diff --git a/src/config/card-repository-factory.test.ts b/src/config/card-repository-factory.test.ts
new file mode 100644
index 0000000..3119d0b
--- /dev/null
+++ b/src/config/card-repository-factory.test.ts
@@ -0,0 +1,32 @@
+// @vitest-environment node
+import { afterEach, describe, expect, it } from 'vitest'
+import { MongoCardRepository } from '../repositories/mongo-card-repository'
+import { MysqlCardRepository } from '../repositories/mysql-card-repository'
+import { getCardRepository } from './card-repository-factory'
+
+describe('getCardRepository', () => {
+  const original = process.env.DB_IMPL
+
+  afterEach(() => {
+    if (original === undefined) {
+      delete process.env.DB_IMPL
+    } else {
+      process.env.DB_IMPL = original
+    }
+  })
+
+  it('instancie MysqlCardRepository par défaut', () => {
+    delete process.env.DB_IMPL
+    expect(getCardRepository()).toBeInstanceOf(MysqlCardRepository)
+  })
+
+  it('instancie MysqlCardRepository si DB_IMPL=mysql', () => {
+    process.env.DB_IMPL = 'mysql'
+    expect(getCardRepository()).toBeInstanceOf(MysqlCardRepository)
+  })
+
+  it('instancie MongoCardRepository si DB_IMPL=mongo', () => {
+    process.env.DB_IMPL = 'mongo'
+    expect(getCardRepository()).toBeInstanceOf(MongoCardRepository)
+  })
+})
\ No newline at end of file
diff --git a/src/repositories/mongo-card-repository.test.ts b/src/repositories/mongo-card-repository.test.ts
new file mode 100644
index 0000000..86f940d
--- /dev/null
+++ b/src/repositories/mongo-card-repository.test.ts
@@ -0,0 +1,132 @@
+// @vitest-environment node
+import { describe, expect, it, vi } from 'vitest'
+import type { Collection } from 'mongodb'
+import { MongoCardRepository } from './mongo-card-repository'
+
+const DOC = {
+  c_id: '10000000-0000-4000-8000-000000000001',
+  question: "Qu'est-ce qu'une closure ?",
+  response: 'Une fonction qui conserve la portée de sa définition.',
+  theme: 'javascript',
+  tags: ['scope'],
+  createdAt: new Date('2026-01-01T08:00:00Z'),
+  updatedAt: new Date('2026-01-02T09:00:00Z'),
+}
+
+function cursorOf(docs: unknown[]) {
+  return { toArray: vi.fn().mockResolvedValue(docs) }
+}
+
+function setup() {
+  const collection = {
+    find: vi.fn(),
+    findOne: vi.fn(),
+    insertOne: vi.fn(),
+    updateOne: vi.fn(),
+    deleteOne: vi.fn(),
+    aggregate: vi.fn(),
+    distinct: vi.fn(),
+  } as unknown as Collection<any>
+  const repo = new MongoCardRepository(collection)
+  return { repo, collection }
+}
+
+describe('MongoCardRepository', () => {
+  it('findAll renvoie toutes les cartes mappées', async () => {
+    const { repo, collection } = setup()
+    collection.find.mockReturnValue(cursorOf([DOC]) as any)
+    const cards = await repo.findAll()
+    expect(cards).toHaveLength(1)
+    expect(cards[0].id).toBe(DOC.c_id)
+    expect(cards[0].tags).toEqual(['scope'])
+  })
+
+  it('findAll renvoie un tableau vide si aucune carte', async () => {
+    const { repo, collection } = setup()
+    collection.find.mockReturnValue(cursorOf([]) as any)
+    await expect(repo.findAll()).resolves.toEqual([])
+  })
+
+  it('findById renvoie la carte ou null', async () => {
+    const { repo, collection } = setup()
+    collection.findOne.mockResolvedValueOnce(DOC)
+    const card = await repo.findById(DOC.c_id)
+    expect(card?.id).toBe(DOC.c_id)
+    expect(collection.findOne).toHaveBeenCalledWith({ c_id: DOC.c_id }, expect.anything())
+    collection.findOne.mockResolvedValueOnce(null)
+    await expect(repo.findById('inconnu')).resolves.toBeNull()
+  })
+
+  it('create insère un document avec c_id et renvoie l entité', async () => {
+    const { repo, collection } = setup()
+    collection.insertOne.mockResolvedValueOnce({ insertedId: '' } as any)
+    const card = await repo.create({
+      question: 'Que retourne typeof null ?',
+      response: 'object',
+      theme: 'javascript',
+    })
+    const [doc] = collection.insertOne.mock.calls[0]
+    expect(doc.c_id).toBe(card.id)
+    expect(doc.tags).toEqual([])
+    expect(card.tags).toEqual([])
+    expect(card.createdAt).toBeInstanceOf(Date)
+  })
+
+  it('update modifie les champs fournis et renvoie la carte', async () => {
+    const { repo, collection } = setup()
+    collection.updateOne.mockResolvedValueOnce({ matchedCount: 1 } as any)
+    collection.findOne.mockResolvedValueOnce({ ...DOC, response: 'Nouvelle' })
+    const card = await repo.update(DOC.c_id, { response: 'Nouvelle' })
+    expect(card?.response).toBe('Nouvelle')
+    const [filter, set] = collection.updateOne.mock.calls[0]
+    expect(filter).toEqual({ c_id: DOC.c_id })
+    expect(set.$set.response).toBe('Nouvelle')
+    expect(set.$set.updatedAt).toBeInstanceOf(Date)
+  })
+
+  it('update renvoie null si aucune carte ne correspond', async () => {
+    const { repo, collection } = setup()
+    collection.updateOne.mockResolvedValueOnce({ matchedCount: 0 } as any)
+    await expect(repo.update('inconnu', { question: 'X' })).resolves.toBeNull()
+  })
+
+  it('delete renvoie true si un document est supprimé', async () => {
+    const { repo, collection } = setup()
+    collection.deleteOne.mockResolvedValueOnce({ deletedCount: 1 } as any)
+    await expect(repo.delete(DOC.c_id)).resolves.toBe(true)
+    expect(collection.deleteOne).toHaveBeenCalledWith({ c_id: DOC.c_id })
+  })
+
+  it('delete renvoie false si aucun document ne correspond', async () => {
+    const { repo, collection } = setup()
+    collection.deleteOne.mockResolvedValueOnce({ deletedCount: 0 } as any)
+    await expect(repo.delete('inconnu')).resolves.toBe(false)
+  })
+
+  it('findRandom renvoie une carte au hasard ou null', async () => {
+    const { repo, collection } = setup()
+    collection.aggregate.mockReturnValueOnce(cursorOf([DOC]) as any)
+    const card = await repo.findRandom()
+    expect(card?.id).toBe(DOC.c_id)
+    expect(collection.aggregate.mock.calls[0][0]).toContainEqual({ $sample: { size: 1 } })
+    collection.aggregate.mockReturnValueOnce(cursorOf([]) as any)
+    await expect(repo.findRandom()).resolves.toBeNull()
+  })
+
+  it('findRandomByTheme filtre par thème', async () => {
+    const { repo, collection } = setup()
+    collection.aggregate.mockReturnValueOnce(cursorOf([DOC]) as any)
+    const card = await repo.findRandomByTheme('javascript')
+    expect(card?.id).toBe(DOC.c_id)
+    const stages = collection.aggregate.mock.calls[0][0]
+    expect(stages[0]).toEqual({ $match: { theme: 'javascript' } })
+    collection.aggregate.mockReturnValueOnce(cursorOf([]) as any)
+    await expect(repo.findRandomByTheme('react')).resolves.toBeNull()
+  })
+
+  it('findThemes renvoie les thèmes distincts triés', async () => {
+    const { repo, collection } = setup()
+    collection.distinct.mockResolvedValueOnce(['react', 'docker'])
+    await expect(repo.findThemes()).resolves.toEqual(['docker', 'react'])
+  })
+})
\ No newline at end of file
diff --git a/src/repositories/mysql-card-repository.test.ts b/src/repositories/mysql-card-repository.test.ts
new file mode 100644
index 0000000..3867999
--- /dev/null
+++ b/src/repositories/mysql-card-repository.test.ts
@@ -0,0 +1,157 @@
+// @vitest-environment node
+import { describe, expect, it, vi } from 'vitest'
+import type { Pool } from 'mysql2/promise'
+import type { Card } from '../domain/card'
+import { MysqlCardRepository } from './mysql-card-repository'
+
+const ROW = {
+  id: '10000000-0000-4000-8000-000000000001',
+  question: "Qu'est-ce qu'une closure ?",
+  response: 'Une fonction qui conserve la portée de sa définition.',
+  theme: 'javascript',
+  tags: '["scope"]',
+  createdAt: new Date('2026-01-01T08:00:00Z'),
+  updatedAt: new Date('2026-01-02T09:00:00Z'),
+}
+
+const EXPECTED_CARD: Card = {
+  id: ROW.id,
+  question: ROW.question,
+  response: ROW.response,
+  theme: ROW.theme,
+  tags: ['scope'],
+  createdAt: ROW.createdAt,
+  updatedAt: ROW.updatedAt,
+}
+
+function setup() {
+  const query = vi.fn()
+  const pool = { query } as unknown as Pool
+  return { repo: new MysqlCardRepository(pool), query }
+}
+
+describe('MysqlCardRepository', () => {
+  it('findAll renvoie toutes les cartes mappées', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([
+      [ROW, { ...ROW, id: '10000000-0000-4000-8000-000000000002', tags: null }],
+    ])
+    const cards = await repo.findAll()
+    expect(cards).toHaveLength(2)
+    expect(cards[0]).toEqual(EXPECTED_CARD)
+    expect(cards[1].tags).toEqual([])
+  })
+
+  it('findAll renvoie un tableau vide si aucune carte', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([[]])
+    await expect(repo.findAll()).resolves.toEqual([])
+  })
+
+  it('findById renvoie la carte correspondante', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([[ROW]])
+    await expect(repo.findById(ROW.id)).resolves.toEqual(EXPECTED_CARD)
+    expect(query.mock.calls[0][1]).toEqual([ROW.id])
+  })
+
+  it('findById renvoie null si la carte est inconnue', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([[]])
+    await expect(repo.findById('inconnu')).resolves.toBeNull()
+  })
+
+  it('create insère une carte et renvoie l entité complète', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([{ affectedRows: 1 }])
+    const card = await repo.create({
+      question: 'Que retourne typeof null ?',
+      response: 'object',
+      theme: 'javascript',
+      tags: ['types'],
+    })
+    expect(card.id).toHaveLength(36)
+    expect(card.tags).toEqual(['types'])
+    expect(card.createdAt).toBeInstanceOf(Date)
+    const [params] = query.mock.calls[0][1] as unknown[]
+    expect(params).toBe(card.id)
+    expect(query.mock.calls[0][0]).toContain('INSERT INTO cards')
+  })
+
+  it('create utilise un tableau de tags vide si non fourni', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([{ affectedRows: 1 }])
+    const card = await repo.create({ question: 'Q ?', response: 'R', theme: 'git' })
+    expect(card.tags).toEqual([])
+    expect(query.mock.calls[0][1]).toContain('[]')
+  })
+
+  it('update modifie les champs fournis et renvoie la carte', async () => {
+    const { repo, query } = setup()
+    const updated = { ...ROW, response: 'Nouvelle réponse' }
+    query.mockResolvedValueOnce([{ affectedRows: 1 }]).mockResolvedValueOnce([[updated]])
+    const card = await repo.update(ROW.id, { response: 'Nouvelle réponse' })
+    expect(card?.response).toBe('Nouvelle réponse')
+    const [updateCall] = query.mock.calls
+    expect(updateCall[0]).toContain('UPDATE cards SET')
+    expect(updateCall[1]).toContain('Nouvelle réponse')
+  })
+
+  it('update sérialise les tags en JSON', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([{ affectedRows: 1 }]).mockResolvedValueOnce([[ROW]])
+    await repo.update(ROW.id, { tags: ['a', 'b'] })
+    expect(query.mock.calls[0][1]).toContain('["a","b"]')
+  })
+
+  it('update sans champs ne lance pas d UPDATE', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([[ROW]])
+    await expect(repo.update(ROW.id, {})).resolves.toEqual(EXPECTED_CARD)
+    expect(query).toHaveBeenCalledTimes(1)
+    expect(query.mock.calls[0][0]).toContain('SELECT')
+  })
+
+  it('update renvoie null si la carte est inconnue', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([{ affectedRows: 1 }]).mockResolvedValueOnce([[]])
+    await expect(repo.update('inconnu', { question: 'X' })).resolves.toBeNull()
+  })
+
+  it('delete renvoie true si une ligne est supprimée', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([{ affectedRows: 1 }])
+    await expect(repo.delete(ROW.id)).resolves.toBe(true)
+    expect(query.mock.calls[0][1]).toEqual([ROW.id])
+  })
+
+  it('delete renvoie false si aucune ligne ne correspond', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([{ affectedRows: 0 }])
+    await expect(repo.delete('inconnu')).resolves.toBe(false)
+  })
+
+  it('findRandom renvoie une carte au hasard ou null', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([[ROW]])
+    await expect(repo.findRandom()).resolves.toEqual(EXPECTED_CARD)
+    query.mockResolvedValueOnce([[]])
+    await expect(repo.findRandom()).resolves.toBeNull()
+  })
+
+  it('findRandomByTheme filtre par thème', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([[ROW]])
+    const card = await repo.findRandomByTheme('javascript')
+    expect(card).toEqual(EXPECTED_CARD)
+    const [sql, params] = query.mock.calls[0]
+    expect(sql).toContain('WHERE theme = ?')
+    expect(params).toEqual(['javascript'])
+  })
+
+  it('findThemes renvoie les thèmes distincts', async () => {
+    const { repo, query } = setup()
+    query.mockResolvedValueOnce([[{ theme: 'docker' }, { theme: 'javascript' }]])
+    await expect(repo.findThemes()).resolves.toEqual(['docker', 'javascript'])
+  })
+})
\ No newline at end of file
diff --git a/src/test/setup.ts b/src/test/setup.ts
index 6f13ed5..d2412e3 100644
--- a/src/test/setup.ts
+++ b/src/test/setup.ts
@@ -4,16 +4,18 @@ import { afterEach } from 'vitest'
 
 afterEach(() => cleanup())
 
-Object.defineProperty(window, 'matchMedia', {
-  writable: true,
-  value: (query: string) => ({
-    matches: false,
-    media: query,
-    onchange: null,
-    addListener: () => {},
-    removeListener: () => {},
-    addEventListener: () => {},
-    removeEventListener: () => {},
-    dispatchEvent: () => false,
-  }),
-})
+if (typeof window !== 'undefined') {
+  Object.defineProperty(window, 'matchMedia', {
+    writable: true,
+    value: (query: string) => ({
+      matches: false,
+      media: query,
+      onchange: null,
+      addListener: () => {},
+      removeListener: () => {},
+      addEventListener: () => {},
+      removeEventListener: () => {},
+      dispatchEvent: () => false,
+    }),
+  })
+}
\ No newline at end of file