Move tests to __tests__ folders, add unit tests for shared utils and services

Restructure tests into __tests__/ directories at package root so they can
be excluded from production builds. Add unit tests for dates, currency,
lookup service, payment method default logic, and tax exemption state
transitions.

packages/backend/__tests__/routes/v1/inventory.test.ts

@@ -0,0 +1,193 @@
+import { describe, it, expect, beforeAll, beforeEach, afterAll } from 'bun:test'
+import type { FastifyInstance } from 'fastify'
+import {
+  createTestApp,
+  cleanDb,
+  seedTestCompany,
+  registerAndLogin,
+} from '../../../src/test/helpers.js'
+
+describe('Category routes', () => {
+  let app: FastifyInstance
+  let token: string
+
+  beforeAll(async () => {
+    app = await createTestApp()
+  })
+
+  beforeEach(async () => {
+    await cleanDb(app)
+    await seedTestCompany(app)
+    const auth = await registerAndLogin(app)
+    token = auth.token
+  })
+
+  afterAll(async () => {
+    await app.close()
+  })
+
+  it('creates a category', async () => {
+    const response = await app.inject({
+      method: 'POST',
+      url: '/v1/categories',
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: 'Guitars', description: 'All guitars', sortOrder: 1 },
+    })
+
+    expect(response.statusCode).toBe(201)
+    expect(response.json().name).toBe('Guitars')
+    expect(response.json().sortOrder).toBe(1)
+  })
+
+  it('creates a child category', async () => {
+    const parentRes = await app.inject({
+      method: 'POST',
+      url: '/v1/categories',
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: 'Instruments' },
+    })
+    const parentId = parentRes.json().id
+
+    const childRes = await app.inject({
+      method: 'POST',
+      url: '/v1/categories',
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: 'Brass', parentId },
+    })
+
+    expect(childRes.statusCode).toBe(201)
+    expect(childRes.json().parentId).toBe(parentId)
+  })
+
+  it('lists categories sorted by sortOrder', async () => {
+    await app.inject({
+      method: 'POST',
+      url: '/v1/categories',
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: 'Zzz Last', sortOrder: 99 },
+    })
+    await app.inject({
+      method: 'POST',
+      url: '/v1/categories',
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: 'Aaa First', sortOrder: 1 },
+    })
+
+    const response = await app.inject({
+      method: 'GET',
+      url: '/v1/categories',
+      headers: { authorization: `Bearer ${token}` },
+    })
+
+    expect(response.statusCode).toBe(200)
+    const body = response.json()
+    expect(body.data.length).toBe(2)
+    expect(body.data[0].name).toBe('Aaa First')
+  })
+
+  it('soft-deletes a category', async () => {
+    const createRes = await app.inject({
+      method: 'POST',
+      url: '/v1/categories',
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: 'To Delete' },
+    })
+
+    const delRes = await app.inject({
+      method: 'DELETE',
+      url: `/v1/categories/${createRes.json().id}`,
+      headers: { authorization: `Bearer ${token}` },
+    })
+    expect(delRes.json().isActive).toBe(false)
+
+    const listRes = await app.inject({
+      method: 'GET',
+      url: '/v1/categories',
+      headers: { authorization: `Bearer ${token}` },
+    })
+    expect(listRes.json().data.length).toBe(0)
+  })
+})
+
+describe('Supplier routes', () => {
+  let app: FastifyInstance
+  let token: string
+
+  beforeAll(async () => {
+    app = await createTestApp()
+  })
+
+  beforeEach(async () => {
+    await cleanDb(app)
+    await seedTestCompany(app)
+    const auth = await registerAndLogin(app, { email: `supplier-${Date.now()}@test.com` })
+    token = auth.token
+  })
+
+  afterAll(async () => {
+    await app.close()
+  })
+
+  it('creates a supplier', async () => {
+    const response = await app.inject({
+      method: 'POST',
+      url: '/v1/suppliers',
+      headers: { authorization: `Bearer ${token}` },
+      payload: {
+        name: 'RS Musical',
+        contactName: 'Bob Smith',
+        email: 'bob@rsmusical.com',
+        paymentTerms: 'Net 30',
+      },
+    })
+
+    expect(response.statusCode).toBe(201)
+    expect(response.json().name).toBe('RS Musical')
+    expect(response.json().paymentTerms).toBe('Net 30')
+  })
+
+  it('searches suppliers by name', async () => {
+    await app.inject({
+      method: 'POST',
+      url: '/v1/suppliers',
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: "Ferree's Tools" },
+    })
+    await app.inject({
+      method: 'POST',
+      url: '/v1/suppliers',
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: 'Allied Supply' },
+    })
+
+    const response = await app.inject({
+      method: 'GET',
+      url: '/v1/suppliers?q=ferree',
+      headers: { authorization: `Bearer ${token}` },
+    })
+
+    expect(response.statusCode).toBe(200)
+    expect(response.json().data.length).toBe(1)
+    expect(response.json().data[0].name).toBe("Ferree's Tools")
+  })
+
+  it('updates a supplier', async () => {
+    const createRes = await app.inject({
+      method: 'POST',
+      url: '/v1/suppliers',
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: 'Old Name' },
+    })
+
+    const updateRes = await app.inject({
+      method: 'PATCH',
+      url: `/v1/suppliers/${createRes.json().id}`,
+      headers: { authorization: `Bearer ${token}` },
+      payload: { name: 'New Name', paymentTerms: 'COD' },
+    })
+
+    expect(updateRes.statusCode).toBe(200)
+    expect(updateRes.json().name).toBe('New Name')
+    expect(updateRes.json().paymentTerms).toBe('COD')
+  })
+})