Fix npm prefix test failing under nvm

sindresorhus · sindresorhus · commit dd04056b1239 · 2026-02-02T16:06:27.000+07:00
The test did not clear pre-existing `npm_config_prefix` env vars (e.g. set by nvm) before asserting its own value. Fixes #25
diff --git a/index.js b/index.js
@@ -12,9 +12,10 @@ const readRc = filePath => {
 	} catch {}
 };
 
-// TODO: Remove the `.reduce` call.
-// eslint-disable-next-line unicorn/no-array-reduce
-const getEnvNpmPrefix = () => Object.keys(process.env).reduce((prefix, name) => /^npm_config_prefix$/i.test(name) ? process.env[name] : prefix, undefined);
+const getEnvNpmPrefix = () => {
+	const key = Object.keys(process.env).find(name => name.toLowerCase() === 'npm_config_prefix');
+	return key ? process.env[key] : undefined;
+};
 
 const getGlobalNpmrc = () => {
 	if (isWindows && process.env.APPDATA) {
diff --git a/test.js b/test.js
@@ -4,7 +4,8 @@ import path from 'node:path';
 import test from 'ava';
 import {execa} from 'execa';
 
-const importFresh = async moduleName => import(`${moduleName}?${Date.now()}`);
+let importCounter = 0;
+const importFresh = async moduleName => import(`${moduleName}?${++importCounter}`);
 
 const {default: globalDirectory} = await importFresh('./index.js');
 
@@ -62,9 +63,20 @@ test.serial('yarn with PREFIX', async t => {
 });
 
 test.serial('reload package and get npm.prefix with env', async t => {
+	const savedKeys = Object.keys(process.env).filter(name => name.toLowerCase() === 'npm_config_prefix');
+	const savedValues = Object.fromEntries(savedKeys.map(key => [key, process.env[key]]));
+
+	for (const key of savedKeys) {
+		delete process.env[key];
+	}
+
 	// eslint-disable-next-line camelcase
 	process.env.npm_config_PREFIX = '/usr/local/lib';
 	const {default: globalDirectory} = await importFresh('./index.js');
 	t.is(globalDirectory.npm.prefix, '/usr/local/lib');
 	delete process.env.npm_config_PREFIX;
+
+	for (const [key, value] of Object.entries(savedValues)) {
+		process.env[key] = value;
+	}
 });
