add e2e test for CommonJS/ESM

tests/specs/e2e.test.ts

@@ -0,0 +1,72 @@
+import {execUtils}                from '@yarnpkg/core';
+import {xfs, PortablePath, npath} from '@yarnpkg/fslib';
+
+describe(`E2E`, () => {
+  it(`works with CommonJS`, async () => {
+    await xfs.mktempPromise(async tempDir => {
+      const rndName = Math.floor(Math.random() * 100000000).toString(16).padStart(8, `0`);
+
+      const packed = await execUtils.execvp(`yarn`, [`pack`, `--out`, npath.fromPortablePath(`${tempDir}/${rndName}.tgz`)], {
+        cwd: npath.toPortablePath(__dirname),
+      });
+
+      expect(packed.code).toEqual(0);
+
+      await xfs.writeJsonPromise(`${tempDir}/package.json` as PortablePath, {name: `test-treeshake`});
+      await xfs.writeFilePromise(`${tempDir}/yarn.lock` as PortablePath, ``);
+
+      const added = await execUtils.execvp(`yarn`, [`add`, `./${rndName}.tgz`], {cwd: tempDir});
+      expect(added.code).toEqual(0);
+
+      await xfs.writeFilePromise(`${tempDir}/index.cjs` as PortablePath,
+`const {Command, Option, runExit} = require('clipanion');
+ 
+runExit(class MainCommand extends Command {
+  name = Option.String();
+ 
+  async execute() {
+    this.context.stdout.write(\`Hello \${this.name}!\\n\`);
+  }
+})`,
+      );
+
+      const result = await execUtils.execvp(`node`, [`${tempDir}/index.cjs`, 'World'], {cwd: tempDir});
+      expect(result.code).toEqual(0);
+      expect(result.stdout).toEqual('Hello World!\n');
+    });
+  }, 20000);
+
+  it(`works with ESM`, async () => {
+    await xfs.mktempPromise(async tempDir => {
+      const rndName = Math.floor(Math.random() * 100000000).toString(16).padStart(8, `0`);
+
+      const packed = await execUtils.execvp(`yarn`, [`pack`, `--out`, npath.fromPortablePath(`${tempDir}/${rndName}.tgz`)], {
+        cwd: npath.toPortablePath(__dirname),
+      });
+
+      expect(packed.code).toEqual(0);
+
+      await xfs.writeJsonPromise(`${tempDir}/package.json` as PortablePath, {name: `test-treeshake`});
+      await xfs.writeFilePromise(`${tempDir}/yarn.lock` as PortablePath, ``);
+
+      const added = await execUtils.execvp(`yarn`, [`add`, `./${rndName}.tgz`], {cwd: tempDir});
+      expect(added.code).toEqual(0);
+
+      await xfs.writeFilePromise(`${tempDir}/index.mjs` as PortablePath,
+`import {Command, Option, runExit} from 'clipanion';
+ 
+runExit(class MainCommand extends Command {
+  name = Option.String();
+ 
+  async execute() {
+    this.context.stdout.write(\`Hello \${this.name}!\\n\`);
+  }
+})`,
+      );
+
+      const result = await execUtils.execvp(`node`, [`${tempDir}/index.mjs`, 'World'], {cwd: tempDir});
+      expect(result.code).toEqual(0);
+      expect(result.stdout).toEqual('Hello World!\n');
+    });
+  }, 20000);
+});