fix: init uses yarn assuming version > 1.x

Checks that we're using yarn > 1.x when calling `yarn set` which isn't
supported [1] but is for later versions [2]. Update tests to support
environment change differences between yarn 1.x & 3.x.

[1] https://classic.yarnpkg.com/en/docs/cli/set
[2] https://yarnpkg.com/cli/set/version

__e2e__/init.test.ts

@@ -1,11 +1,25 @@
 import fs from 'fs';
 import path from 'path';
 import {runCLI, getTempDirectory, cleanup, writeFiles} from '../jest/helpers';
+import {execSync} from 'child_process';
+import semver from 'semver';
 import slash from 'slash';
 
 const DIR = getTempDirectory('command-init');
 const PROJECT_NAME = 'TestInit';
 
+const yarnVersion = semver.parse(
+  execSync('yarn --version').toString().trim()
+)!;
+
+const yarnConfigFiles: string[] = [];
+if (yarnVersion.major >= 3) {
+  yarnConfigFiles.push(
+    '.yarnrc.yml',
+    '.yarn',
+  );
+}
+
 function createCustomTemplateFiles() {
   writeFiles(DIR, {
     'custom/template/template.config.js': `module.exports = {
@@ -22,8 +36,7 @@ function createCustomTemplateFiles() {
 
 const customTemplateCopiedFiles = [
   '.git',
-  '.yarn',
-  '.yarnrc.yml',
+  ...yarnConfigFiles,
   'dir',
   'file',
   'node_modules',
@@ -178,7 +191,7 @@ test('init uses npm as the package manager with --npm', () => {
   // Remove yarn specific files and node_modules
   const filteredFiles = customTemplateCopiedFiles.filter(
     (file) =>
-      !['yarn.lock', 'node_modules', '.yarnrc.yml', '.yarn'].includes(file),
+      !['yarn.lock', 'node_modules', ...yarnConfigFiles].includes(file),
   );
 
   // Add package-lock.json

packages/cli/src/commands/init/init.ts

@@ -83,7 +83,8 @@ const bumpYarnVersion = async (silent: boolean, root: string) => {
   try {
     let yarnVersion = semver.parse(getYarnVersionIfAvailable());
 
-    if (yarnVersion) {
+    // `yarn set` is unsupported in 1.x
+    if (yarnVersion && yarnVersion.major > 1) {
       await executeCommand('yarn', ['set', 'version', YARN_VERSION], {
         root,
         silent,