test(web): cover the difficulty-hint table and the last-difficulty setting

difficultyHints is walked against the Difficulty schema the same way
difficultyLabels already is, and the settings store gets coverage for
lastDifficulty: starts unset, persists across a reload, ignores a corrupt
stored value, and stays usable in memory when storage is hostile.

web/tests/i18n.test.js

@@ -14,6 +14,7 @@ import {
 	PointKindSchema
 } from '../src/lib/proto/noitu/v1/game_pb.js';
 import {
+	difficultyHints,
 	difficultyLabels,
 	endReasonMessages,
 	errorFallback,
@@ -105,6 +106,14 @@ describe('difficulty labels', () => {
 			expect(difficultyLabels[value], `Difficulty ${value} has no label`).toBeTypeOf('string');
 		}
 	});
+
+	it('gives every playable difficulty a hint for the record line to fall back on', () => {
+		const playable = valuesOf(DifficultySchema).filter((v) => v !== Difficulty.UNSPECIFIED);
+		for (const value of playable) {
+			expect(difficultyHints[value], `Difficulty ${value} has no hint`).toBeTypeOf('string');
+			expect(difficultyHints[value].length).toBeGreaterThan(0);
+		}
+	});
 });
 
 describe('server error codes', () => {

web/tests/settings-store.test.js

@@ -138,6 +138,26 @@ describe('best scores', () => {
 	});
 });
 
+describe('last difficulty', () => {
+	it('starts with none picked, so a caller falls back to its own default', () => {
+		const store = createSettingsStore();
+		expect(store.state.lastDifficulty).toBeNull();
+	});
+
+	it('remembers the rung last picked', () => {
+		const store = createSettingsStore();
+		store.setLastDifficulty(Difficulty.HARD);
+
+		expect(store.state.lastDifficulty).toBe(Difficulty.HARD);
+		expect(createSettingsStore().state.lastDifficulty).toBe(Difficulty.HARD);
+	});
+
+	it('ignores a stored value that is not a number', () => {
+		localStorage.setItem('noitu.lastDifficulty', 'not-a-number');
+		expect(createSettingsStore().state.lastDifficulty).toBeNull();
+	});
+});
+
 describe('when storage is unavailable', () => {
 	it('constructs with working defaults instead of throwing', () => {
 		useStorage(hostileStorage());
@@ -145,6 +165,7 @@ describe('when storage is unavailable', () => {
 
 		expect(store.state.nickname).toBe('');
 		expect(store.state.bestScores).toEqual({});
+		expect(store.state.lastDifficulty).toBeNull();
 		expect(['light', 'dark']).toContain(store.state.theme);
 	});
 
@@ -155,10 +176,12 @@ describe('when storage is unavailable', () => {
 		expect(() => store.setNickname('Minh')).not.toThrow();
 		expect(() => store.setTheme('dark')).not.toThrow();
 		expect(store.recordScore(Difficulty.HARD, 7)).toBe(true);
+		expect(() => store.setLastDifficulty(Difficulty.EASY)).not.toThrow();
 
 		expect(store.state.nickname).toBe('Minh');
 		expect(store.state.theme).toBe('dark');
 		expect(store.bestScore(Difficulty.HARD)).toBe(7);
+		expect(store.state.lastDifficulty).toBe(Difficulty.EASY);
 	});
 
 	it('survives a browser that throws on the property itself', () => {