feat: frontend unit tests

frontend/tests/utils/helpers/csrfToken.test.ts

@@ -0,0 +1,56 @@
+import { csrfToken } from '../../../src/static/js/utils/helpers/csrfToken';
+
+const setupDocumentCookie = () => {
+    if (typeof document === 'undefined') {
+        globalThis.document = { cookie: '' } as unknown as Document;
+    }
+};
+
+const setDocumentCookie = (value: string) => {
+    if (typeof document !== 'undefined') {
+        Object.defineProperty(document, 'cookie', { value, writable: true, configurable: true });
+    }
+};
+
+describe('js/utils/helpers', () => {
+    describe('csrfToken', () => {
+        const originalCookie = document.cookie;
+
+        beforeAll(() => {
+            // Initialize document environment
+            setupDocumentCookie();
+        });
+
+        afterEach(() => {
+            // Restore original cookie string
+            setDocumentCookie(originalCookie);
+        });
+
+        test('Returns null when document.cookie is empty', () => {
+            setDocumentCookie('');
+            expect(csrfToken()).toBeNull();
+        });
+
+        test('Returns null when csrftoken is not present', () => {
+            setDocumentCookie('sessionid=abc; theme=dark');
+            expect(csrfToken()).toBeNull();
+        });
+
+        test('Finds and decodes the csrftoken cookie value', () => {
+            const token = encodeURIComponent('a b+c%20');
+            setDocumentCookie(`sessionid=abc; csrftoken=${token}; theme=dark`);
+            expect(csrfToken()).toBe('a b+c%20');
+        });
+
+        test('Ignores leading spaces and matches exact prefix csrftoken=', () => {
+            setDocumentCookie('  sessionid=xyz;   csrftoken=secure123; other=value');
+            expect(csrfToken()).toBe('secure123');
+        });
+
+        test('Stops scanning once csrftoken is found', () => {
+            // Ensure csrftoken occurs before other long tail cookies
+            setDocumentCookie('csrftoken=first; a=1; b=2; c=3; d=4; e=5');
+            expect(csrfToken()).toBe('first');
+        });
+    });
+});