fix: handle inventory validation errors on checkout

src/screens/CheckoutScreen.tsx

@@ -98,12 +98,27 @@ const CheckoutScreen = () => {
       throw new Error(err);
     });
     setOrderStatusUI(false);
+
     if (response.status !== 200) {
+      let errorMessage = 'Error: Could not place order.';
+
+      if (response.status === 422) {
+        try {
+          const errorData = await response.json();
+          if (errorData.error === 'inventory_validation_failed') {
+            errorMessage = `Inventory issue: ${errorData.message}`;
+          }
+        } catch (e) {
+          // If parsing fails, use the generic error message
+          console.error('Failed to parse error response:', e);
+        }
+      }
+
       uiToast
         ? uiToast.show({
             type: 'error',
             position: 'bottom',
-            text1: 'Error: Could not place order.',
+            text1: errorMessage,
           })
         : null;
 

tests/test_checkout.py

@@ -0,0 +1,90 @@
+import pytest
+import json
+from app import app, db
+from models import Product
+
+@pytest.fixture
+def client():
+    app.config['TESTING'] = True
+    with app.test_client() as client:
+        with app.app_context():
+            db.create_all()
+            # Setup test data
+            product1 = Product(id=1, name="Test Plant 1", price=19.99, inventory=5)
+            product2 = Product(id=2, name="Test Plant 2", price=29.99, inventory=2)
+            db.session.add(product1)
+            db.session.add(product2)
+            db.session.commit()
+            yield client
+            db.session.remove()
+            db.drop_all()
+
+def test_checkout_inventory_validation(client):
+    """Test that checkout returns proper error when inventory is insufficient"""
+    # Create a cart with more items than available in inventory
+    cart_data = {
+        "cart": {
+            "items": [
+                {"id": 1, "name": "Test Plant 1", "price": 19.99, "quantity": 1},
+                {"id": 2, "name": "Test Plant 2", "price": 29.99, "quantity": 5}  # Only 2 in stock
+            ],
+            "quantities": {"1": 1, "2": 5}
+        },
+        "form": {
+            "email": "[email protected]",
+            "firstName": "Test",
+            "lastName": "User"
+        }
+    }
+
+    response = client.post(
+        '/checkout',
+        data=json.dumps(cart_data),
+        content_type='application/json'
+    )
+
+    # Assert that we get a 422 Unprocessable Entity status code
+    assert response.status_code == 422
+
+    # Assert that the response contains the expected error details
+    data = json.loads(response.data)
+    assert data['error'] == 'inventory_validation_failed'
+    assert 'Not enough inventory' in data['message']
+    assert len(data['details']) == 1
+    assert data['details'][0]['id'] == 2
+    assert data['details'][0]['requested'] == 5
+    assert data['details'][0]['available'] == 2
+
+def test_checkout_successful(client):
+    """Test that checkout works when inventory is sufficient"""
+    # Create a cart with items within inventory limits
+    cart_data = {
+        "cart": {
+            "items": [
+                {"id": 1, "name": "Test Plant 1", "price": 19.99, "quantity": 2},
+                {"id": 2, "name": "Test Plant 2", "price": 29.99, "quantity": 1}
+            ],
+            "quantities": {"1": 2, "2": 1}
+        },
+        "form": {
+            "email": "[email protected]",
+            "firstName": "Test",
+            "lastName": "User"
+        }
+    }
+
+    response = client.post(
+        '/checkout',
+        data=json.dumps(cart_data),
+        content_type='application/json'
+    )
+
+    # Assert that we get a 200 OK status code
+    assert response.status_code == 200
+
+    # Verify that inventory was updated
+    with app.app_context():
+        product1 = Product.query.get(1)
+        product2 = Product.query.get(2)
+        assert product1.inventory == 3  # Started with 5, used 2
+        assert product2.inventory == 1  # Started with 2, used 1