Add smoke tests for CLI

- Introduced `smoke.test.ts` to verify that the CLI tool can run essential commands without errors.
- Includes tests for basic CLI usage and ERD command execution, checking for expected output.

frontend/packages/cli/src/cli/smoke.test.ts

@@ -0,0 +1,55 @@
+import { exec } from 'node:child_process'
+import { promisify } from 'node:util'
+import { beforeAll, describe, expect, it } from 'vitest'
+
+const execAsync = promisify(exec)
+
+beforeAll(async () => {
+  await execAsync('rm -rf ./dist-cli/ ./node_modules/.tmp')
+  await execAsync('pnpm run build:cli')
+})
+
+describe('CLI Smoke Test', () => {
+  it('should run the CLI command without errors', async () => {
+    try {
+      const { stdout, stderr } = await execAsync('npx --no-install . help')
+      expect(stderr).toBe('')
+      expect(stdout).toEqual(
+        `Usage: liam [options] [command]
+
+CLI tool for Liam
+
+Options:
+  -V, --version   output the version number
+  -h, --help      display help for command
+
+Commands:
+  erd             ERD commands
+  help [command]  display help for command
+`,
+      )
+    } catch (error) {
+      // Fail the test if an error occurs
+      expect(error).toBeNull()
+    }
+  })
+
+  it('should run the CLI command without errors', async () => {
+    await execAsync('rm -rf ./dist')
+    try {
+      const { stdout, stderr } = await execAsync(
+        'npx --no-install . erd build --input fixtures/input.sql',
+      )
+      expect(stderr).toBe('')
+      expect(stdout).toContain('building for production')
+      expect(stdout).toContain('✓ built in')
+      const { stdout: lsOutput } = await execAsync('ls ./dist')
+      expect(lsOutput.trim().length).toBeGreaterThan(0)
+    } catch (error) {
+      // Fail the test if an error occurs
+      expect(error).toBeNull()
+    } finally {
+      await execAsync('rm -rf ./dist')
+    }
+  })
+})