WIP

step1/tests/store.test.js

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+import { getAll, getById, create, updateById, deleteById } from '../store.js'
+import { writeFileSync } from 'node:fs'
+import { join } from 'node:path'
+
+const dbPath = join(process.cwd(), 'db.json')
+const restoreDb = () => writeFileSync(dbPath, JSON.stringify([]))
+const populateDb = (data) => writeFileSync(dbPath, JSON.stringify(data))
+const fixtures = [{ id: 1, message: 'test' }, { id: 2, message: 'hello world' }]
+const inventedId = 12345
+const existingId = fixtures[0].id
+
+describe('store', () => {
+  beforeEach(() => populateDb(fixtures))
+  afterAll(restoreDb)
+  describe('getAll', () => {
+    it("Should return an empty array when there's no data", async () => {
+      restoreDb()
+      const data = await getAll()
+      expect(data).toEqual([])
+    })
+    it('Should return an array with one item when there is one item', async () => {
+      const data = await getAll()
+      expect(data).toEqual(fixtures)
+    })
+  })
+  describe('getById', () => {
+    it('Should return undefined when there is no item with the given id', async () => {
+      const item = await getById(inventedId)
+      expect(item).toBeUndefined()
+    })
+    it('Should return the item with the given id', async () => {
+      const item = await getById(fixtures[0].id)
+      expect(item).toEqual(fixtures[0])
+    })
+  })
+  describe('create', () => {
+    it('Should return the created item', async () => {
+      const newItem = { id: fixtures.length + 1, message: 'test 3' }
+      const item = await create(newItem.message)
+      expect(item).toEqual(newItem)
+    })
+    it('Should add the item to the db', async () => {
+      const newItem = { id: fixtures.length + 1, message: 'test 3' }
+      const { id } = await create(newItem.message)
+      const item = await getById(id)
+      expect(item).toEqual(newItem)
+    })
+  })
+  describe('updateById', () => {
+    it('Should return undefined when there is no item with the given id', async () => {
+      const item = await updateById(inventedId)
+      expect(item).toBeUndefined()
+    })
+    it('Should not return the updated item', async () => {
+      const updatedItem = { id: existingId, message: 'updated' }
+      const item = await updateById(updatedItem.id, updatedItem.message)
+      expect(item).toBeUndefined()
+    })
+    it('Should update the item in the db', async () => {
+      const updatedItem = { id: existingId, message: 'updated' }
+      await updateById(updatedItem.id, updatedItem.message)
+      const item = await getById(existingId)
+      expect(item).toEqual(updatedItem)
+    })
+  })
+  describe('deleteById', () => {
+    it('Should return undefined when there is no item with the given id', async () => {
+      const item = await deleteById(inventedId)
+      expect(item).toBeUndefined()
+    })
+    it('Should not return the deleted item', async () => {
+      const item = await deleteById(existingId)
+      expect(item).toBeUndefined()
+    })
+    it('Should delete the item from the db', async () => {
+      await deleteById(existingId)
+      const items = await getAll()
+      expect(items).toEqual(fixtures.filter(item => item.id !== existingId))
+    })
+  })
+})