1 files changed, 212 insertions, 0 deletions
diff --git a/src/server/repositories/deck.test.ts b/src/server/repositories/deck.test.ts
new file mode 100644
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+++ b/src/server/repositories/deck.test.ts
@@ -0,0 +1,212 @@
+import { describe, expect, it, vi } from "vitest";
+import type { Deck, DeckRepository } from "./types.js";
+
+function createMockDeck(overrides: Partial<Deck> = {}): Deck {
+	return {
+		id: "deck-uuid-123",
+		userId: "user-uuid-123",
+		name: "Test Deck",
+		description: null,
+		newCardsPerDay: 20,
+		createdAt: new Date("2024-01-01"),
+		updatedAt: new Date("2024-01-01"),
+		deletedAt: null,
+		syncVersion: 0,
+		...overrides,
+	};
+}
+
+function createMockDeckRepo(): DeckRepository {
+	return {
+		findByUserId: vi.fn(),
+		findById: vi.fn(),
+		create: vi.fn(),
+		update: vi.fn(),
+		softDelete: vi.fn(),
+	};
+}
+
+describe("DeckRepository mock factory", () => {
+	describe("createMockDeck", () => {
+		it("creates a valid Deck with defaults", () => {
+			const deck = createMockDeck();
+
+			expect(deck.id).toBe("deck-uuid-123");
+			expect(deck.userId).toBe("user-uuid-123");
+			expect(deck.name).toBe("Test Deck");
+			expect(deck.description).toBeNull();
+			expect(deck.newCardsPerDay).toBe(20);
+			expect(deck.deletedAt).toBeNull();
+			expect(deck.syncVersion).toBe(0);
+		});
+
+		it("allows overriding properties", () => {
+			const deck = createMockDeck({
+				id: "custom-id",
+				name: "Custom Deck",
+				description: "A description",
+				newCardsPerDay: 50,
+			});
+
+			expect(deck.id).toBe("custom-id");
+			expect(deck.name).toBe("Custom Deck");
+			expect(deck.description).toBe("A description");
+			expect(deck.newCardsPerDay).toBe(50);
+		});
+	});
+
+	describe("createMockDeckRepo", () => {
+		it("creates a repository with all required methods", () => {
+			const repo = createMockDeckRepo();
+
+			expect(repo.findByUserId).toBeDefined();
+			expect(repo.findById).toBeDefined();
+			expect(repo.create).toBeDefined();
+			expect(repo.update).toBeDefined();
+			expect(repo.softDelete).toBeDefined();
+		});
+
+		it("methods are mockable for findByUserId", async () => {
+			const repo = createMockDeckRepo();
+			const mockDecks = [
+				createMockDeck({ id: "deck-1" }),
+				createMockDeck({ id: "deck-2" }),
+			];
+
+			vi.mocked(repo.findByUserId).mockResolvedValue(mockDecks);
+
+			const results = await repo.findByUserId("user-123");
+			expect(results).toHaveLength(2);
+			expect(repo.findByUserId).toHaveBeenCalledWith("user-123");
+		});
+
+		it("methods are mockable for findById", async () => {
+			const repo = createMockDeckRepo();
+			const mockDeck = createMockDeck();
+
+			vi.mocked(repo.findById).mockResolvedValue(mockDeck);
+
+			const found = await repo.findById("deck-id", "user-id");
+			expect(found).toEqual(mockDeck);
+			expect(repo.findById).toHaveBeenCalledWith("deck-id", "user-id");
+		});
+
+		it("returns undefined when deck not found", async () => {
+			const repo = createMockDeckRepo();
+
+			vi.mocked(repo.findById).mockResolvedValue(undefined);
+
+			expect(await repo.findById("nonexistent", "user-id")).toBeUndefined();
+		});
+
+		it("returns false when soft delete fails", async () => {
+			const repo = createMockDeckRepo();
+
+			vi.mocked(repo.softDelete).mockResolvedValue(false);
+
+			expect(await repo.softDelete("nonexistent", "user-id")).toBe(false);
+		});
+	});
+});
+
+describe("Deck interface contracts", () => {
+	it("Deck has required sync fields", () => {
+		const deck = createMockDeck();
+
+		expect(deck).toHaveProperty("syncVersion");
+		expect(deck).toHaveProperty("createdAt");
+		expect(deck).toHaveProperty("updatedAt");
+		expect(deck).toHaveProperty("deletedAt");
+	});
+
+	it("Deck has required user association", () => {
+		const deck = createMockDeck();
+
+		expect(deck).toHaveProperty("userId");
+	});
+
+	it("Deck has required configuration fields", () => {
+		const deck = createMockDeck();
+
+		expect(deck).toHaveProperty("name");
+		expect(deck).toHaveProperty("description");
+		expect(deck).toHaveProperty("newCardsPerDay");
+	});
+});
+
+describe("findByUserId ordering", () => {
+	it("returns decks ordered by createdAt", async () => {
+		const repo = createMockDeckRepo();
+
+		// Simulate decks created at different times
+		const oldDeck = createMockDeck({
+			id: "deck-old",
+			name: "Old Deck",
+			createdAt: new Date("2024-01-01"),
+		});
+		const newDeck = createMockDeck({
+			id: "deck-new",
+			name: "New Deck",
+			createdAt: new Date("2024-06-01"),
+		});
+
+		// Mock returns decks in createdAt order (oldest first)
+		vi.mocked(repo.findByUserId).mockResolvedValue([oldDeck, newDeck]);
+
+		const results = await repo.findByUserId("user-123");
+
+		expect(results).toHaveLength(2);
+		expect(results[0]?.id).toBe("deck-old");
+		expect(results[1]?.id).toBe("deck-new");
+		// Verify the order is by createdAt
+		expect(results[0]?.createdAt.getTime()).toBeLessThan(
+			results[1]?.createdAt.getTime() ?? 0,
+		);
+	});
+
+	it("returns empty array when user has no decks", async () => {
+		const repo = createMockDeckRepo();
+
+		vi.mocked(repo.findByUserId).mockResolvedValue([]);
+
+		const results = await repo.findByUserId("user-with-no-decks");
+		expect(results).toHaveLength(0);
+	});
+
+	it("returns single deck when user has one deck", async () => {
+		const repo = createMockDeckRepo();
+		const singleDeck = createMockDeck({ id: "only-deck" });
+
+		vi.mocked(repo.findByUserId).mockResolvedValue([singleDeck]);
+
+		const results = await repo.findByUserId("user-123");
+		expect(results).toHaveLength(1);
+		expect(results[0]?.id).toBe("only-deck");
+	});
+
+	it("maintains consistent ordering across multiple calls", async () => {
+		const repo = createMockDeckRepo();
+
+		const deck1 = createMockDeck({
+			id: "deck-1",
+			createdAt: new Date("2024-01-01"),
+		});
+		const deck2 = createMockDeck({
+			id: "deck-2",
+			createdAt: new Date("2024-02-01"),
+		});
+		const deck3 = createMockDeck({
+			id: "deck-3",
+			createdAt: new Date("2024-03-01"),
+		});
+
+		vi.mocked(repo.findByUserId).mockResolvedValue([deck1, deck2, deck3]);
+
+		const results1 = await repo.findByUserId("user-123");
+		const results2 = await repo.findByUserId("user-123");
+
+		// Order should be consistent
+		expect(results1.map((d) => d.id)).toEqual(results2.map((d) => d.id));
+		expect(results1.map((d) => d.id)).toEqual(["deck-1", "deck-2", "deck-3"]);
+	});
+});