Implement basic tests for webui

webui/src/lib/__tests__/api.test.ts

@@ -0,0 +1,60 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { instancesApi } from '@/lib/api'
+
+// Mock fetch globally
+const mockFetch = vi.fn()
+global.fetch = mockFetch
+
+describe('API Error Handling', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  it('converts HTTP errors to meaningful messages', async () => {
+    mockFetch.mockResolvedValue({
+      ok: false,
+      status: 409,
+      text: () => Promise.resolve('Instance already exists')
+    })
+
+    await expect(instancesApi.create('existing', {}))
+      .rejects
+      .toThrow('HTTP 409: Instance already exists')
+  })
+
+  it('handles empty error responses gracefully', async () => {
+    mockFetch.mockResolvedValue({
+      ok: false,
+      status: 500,
+      text: () => Promise.resolve('')
+    })
+
+    await expect(instancesApi.list())
+      .rejects
+      .toThrow('HTTP 500')
+  })
+
+  it('handles 204 No Content responses', async () => {
+    mockFetch.mockResolvedValue({
+      ok: true,
+      status: 204
+    })
+
+    const result = await instancesApi.delete('test-instance')
+    expect(result).toBeUndefined()
+  })
+
+  it('builds query parameters correctly for logs', async () => {
+    mockFetch.mockResolvedValue({
+      ok: true,
+      text: () => Promise.resolve('logs')
+    })
+
+    await instancesApi.getLogs('test-instance', 100)
+
+    expect(mockFetch).toHaveBeenCalledWith(
+      '/api/v1/instances/test-instance/logs?lines=100',
+      expect.any(Object)
+    )
+  })
+})