not getting the same precise error message, but perhaps the intent is the same?; anyway, updated views & some FTs, base.html for more dynamic error handling (tho incomplete)

src/apps/dashboard/tests/test_models.py

@@ -1,3 +1,5 @@
+from django.core.exceptions import ValidationError
+from django.db.utils import IntegrityError
 from django.test import TestCase
 from ..models import Item, List
 
@@ -28,4 +30,15 @@ class ListAndItemModelsTest(TestCase):
         self.assertEqual(first_saved_item.list, mylist)
         self.assertEqual(second_saved_item.text, "A sequel somehow better than the first")
         self.assertEqual(second_saved_item.list, mylist)
-        
+
+    def test_cannot_save_null_list_items(self):
+        mylist = List.objects.create()
+        item = Item(list=mylist, text=None)
+        with self.assertRaises(IntegrityError):
+            item.save()
+
+    def test_cannot_save_empty_list_items(self):
+        mylist = List.objects.create()
+        item = Item(list=mylist, text="")
+        with self.assertRaises(ValidationError):
+            item.full_clean()

src/apps/dashboard/tests/test_views.py

@@ -1,4 +1,5 @@
 from django.test import TestCase
+from django.utils import html
 from ..models import Item, List
 import lxml.html
 
@@ -56,6 +57,18 @@ class NewListTest(TestCase):
         new_list = List.objects.get()
         self.assertRedirects(response, f'/apps/dashboard/{new_list.id}/')
 
+    def test_validation_errors_are_sent_back_to_home_page_template(self):
+        response = self.client.post("/apps/dashboard/newlist", data={"item_text": ""})
+        self.assertEqual(response.status_code, 200)
+        self.assertTemplateUsed(response, "apps/dashboard/home.html")
+        expected_error = html.escape("You can't have an empty list item")
+        self.assertContains(response, expected_error)
+        
+    def test_invalid_list_items_never_save(self):
+        self.client.post("/apps/dashboard/newlist", data={"item_text": ""})
+        self.assertEqual(List.objects.count(), 0)
+        self.assertEqual(Item.objects.count(), 0)
+
 class NewItemTest(TestCase):
     def test_can_save_a_POST_request_to_an_existing_list(self):
         other_list = List.objects.create()

src/apps/dashboard/views.py

@@ -1,18 +1,26 @@
+from django.core.exceptions import ValidationError
 from django.shortcuts import redirect, render
 from .models import Item, List
 
 def home_page(request):
     return render(request, 'apps/dashboard/home.html')
 
+def new_list(request):
+    nulist = List.objects.create()
+    item = Item(text=request.POST['item_text'], list=nulist)
+    try:
+        item.full_clean()
+        item.save()
+    except ValidationError:
+        nulist.delete()
+        error = "You can't have an empty list item"
+        return render(request, "apps/dashboard/home.html", {"error": error})
+    return redirect(f'/apps/dashboard/{nulist.id}/')
+
 def view_list(request, list_id):
     our_list = List.objects.get(id=list_id)
     return render(request, 'apps/dashboard/list.html', {'list': our_list})
 
-def new_list(request):
-    nulist = List.objects.create()
-    Item.objects.create(text=request.POST['item_text'], list=nulist)
-    return redirect(f'/apps/dashboard/{nulist.id}/')
-
 def add_item(request, list_id):
     our_list = List.objects.get(id=list_id)
     Item.objects.create(text=request.POST['item_text'], list=our_list)