consistent-type-definitions
+		interface ProcessEnv {
+			readonly NODE_ENV: NodeEnv;
+		}
+	}
+}
+
+// The global types are impacted
+expectType<NodeEnv>(process.env.NODE_ENV);
+expectType<NodeEnv>('' as (typeof env)['NODE_ENV']);
+expectType<NodeEnv>('' as NodeJS.ProcessEnv['NODE_ENV']);
+expectType<NodeEnv>('' as globalThis.NodeJS.ProcessEnv['NODE_ENV']);
+
+// But Execa's types are not impacted
+expectType<string | undefined>('' as Exclude<Options['env'], undefined>['NODE_ENV']);
+expectAssignable<Result>(await execa({env: {test: 'example'}})`unicorns`);
+expectAssignable<Result>(await execa({env: {test: 'example'} as const})`unicorns`);
+expectAssignable<Result>(await execa({env: {test: undefined}})`unicorns`);
+expectAssignable<Result>(await execa({env: {test: undefined} as const})`unicorns`);

types/arguments/options.d.ts

@@ -1,5 +1,4 @@
 import type {SignalConstants} from 'node:os';
-import type {env} from 'node:process';
 import type {Readable} from 'node:stream';
 import type {Unless} from '../utils.js';
 import type {Message} from '../ipc.js';
@@ -77,7 +76,7 @@ export type CommonOptions<IsSync extends boolean = boolean> = {
 
 	@default [process.env](https://nodejs.org/api/process.html#processenv)
 	*/
-	readonly env?: typeof env;
+	readonly env?: Readonly<Partial<Record<string, string>>>;
 
 	/**
 	If `true`, the subprocess uses both the `env` option and the current process' environment variables ([`process.env`](https://nodejs.org/api/process.html#processenv)).