test: isolate e2e test npm+yarn cache directories

Author: jbedard

tests/legacy-cli/e2e/setup/002-npm-sandbox.ts

@@ -12,6 +12,8 @@ export default async function () {
   const npmRegistry: string = getGlobalVariable('package-registry');
   const npmrc = join(tempRoot, '.npmrc');
   const yarnrc = join(tempRoot, '.yarnrc');
+  const npmCacheFolder = join(tempRoot, 'npm-cache-folder');
+  const yarnCacheFolder = join(tempRoot, 'yarn-cache-folder');
 
   // Change the npm+yarn userconfig to the sandboxed npmrc to override the default ~
   process.env.NPM_CONFIG_USERCONFIG = npmrc;
@@ -24,6 +26,10 @@ export default async function () {
   process.env.NPM_CONFIG_PREFIX = npmModulesPrefix;
   process.env.YARN_CONFIG_PREFIX = yarnModulesPrefix;
 
+  // Package cache diretories
+  process.env.NPM_CONFIG_CACHE = npmCacheFolder;
+  process.env.YARN_CACHE_FOLDER = yarnCacheFolder;
+
   // Snapshot builds may contain versions that are not yet released (e.g., RC phase main branch).
   // In this case peer dependency ranges may not resolve causing npm 7+ to fail during tests.
   // To support this case, legacy peer dependency mode is enabled for snapshot builds.
@@ -32,11 +38,19 @@ export default async function () {
   }
 
   // Configure the registry and prefix used within the test sandbox via rc files
-  await writeFile(npmrc, `registry=${npmRegistry}\nprefix=${npmModulesPrefix}`);
-  await writeFile(yarnrc, `registry ${npmRegistry}\nprefix ${yarnModulesPrefix}`);
+  await writeFile(
+    npmrc,
+    `registry=${npmRegistry}\nprefix=${npmModulesPrefix}\ncache=${npmCacheFolder}`,
+  );
+  await writeFile(
+    yarnrc,
+    `registry ${npmRegistry}\nprefix ${yarnModulesPrefix}\ncache-folder ${yarnCacheFolder}`,
+  );
 
   await mkdir(npmModulesPrefix);
   await mkdir(yarnModulesPrefix);
+  await mkdir(npmCacheFolder);
+  await mkdir(yarnCacheFolder);
 
   setGlobalVariable('npm-global', npmModulesPrefix);
   setGlobalVariable('yarn-global', yarnModulesPrefix);