test(02-04): add failing tests for companion text module

- Tests for getGreeting, getLetterIntro, getForestComment
- Covers API success, API failure, no config, rate-limited paths
- 12 test cases total with mocked dependencies

src/companion/companion.test.ts

@@ -0,0 +1,227 @@
+import "fake-indexeddb/auto";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { openDB } from "../storage/db";
+import type { GeminiConfig } from "../api/config";
+
+// Mock modules before importing the module under test
+vi.mock("../api/config", () => ({
+	loadConfig: vi.fn(),
+	resetConfigCache: vi.fn(),
+}));
+
+vi.mock("../api/gemini", () => ({
+	generateText: vi.fn(),
+	checkRateLimit: vi.fn(),
+	incrementApiCall: vi.fn(),
+}));
+
+import { loadConfig } from "../api/config";
+import {
+	checkRateLimit,
+	generateText,
+	incrementApiCall,
+} from "../api/gemini";
+import { getGreeting, getLetterIntro, getForestComment } from "./companion";
+
+const TEST_CONFIG: GeminiConfig = {
+	geminiApiKey: "test-key",
+	geminiModel: "gemini-2.5-flash",
+	imageModel: "gemini-3.1-flash-preview-image",
+};
+
+let testCounter = 0;
+let db: IDBDatabase;
+
+beforeEach(async () => {
+	vi.clearAllMocks();
+	testCounter++;
+	db = await openDB(`companion-test-${testCounter}`);
+});
+
+afterEach(() => {
+	vi.restoreAllMocks();
+});
+
+describe("getGreeting", () => {
+	it("returns AI text when API succeeds and rate limit not exceeded", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(TEST_CONFIG);
+		vi.mocked(checkRateLimit).mockResolvedValue(true);
+		vi.mocked(generateText).mockResolvedValue(
+			"Guten Morgen, kleiner Waldfreund!",
+		);
+
+		const result = await getGreeting("fee", db);
+
+		expect(result).toBe("Guten Morgen, kleiner Waldfreund!");
+		expect(generateText).toHaveBeenCalledTimes(1);
+		expect(incrementApiCall).toHaveBeenCalledWith(db, "text");
+	});
+
+	it("returns fallback text when loadConfig returns null (no API key)", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(null);
+
+		const result = await getGreeting("fee", db);
+
+		expect(result).toBeTruthy();
+		expect(typeof result).toBe("string");
+		expect(generateText).not.toHaveBeenCalled();
+	});
+
+	it("returns fallback text when generateText returns null (API error)", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(TEST_CONFIG);
+		vi.mocked(checkRateLimit).mockResolvedValue(true);
+		vi.mocked(generateText).mockResolvedValue(null);
+
+		const result = await getGreeting("fee", db);
+
+		expect(result).toBeTruthy();
+		expect(typeof result).toBe("string");
+		expect(incrementApiCall).not.toHaveBeenCalled();
+	});
+
+	it("returns fallback text when rate limit exceeded", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(TEST_CONFIG);
+		vi.mocked(checkRateLimit).mockResolvedValue(false);
+
+		const result = await getGreeting("fee", db);
+
+		expect(result).toBeTruthy();
+		expect(generateText).not.toHaveBeenCalled();
+	});
+
+	it("passes correct system prompt with companion personality and time of day", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(TEST_CONFIG);
+		vi.mocked(checkRateLimit).mockResolvedValue(true);
+		vi.mocked(generateText).mockResolvedValue("Hallo!");
+
+		await getGreeting("fee", db);
+
+		const systemPrompt = vi.mocked(generateText).mock.calls[0]![1];
+		expect(systemPrompt).toContain("Lila");
+		expect(systemPrompt).toContain(
+			"Sanft, ermutigend, ein bisschen vertraeumt",
+		);
+		expect(systemPrompt).toMatch(/morgen|mittag|abend/);
+		expect(systemPrompt).toContain("Max. 2 kurze Saetze");
+	});
+
+	it("calls incrementApiCall after successful API call", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(TEST_CONFIG);
+		vi.mocked(checkRateLimit).mockResolvedValue(true);
+		vi.mocked(generateText).mockResolvedValue("Hallo Waldkind!");
+
+		await getGreeting("einhorn", db);
+
+		expect(incrementApiCall).toHaveBeenCalledWith(db, "text");
+	});
+});
+
+describe("getLetterIntro", () => {
+	it("returns AI text when API succeeds", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(TEST_CONFIG);
+		vi.mocked(checkRateLimit).mockResolvedValue(true);
+		vi.mocked(generateText).mockResolvedValue(
+			"Das F ist wie ein Farn im Wald!",
+		);
+
+		const result = await getLetterIntro(
+			"fee",
+			"f",
+			"linker Zeigefinger",
+			db,
+		);
+
+		expect(result).toBe("Das F ist wie ein Farn im Wald!");
+		expect(incrementApiCall).toHaveBeenCalledWith(db, "text");
+	});
+
+	it("returns fallback LetterIntro text when API unavailable", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(null);
+
+		const result = await getLetterIntro(
+			"fee",
+			"f",
+			"linker Zeigefinger",
+			db,
+		);
+
+		expect(result).toBeTruthy();
+		expect(result).toContain("Zeigefinger");
+		expect(generateText).not.toHaveBeenCalled();
+	});
+
+	it("system prompt includes letter, finger description, and companion personality", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(TEST_CONFIG);
+		vi.mocked(checkRateLimit).mockResolvedValue(true);
+		vi.mocked(generateText).mockResolvedValue("Das D wohnt hier!");
+
+		await getLetterIntro("fuchs", "d", "linker Mittelfinger", db);
+
+		const systemPrompt = vi.mocked(generateText).mock.calls[0]![1];
+		expect(systemPrompt).toContain("Finn");
+		expect(systemPrompt).toContain("Ruhig, weise, humorvoll");
+		expect(systemPrompt).toContain("d");
+		expect(systemPrompt).toContain("linker Mittelfinger");
+	});
+
+	it("returns default text when fallback not found for unknown letter", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(null);
+
+		const result = await getLetterIntro(
+			"fee",
+			"z",
+			"linker kleiner Finger",
+			db,
+		);
+
+		expect(result).toBe("Druecke die leuchtende Taste!");
+	});
+});
+
+describe("getForestComment", () => {
+	it("returns AI text when API succeeds", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(TEST_CONFIG);
+		vi.mocked(checkRateLimit).mockResolvedValue(true);
+		vi.mocked(generateText).mockResolvedValue(
+			"Oh, ein Schmetterling ist erschienen!",
+		);
+
+		const result = await getForestComment(
+			"eule",
+			"ein blauer Schmetterling",
+			db,
+		);
+
+		expect(result).toBe("Oh, ein Schmetterling ist erschienen!");
+		expect(incrementApiCall).toHaveBeenCalledWith(db, "text");
+	});
+
+	it("returns fallback text when API unavailable", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(null);
+
+		const result = await getForestComment(
+			"eule",
+			"ein blauer Schmetterling",
+			db,
+		);
+
+		expect(result).toBeTruthy();
+		expect(typeof result).toBe("string");
+		expect(generateText).not.toHaveBeenCalled();
+	});
+
+	it("system prompt includes element description and companion personality", async () => {
+		vi.mocked(loadConfig).mockResolvedValue(TEST_CONFIG);
+		vi.mocked(checkRateLimit).mockResolvedValue(true);
+		vi.mocked(generateText).mockResolvedValue("Wie wunderschoen!");
+
+		await getForestComment("einhorn", "ein leuchtender Pilz", db);
+
+		const systemPrompt = vi.mocked(generateText).mock.calls[0]![1];
+		expect(systemPrompt).toContain("Stella");
+		expect(systemPrompt).toContain(
+			"Froehlich, enthusiastisch, feiert jeden kleinen Erfolg",
+		);
+		expect(systemPrompt).toContain("ein leuchtender Pilz");
+	});
+});