Add cart.js coverage: redirect, no-redirect, fetch error, invalid price

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/js/cart.test.js

@@ -158,6 +158,80 @@ describe('initCart', () => {
         })
     })
 
+    it('redirects after successful checkout', async () => {
+        const fetchMock = vi.fn().mockResolvedValue({
+            json: () => Promise.resolve({ redirect: '/commande/1/paiement' }),
+        })
+        globalThis.fetch = fetchMock
+        globalThis.location = { href: '' }
+
+        createBilletterie([{ id: 1, price: '10.00', max: 5 }])
+        initCart()
+
+        document.querySelector('[data-cart-plus]').click()
+        document.getElementById('cart-checkout').click()
+
+        await new Promise(r => setTimeout(r, 10))
+
+        expect(globalThis.location.href).toBe('/commande/1/paiement')
+    })
+
+    it('does not redirect when response has no redirect', async () => {
+        const fetchMock = vi.fn().mockResolvedValue({
+            json: () => Promise.resolve({}),
+        })
+        globalThis.fetch = fetchMock
+        globalThis.location = { href: '/original' }
+
+        createBilletterie([{ id: 1, price: '10.00', max: 5 }])
+        initCart()
+
+        document.querySelector('[data-cart-plus]').click()
+        document.getElementById('cart-checkout').click()
+
+        await new Promise(r => setTimeout(r, 10))
+
+        expect(globalThis.location.href).toBe('/original')
+    })
+
+    it('re-enables button on fetch error', async () => {
+        const fetchMock = vi.fn().mockRejectedValue(new Error('Network error'))
+        globalThis.fetch = fetchMock
+
+        createBilletterie([{ id: 1, price: '10.00', max: 5 }])
+        initCart()
+
+        document.querySelector('[data-cart-plus]').click()
+        document.getElementById('cart-checkout').click()
+
+        await new Promise(r => setTimeout(r, 10))
+
+        const btn = document.getElementById('cart-checkout')
+        expect(btn.disabled).toBe(false)
+        expect(btn.textContent).toBe('Commander')
+    })
+
+    it('handles invalid price gracefully', () => {
+        document.body.innerHTML = `
+            <div id="billetterie">
+                <div data-cart-item data-billet-id="1" data-price="invalid" data-max="5">
+                    <button data-cart-minus></button>
+                    <input data-cart-qty type="number" min="0" max="5" value="0" readonly>
+                    <button data-cart-plus></button>
+                    <span data-cart-line-total></span>
+                </div>
+                <span id="cart-total"></span><span id="cart-count"></span>
+                <button id="cart-checkout" disabled data-order-url="/order"></button>
+            </div>
+        `
+        initCart()
+
+        document.querySelector('[data-cart-plus]').click()
+
+        expect(document.getElementById('cart-total').textContent).toBe('0,00 \u20AC')
+        expect(document.getElementById('cart-count').textContent).toBe('1')
+    })
+
     it('does not post when cart is empty on checkout', () => {
         const fetchMock = vi.fn()
         globalThis.fetch = fetchMock