🚨 Add tests for workbook helper (#2020)

Author: KATO-Hiro

src/test/lib/utils/workbooks.test.ts

@@ -1,7 +1,25 @@
 import { expect, test } from 'vitest';
 
-import { canViewWorkBook } from '$lib/utils/workbooks';
+import { canViewWorkBook, getUrlSlugFrom } from '$lib/utils/workbooks';
 import { Roles } from '$lib/types/user';
+import { type WorkbookList, WorkBookType } from '$lib/types/workbook';
+
+function createWorkBookListBase(overrides: Partial<WorkbookList> = {}): WorkbookList {
+  return {
+    id: 1,
+    authorId: '3',
+    authorName: 'Alice',
+    title: '実装力を鍛える問題集',
+    description: '',
+    editorialUrl: '',
+    isPublished: false,
+    isOfficial: false,
+    isReplenished: false,
+    workBookType: WorkBookType.CREATED_BY_USER,
+    workBookTasks: [],
+    ...overrides,
+  };
+}
 
 describe('Workbooks', () => {
   describe('can view workbooks', () => {
@@ -25,4 +43,26 @@ describe('Workbooks', () => {
       });
     });
   });
+
+  describe('get url slug from workbook', () => {
+    test('returns urlSlug when it exists', () => {
+      const workbook = createWorkBookListBase({ id: 1, urlSlug: '2-sat' });
+      expect(getUrlSlugFrom(workbook)).toBe('2-sat');
+    });
+
+    test('returns id as string when urlSlug is null', () => {
+      const workbook = createWorkBookListBase({ id: 10, urlSlug: null });
+      expect(getUrlSlugFrom(workbook)).toBe('10');
+    });
+
+    test('returns id as string when urlSlug is undefined', () => {
+      const workbook = createWorkBookListBase({ id: 123, urlSlug: undefined });
+      expect(getUrlSlugFrom(workbook)).toBe('123');
+    });
+
+    test('returns id as string when urlSlug is empty string', () => {
+      const workbook = createWorkBookListBase({ id: 999, urlSlug: '' });
+      expect(getUrlSlugFrom(workbook)).toBe('999');
+    });
+  });
 });