Make test async & more generic

Author: AlphaHydrae

tests/exec.js

@@ -1,3 +1,9 @@
 const { execvp } = require('../exec.js');
 
-execvp('ls', ['tests']);
+if (process.argv.length < 3) {
+  throw new Error('Missing command');
+}
+
+const [_node, _file, command, ...args] = process.argv;
+
+execvp(command, args);

tests/exec.spec.js

@@ -1,7 +1,13 @@
-const { execSync } = require('node:child_process');
+const { exec } = require('node:child_process');
+const { promisify } = require('node:util');
+
+const execAsync = promisify(exec);
 
 describe('exec', () => {
-  test('it should work', () => {
-    expect(execSync('node tests/exec.js').toString()).toBe('exec.js\nexec.spec.js\n');
+  test('it should work', async () => {
+    await expect(execAsync('node tests/exec.js ls tests')).resolves.toEqual({
+      stderr: '',
+      stdout: 'exec.js\nexec.spec.js\n'
+    });
   });
 });