Add backend unit/integration tests, Playwright e2e tests, README, cookie Secure fix

backend/tests/unit/utils.test.ts

@@ -0,0 +1,47 @@
+import { toCents, formatPrice, isValidEmail } from '../../src/utils';
+
+describe('toCents', () => {
+  it('converts a dollar string to integer cents', () => {
+    expect(toCents('19.99')).toBe(1999);
+  });
+
+  it('converts a plain number to integer cents', () => {
+    expect(toCents(5)).toBe(500);
+  });
+
+  it('rounds to the nearest cent', () => {
+    expect(toCents('19.999')).toBe(2000);
+  });
+
+  it('throws on non-numeric input', () => {
+    expect(() => toCents('not-a-number')).toThrow('invalid price');
+  });
+
+  it('throws on a negative price', () => {
+    expect(() => toCents(-5)).toThrow('invalid price');
+  });
+});
+
+describe('formatPrice', () => {
+  it('formats cents as a dollar string', () => {
+    expect(formatPrice(1999)).toBe('$19.99');
+  });
+
+  it('pads to two decimal places', () => {
+    expect(formatPrice(500)).toBe('$5.00');
+  });
+});
+
+describe('isValidEmail', () => {
+  it('accepts a well-formed email', () => {
+    expect(isValidEmail('thom@example.com')).toBe(true);
+  });
+
+  it('rejects a string with no @', () => {
+    expect(isValidEmail('not-an-email')).toBe(false);
+  });
+
+  it('rejects an email with no domain', () => {
+    expect(isValidEmail('thom@')).toBe(false);
+  });
+});